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The variability in the response to antipsychotic medication in schizophrenia may reflect between-patient differences in neurobiology. Recent cross-sectional neuroimaging studies suggest that a poorer therapeutic response is associated with relatively normal striatal dopamine synthesis capacity but elevated anterior cingulate cortex (ACC) glutamate levels. We sought to test whether these measures can differentiate patients with psychosis who are antipsychotic responsive from those who are antipsychotic nonresponsive in a multicenter cross-sectional study. 1H-magnetic resonance spectroscopy (1H-MRS) was used to measure glutamate levels (Glucorr) in the ACC and in the right striatum in 92 patients across 4 sites (48 responders [R] and 44 nonresponders [NR]). In 54 patients at 2 sites (25 R and 29 NR), we additionally acquired 3,4-dihydroxy-6-[18F]fluoro-l-phenylalanine (18F-DOPA) positron emission tomography (PET) to index striatal dopamine function (Kicer, min−1). The mean ACC Glucorr was higher in the NR than the R group after adjustment for age and sex (F1,80 = 4.27; P = .04). This was associated with an area under the curve for the group discrimination of 0.59. There were no group differences in striatal dopamine function or striatal Glucorr. The results provide partial further support for a role of ACC glutamate, but not striatal dopamine synthesis, in determining the nature of the response to antipsychotic medication. The low discriminative accuracy might be improved in groups with greater clinical separation or increased in future studies that focus on the antipsychotic response at an earlier stage of the disorder and integrate other candidate predictive biomarkers. Greater harmonization of multicenter PET and 1H-MRS may also improve sensitivity.

Background Response to antidepressants in major depressive disorder is variable and determinants are not well understood or used to design clinical trials. We aimed to understand these determinants. Methods Supported by Innovative Medicines Initiative, as part of a large public-private collaboration (NEWMEDS), we assembled the largest dataset of individual patient level information from industry sponsored randomized placebo-controlled trials of antidepressant drugs in adults with MDD. We examined patient and trial-design-related determinants of outcome as measured by change on Hamilton Depression Scale or Montgomery–Asberg Depression Rating Scale in 34 placebo-controlled trials (drug, n = 8260; placebo, n = 3957). Results While it is conventional for trials to be 6–8 weeks long, drug-placebo differences were nearly the same at week 4 as at week 6 and with lower dropout rates. At the multivariate level, having any of these attributes was significantly associated with greater drug vs. placebo differences on symptom improvement: female, increasing proportion of patients on placebo, centers located outside of North America, centers with low placebo response (regardless of active treatment response) and using randomized withdrawal designs. Limitations Data on compounds that failed were not available to us. Findings may not be relevant for new mechanisms of action. Conclusions Proof of concept trials can be shorter and efficiency improved by selecting enriched populations based on clinical and demographic variables, ensuring adequate balance of placebo patients, and carefully selecting and monitoring centers. In addition to improving drug discovery, patient exposure to placebo and experimental treatments can be reduced.

Introduction: There is an ongoing debate about whether negative affect are consequences or triggers of paranoid thinking. It has also been suggested that aberrant salience is central to the development of delusions. This study modelled the moment-to-moment relationships between negative affect, aberrant salience, and paranoia in acute inpatients with psychosis.Methods: Participants with active paranoid delusions were assessed using clinical rating scales and experience sampling method (ESM) over 14 days. ESM data were analysed using time-lagged multilevel regression modelling.Results: Both negative affect and aberrant salience predicted an increase in paranoia at the next time point. Conversely, the level of paranoia did not predict subsequent changes in negative affect or aberrant salience. Negative affect predicted an increase in aberrant salience at the next time point, and vice versa.Conclusions: Negative affect and aberrant salience appear to drive and exacerbate paranoia, rather than being merely the sequelae of the symptom. Our results suggest both direct and indirect (via aberrant salience) pathways from negative affect to paranoia.

Adenosine A

Huntington's disease (HD) is a monogenic neurodegenerative disorder with an underlying pathology involving the toxic effect of mutant huntingtin protein primarily in striatal and cortical neurons. Phosphodiesterase 10A (PDE10A) regulates intracellular signalling cascades, thus having a key role in promoting neuronal survival. Using positron emission tomography (PET) with [(11)C]IMA107, we investigated the in vivo extra-striatal expression of PDE10A in 12 early premanifest HD gene carriers. Image processing and kinetic modelling was performed using MIAKAT™. Parametric images of [(11)C]IMA107 non-displaceable binding potential (BPND) were generated from the dynamic [(11)C]IMA107 scans using the simplified reference tissue model with the cerebellum as the reference tissue for nonspecific binding. We set a threshold criterion for meaningful quantification of [(11)C]IMA107 BPND at 0.30 in healthy control data; regions meeting this criterion were designated as regions of interest (ROIs). MRI-based volumetric analysis showed no atrophy in ROIs. We found significant differences in mean ROIs [(11)C]IMA107 BPND between HD gene carriers and healthy controls. HD gene carriers had significant loss of PDE10A within the insular cortex and occipital fusiform gyrus compared to healthy controls. Insula and occipital fusiform gyrus are important brain areas for the regulation of cognitive and limbic function that is impaired in HD. Our findings suggest that dysregulation of PDE10A-mediated intracellular signalling could be an early phenomenon in the course of HD with relevance also for extra-striatal brain areas.

Proton magnetic resonance spectroscopy ((1)H MRS) studies in schizophrenia patients generally report decreased levels of N-acetyl-aspartate (NAA), glutamate and glutathione, particularly in frontal cortex. However, these data are inconsistent in part due to confounds associated with clinical samples. The lack of validated diagnostic biomarkers also hampers analysis of the neurodevelopmental trajectory of neurochemical abnormalities. Rodent models are powerful tools to address these issues, particularly when combined with (1)H MRS (clinically comparable technology). We investigated the trajectory of metabolic changes in the prefrontal cortex during brain maturation from adolescence to adulthood in vivo using (1)H MRS in rats exposed prenatally to polyinosinic-polycytidylic acid (POL), a rodent model of maternal immune activation (MIA), an epidemiological risk factor for several psychiatric disorders with a neurodevelopmental origin. Longitudinal in vivo (1)H MRS revealed a significant decrease in PFC levels of GSH and taurine in adult, but not adolescent rats. Significant age×MIA interactions for PFC levels of NAA were also observed. These data replicate some deficits observed in the PFC of patients with schizophrenia. There were no significant changes in the levels of glutamate or any other metabolite. These data suggest prenatal exposure to POL leads to subtle metabolic perturbations of the normal maturing PFC, which may be related to subsequent behavioural abnormalities. Further work is however required to examine any potential confound of shipping stress on the presumed imbalances in PFC metabolites in POL-exposed offspring. Testing the interactions between MIA with stress or genetic risk variants will also be an important advance.

Neuroinflammation is increasingly implicated in the pathogenesis of Schizophrenia (SCZ). In addition, there is increasing evidence for a relationship between the dose and duration of antipsychotic drug (APD) treatment and reductions in grey matter volume. The potential contribution of microglia to these phenomena is however not yet defined. Adult rats were treated with a common vehicle, haloperidol (HAL, 2 mg/kg/day) or olanzapine (OLZ, 10 mg/kg/day) for 8 weeks via an osmotic mini-pump implanted subcutaneously. Microglial cells, identified by their Iba-1 immunoreactivity, were quantified in four regions of interest chosen based on previous neuroimaging data: the hippocampus, anterior cingulate cortex, corpus striatum, and secondary somatosensory cortex. Those cells were also analysed according to their morphology, providing an index of their activation state. Chronic APD treatment resulted in increased density of total microglia in the hippocampus, striatum, and somatosensory cortex, but not in the ACC. Importantly, in all brain regions studied, both APD tested led to a dramatic shift towards an amoeboid, reactive, microglial morphology after chronic treatment compared to vehicle-treated controls. These data provide the first in vivo evidence that chronic APD treatment at clinically relevant doses leads to microglial proliferation and morphological changes indicative of activated microglia in the naïve rat brain. Although caution needs to be exerted when extrapolating results from animals to patients, these data suggest a potential contribution of antipsychotic medication to markers of brain inflammation. Further investigation of the links between antipsychotic treatment and the immune system are warranted.

There is an urgent need for early biomarkers and novel disease-modifying therapies in Huntington's disease. Huntington's disease pathology involves the toxic effect of mutant huntingtin primarily in striatal medium spiny neurons, which highly express phosphodiesterase 10A (PDE10A). PDE10A hydrolyses cAMP/cGMP signalling cascades, thus having a key role in the regulation of striatal output, and in promoting neuronal survival. PDE10A could be a key therapeutic target in Huntington's disease. Here, we used combined positron emission tomography (PET) and multimodal magnetic resonance imaging to assess PDE10A expression in vivo in a unique cohort of 12 early premanifest Huntington's disease gene carriers with a mean estimated 90% probability of 25 years before the predicted onset of clinical symptoms. We show bidirectional changes in PDE10A expression in premanifest Huntington's disease gene carriers, which are associated with the probability of symptomatic onset. PDE10A expression in early premanifest Huntington's disease was decreased in striatum and pallidum and increased in motor thalamic nuclei, compared to a group of matched healthy controls. Connectivity-based analysis revealed prominent PDE10A decreases confined in the sensorimotor-striatum and in striatonigral and striatopallidal projecting segments. The ratio between higher PDE10A expression in motor thalamic nuclei and lower PDE10A expression in striatopallidal projecting striatum was the strongest correlate with higher probability of symptomatic conversion in early premanifest Huntington's disease gene carriers. Our findings demonstrate in vivo, a novel and earliest pathophysiological mechanism underlying Huntington's disease with direct implications for the development of new pharmacological treatments, which can promote neuronal survival and improve outcome in Huntington's disease gene carriers.

Cognitive impairment associated with schizophrenia is a key predictor of functional outcomes. The FDA-accepted MATRICS Consensus Cognitive Battery (MCCB) is held to be the gold standard measure but there are concerns about its ease of administration, reliance on language causing problems with translation and possible practice effects. The CogState Schizophrenia Battery (SB) is suggested as a non-language-based alternative but there is no substantial, independent comparison. The objective of this study was to assess the reliability and validity of these two assessment batteries. One hundred forty-three participants with DSM-IV schizophrenia and schizoaffective disorder were recruited into three similar studies. Each study administered MCCB and SB tests on consecutive days (baseline 1 and 2) and follow-up 3–4 weeks later. Batteries’ test-retest reliability was similar: SB composites correlated r = 0.66–0.78 between baselines, MCCB domains r = 0.69–0.90. Baseline 2 and follow-up SB composites correlated r = 0.65–0.80 and MCCB domains r = 0.62–0.87. MCCB tasks’ practice effects (Glass’ ∆ = 0.02–0.46) exceeded SB’s (Glass’ ∆ = 0.02–0.34). While the batteries’ total scores correlated strongly (r = 0.79–0.82), apparently equivalent cognitive domains on each battery (e.g. psychomotor-attention) correlated r = 0.22–0.60, indicating substantial differences between some supposed counterparts. Clinical trials using either battery would benefit from initial practice sessions to ameliorate practice effects but the SB may be more suitable to measure change in the absence of repeated baselines. The MCCB domains’ better correlations with social skills performance suggest that it may have an advantage for measuring cognition in relation to functional outcome.

Psychotic illnesses show variable responses to treatment. Determining the neurobiology underlying this is important for precision medicine and the development of better treatments. It has been proposed that dopaminergic differences underlie variation in response, with striatal dopamine synthesis capacity (DSC) elevated in responders and unaltered in non-responders. We therefore aimed to test this in a prospective cohort, with a nested case-control comparison. 40 volunteers (26 patients with first-episode psychosis and 14 controls) received an 18F-DOPA Positron Emission Tomography scan to measure DSC (Kicer) prior to antipsychotic treatment. Clinical assessments (Positive and Negative Syndrome Scale, PANSS, and Global Assessment of Functioning, GAF) occurred at baseline and following antipsychotic treatment for a minimum of 4 weeks. Response was defined using improvement in PANSS Total score of >50%. Patients were followed up for at least 6 months, and remission criteria applied. There was a significant effect of group on Kicer in associative striatum (F(2, 37) = 7.9, p = 0.001). Kicer was significantly higher in responders compared with non-responders (Cohen’s d = 1.55, p = 0.01) and controls (Cohen’s d = 1.31, p = 0.02). Kicer showed significant positive correlations with improvements in PANSS-positive (r = 0.64, p

Perinatal brain injuries, including hippocampal lesions, cause lasting changes in dopamine function in rodents, but it is not known if this occurs in humans. We compared adults who were born very preterm with perinatal brain injury to those born very preterm without perinatal brain injury, and age-matched controls born at full term using [18F]-DOPA PET and structural MRI. Dopamine synthesis capacity was reduced in the perinatal brain injury group relative to those without brain injury (Cohen’s d = 1.36, p=0.02) and the control group (Cohen’s d = 1.07, p=0.01). Hippocampal volume was reduced in the perinatal brain injury group relative to controls (Cohen’s d = 1.17, p=0.01) and was positively correlated with striatal dopamine synthesis capacity (r = 0.344, p=0.03). This is the first evidence in humans linking neonatal hippocampal injury to adult dopamine dysfunction, and provides a potential mechanism linking early life risk factors to adult mental illness., eLife digest Thirteen million infants are born too early every year. Improved care allows many to survive, but these “preterm infants” still face an increased risk of death and many other complications. Infants born very early, before 32 weeks, are at risk of brain injury because the brain is normally still developing in the later stages of pregnancy. They also have an increased risk of developing mental health problems later in life. Early-life brain injuries in rats cause changes in the production of a chemical called dopamine. Dopamine is a chemical messenger in the brain that reinforces rewarding behaviour. People with schizophrenia and attention deficit hyperactivity disorder (ADHD) have abnormal levels of dopamine. Changes in brain dopamine levels may explain why early-life brain injury is linked to later mental illness. But first scientists must study whether similar changes occur in humans with an early-life brain injury. Now, Froudist-Walsh et al. use brain imaging to show that people born very early who suffered a brain injury have lower dopamine levels than other adults. Imaging techniques were used to scan the brains of 13 adults who were born before 32 weeks and who had a brain injury around birth, 13 adults born before 32 weeks without a brain injury, and 13 adults born at “full term” (around 39 to 40 weeks). Individuals with low dopamine levels reported difficulty concentrating and a lack of motivation and enjoyment in their lives. Both can be warning signs of mental health problems. People born prematurely without a brain injury had normal dopamine levels and did not report such symptoms. More studies may help scientists understand how early brain injuries may cause brain chemical differences later in life, and how these brain changes affect individual’s mental health. They may also help scientists develop treatments to prevent or treat mental illness in people who experienced a brain injury after a very early birth.

BackgroundPatients with schizophrenia have substantially reduced subjective well-being (SW) compared to healthy individuals. It has been suggested that diminished SW may be related to deficits in the neural processing of reward but this has not been shown directly. We hypothesized that, in schizophrenia, lower SW would be associated with attenuated reward-related activation in the reward network.MethodTwenty patients with schizophrenia with a range of SW underwent a functional magnetic resonance imaging (fMRI) reward task. The brain activity underlying reward anticipation and outcome in schizophrenia was examined and compared to that of 12 healthy participants using a full factorial analysis. Region of interest (ROI) analyses of areas within the reward network and whole-brain analyses were conducted to reveal neural correlates of SW.ResultsReward-related neural activity in schizophrenia was not significantly different from that of healthy participants; however, the patients with schizophrenia showed significantly diminished SW. Both ROI and whole-brain analyses confirmed that SW scores in the patients correlated significantly with activity, specifically in the dorsal anterior cingulate cortex (dACC), during both reward anticipation and reward outcome. This association was not seen in the healthy participants.ConclusionsIn patients with schizophrenia, reduced activation of the dACC during multiple aspects of reward processing is associated with lower SW. As the dACC has been widely linked to coupling of reward and action, and the link to SW is apparent over anticipation and outcome, these findings suggest that SW deficits in schizophrenia may be attributable to reduced integration of environmental rewarding cues, motivated behaviour and reward outcome.

Background Increasing evidence suggests that antipsychotic drugs (APD) might affect brain structure directly, particularly the cerebral cortex. However, the precise anatomical loci of these effects and their underlying cellular basis remain unclear. Methods With ex vivo magnetic resonance imaging in rats treated chronically with APDs, we used automated analysis techniques to map the regions that show maximal impact of chronic (8 weeks) treatment with either haloperidol or olanzapine on the rat cortex. Guided by these imaging findings, we undertook a focused postmortem investigation with stereology. Results We identified decreases in the volume and thickness of the anterior cingulate cortex (ACC) after chronic APD treatment, regardless of the APD administered. Postmortem analysis confirmed these volumetric findings and demonstrated that chronic APD treatment had no effect on the total number of neurons or S100β+ astrocytes in the ACC. In contrast, an increase in the density of these cells was observed. Conclusions This study demonstrates region-specific structural effects of chronic APD treatment on the rat cortex, primarily but not exclusively localized to the ACC. At least in the rat, these changes are not due to a loss of either neurons or astrocytes and are likely to reflect a loss of neuropil. Although caution needs to be exerted when extrapolating results from animals to patients, this study highlights the power of this approach to link magnetic resonance imaging findings to their histopathological origins.

Background: Cannabis is the most widely used illicit drug globally, and users are at increased risk of mental illnesses including psychotic disorders such as schizophrenia. Substance dependence and schizophrenia are both associated with dopaminergic dysfunction. It has been proposed, although never directly tested, that the link between cannabis use and schizophrenia is mediated by altered dopaminergic function. Methods: We compared dopamine synthesis capacity in 19 regular cannabis users who experienced psychotic-like symptoms when they consumed cannabis with 19 nonuser sex- and age-matched control subjects. Dopamine synthesis capacity (indexed as the influx rate constant Kicer) was measured with positron emission tomography and 3,4-dihydroxy-6-[18F]-fluoro-l-phenylalanine ([18F]-DOPA). Results: Cannabis users had reduced dopamine synthesis capacity in the striatum (effect size: .85; t36 = 2.54, p = .016) and its associative (effect size: .85; t36 = 2.54, p = .015) and limbic subdivisions (effect size: .74; t36 = 2.23, p = .032) compared with control subjects. The group difference in dopamine synthesis capacity in cannabis users compared with control subjects was driven by those users meeting cannabis abuse or dependence criteria. Dopamine synthesis capacity was negatively associated with higher levels of cannabis use (r = −.77, p < .001) and positively associated with age of onset of cannabis use (r = .51, p = .027) but was not associated with cannabis-induced psychotic-like symptoms (r = .32, p = .19). Conclusions: These findings indicate that chronic cannabis use is associated with reduced dopamine synthesis capacity and question the hypothesis that cannabis increases the risk of psychotic disorders by inducing the same dopaminergic alterations seen in schizophrenia.

Large placebo response presents a major challenge for psychopharmacologic drug development and contributes to the increasing failure of psychiatric trials. The objective of this meta-regression analysis was to identify potential contributors to placebo response in randomized controlled trials of antipsychotic treatment in schizophrenia.The authors extracted trial design and clinical variables from eligible randomized controlled trials (N=50) identified through searches of MEDLINE (1960-2010) and other sources. Standardized mean change (SMC) was used as the effect size measure for placebo response, based on change scores on the Brief Psychiatric Rating Scale or the Positive and Negative Syndrome Scale from baseline to endpoint (2 to 12 weeks).The results suggest significant heterogeneities (Q=387.83, df=49) in the magnitude of placebo response (mean SMC, -0.33, range -1.4 to 0.9) and in study quality. Both placebo SMC and study quality increased over time. Younger age, shorter duration of illness, greater baseline symptom severity, and shorter trial duration were significantly associated with greater placebo response, while country (United States compared with other countries) was not. More study sites, fewer university or Veterans Affairs treatment settings, and a lower percentage of patients assigned to receive placebo were associated with a greater placebo response, but these were not independent of publication year. Study quality affected the variability but not mean levels of placebo response.This study identified important patient characteristics and trial design factors affecting the level of placebo response and hence the likelihood of detecting efficacy signals in randomized controlled trials. Future studies should test whether controlling these factors improves the detection of an antipsychotic effect.

The aim of this study was to determine what variables predict a 'combined treatment outcome' (COMBOUT) in patients with chronic schizophrenia.This analysis (n=522) was based on a randomized, double-blind, flexible-dose, 12-week study that enrolled chronically-ill patients diagnosed with schizophrenia or a related disorder. COMBOUT was assessed using the PANSS for symptoms, CGI-S for overall clinical status, MADRS for depressive symptoms, QLS for functioning/QOL, and SWN-K for subjective well-being. Possible predictors included demographics as well as baseline scores (Model I), and early change (week 2) scores (Model II).Model I: significantly better outcome (higher COMBOUT score) was observed in patients with lower MADRS (T= - 6.36; p0.001) or higher QLS (T=5.05; p0.001) scores at baseline. Model II: significantly better COMBOUT was observed in patients with early improvement of QLS (T=4.93; p0.001), SWN-K (T=3.88; p0.001), PANSS (T= - 2.32; p=0.021) and CGI-S scores (T= - 2.22; p=0.027). Changes in EPS were not predictors of COMBOUT in the models tested.COMBOUT at endpoint was predicted by lower depressive symptom score and higher QOL at baseline and by early improvement in psychopathology, quality of life and subjective well-being.

BackgroundClozapine is the only antipsychotic drug licensed for treatment-resistant schizophrenia but its use is often delayed. Since previous studies, national guidelines on the use of clozapine and other antipsychotics have been disseminated to clinicians.AimsTo determine the theoretical delay to clozapine initiation and to quantify the prior use of antipsychotic polypharmacy and high-dose antipsychotic treatment.MethodClinico-demographic data were extracted from the treatment records of all patients commencing clozapine in our centre between 2006 and 2010.ResultsComplete records were available for 149 patients. The mean theoretical delay in initiating clozapine was 47.7 months (s.d. = 49.7). Before commencing clozapine, antipsychotic polypharmacy and high-dose treatment was evident in 36.2 and 34.2% of patients respectively. Theoretical delay was related to illness duration (β = 0.7, PConclusionsSubstantial delays to clozapine initiation remain and antipsychotic polypharmacy and high doses are commonly used prior to clozapine, despite treatment guidelines.

Elevated presynaptic striatal dopaminergic function is a robust feature of schizophrenia. However, the relationship between this dopamine abnormality and the response to dopamine-blocking antipsychotic treatments is unclear. The authors tested the hypothesis that in patients with schizophrenia the response to antipsychotic treatment would be related to the severity of presynaptic dopamine dysfunction, as indexed using [(18)F]-DOPA uptake positron emission tomography (PET).Twelve patients with treatment-resistant schizophrenia, twelve patients with schizophrenia who had responded to antipsychotics, and twelve healthy volunteers matched for gender, age, ethnicity, weight, and cigarette smoking underwent [(18)F]-DOPA PET scanning. [(18)F]-DOPA influx rate constants (K(i)(cer) values) were measured in the striatum and its functional subdivisions.Patients who had responded to antipsychotic treatment showed significantly higher K(i)(cer) striatal values than did patients with treatment-resistant illness (effect size=1.11) and healthy volunteers (effect size=1.12). The elevated [(18)F]-DOPA uptake was most marked in the associative (effect size=1.31) and the limbic (effect size=1.04) striatal subdivisions. There were no significant differences between patients with treatment-resistant illness and healthy volunteers in the whole striatum or any of its subdivisions.In some patients with schizophrenia, antipsychotic treatment may be ineffective because they do not exhibit the elevation in dopamine synthesis capacity that is classically associated with the disorder; this may reflect a different underlying pathophysiology or a differential effect of antipsychotic treatment.

Connectomic approaches using diffusion tensor imaging have contributed to our understanding of brain changes in psychosis, and could provide further insights into the neural mechanisms underlying response to antipsychotic treatment. We here studied the brain network organization in patients at their first episode of psychosis, evaluating whether connectome-based descriptions of brain networks predict response to treatment, and whether they change after treatment. Seventy-six patients with a first episode of psychosis and 74 healthy controls were included. Thirty-three patients were classified as responders after 12 weeks of antipsychotic treatment. Baseline brain structural networks were built using whole-brain diffusion tensor imaging tractography, and analysed using graph analysis and network-based statistics to explore baseline characteristics of patients who subsequently responded to treatment. A subgroup of 43 patients was rescanned at the 12-week follow-up, to study connectomic changes over time in relation to treatment response. At baseline, those subjects who subsequently responded to treatment, compared to those that did not, showed higher global efficiency in their structural connectomes, a network configuration that theoretically facilitates the flow of information. We did not find specific connectomic changes related to treatment response after 12 weeks of treatment. Our data suggest that patients who have an efficiently-wired connectome at first onset of psychosis show a better subsequent response to antipsychotics. However, response is not accompanied by specific structural changes over time detectable with this method.

Summary Background Many patients with schizophrenia require high doses of medication for their ongoing psychotic symptoms. Glutamate theories and findings from studies showing efficacy of sarcosine, an endogenous, non-selective glycine-reuptake inhibitor mediated by GlyT1, offer an alternative approach. We undertook the SearchLyte trial programme to examine the efficacy of bitopertin, a selective GlyT1-mediated glycine-reuptake inhibitor, as an adjunctive treatment to ongoing antipsychotic treatment. Methods SearchLyte consisted of three phase 3, randomised, double-blind, parallel-group, placebo-controlled, multicentre studies done in outpatient clinics in Asia, Europe, and North and South America (TwiLyte done at 109 sites, NightLyte at 84, and MoonLyte at 87). Participants were male and female outpatients, aged at least 18 years, meeting DSM-IV criteria for schizophrenia with suboptimally controlled positive symptoms despite treatment with antipsychotics. Inclusion criteria included a Positive and Negative Syndrome Scale (PANSS) total score of at least 70 and antipsychotic treatment stability for the past 12 weeks before randomisation. Key exclusion criteria included meeting criteria for symptomatic remission or previous treatment with a GlyT1 inhibitor or any other investigational drug. After a screening or 4-week prospective stabilisation period, we randomly assigned participants (1:1:1) to a 12-week, double-blind treatment of either placebo or one of two fixed doses of oral, once-daily bitopertin (10 or 20 mg in TwiLyte and NightLyte; 5 or 10 mg in MoonLyte) added to their current antipsychotic medicine. After completion of 12 weeks' treatment, the study design allowed for additional double-blind treatment for 40 weeks to assess maintenance of the effect, followed by a randomised 4-week washout period to assess withdrawal effects. Subsequently, all patients were offered the opportunity to receive bitopertin treatment in a 3-year follow-up. The primary efficacy endpoint was the mean change from baseline in the PANSS Positive Symptom Factor Score (PSFS) at week 12, analysed in the modified intention-to-treat population. The trials were registered at ClinicalTrials.gov (numbers NCT01235520 [TwiLyte], NCT01235585 [MoonLyte], and NCT01235559 [NightLyte]). Findings Between Nov 19, 2010, and Dec 12, 2014, we randomly assigned 1794 patients to treatment, of whom 1772 were treated and analysed. MoonLyte was discontinued in September, 2014, on the basis of results from futility analyses. Across studies and treatment arms, most patients completed 12 weeks of treatment (505 in TwiLyte, 517 in NightLyte, and 506 in MoonLyte). Only one study, NightLyte, met the primary endpoint where the PANSS PSFS significantly differed from placebo at week 12, and only in the 10-mg arm: mean difference in score −1·37, 95% CI −2·27 to −0·47; p=0·0028. Improvements from baseline for the bitopertin 20-mg arm in Nightlyte were not significant compared with placebo: −3·77, 95% CI −4·40 to −3·14; p=0·3142. Results from the other two studies also did not differ from placebo (TwiLyte 0·58, 95% CI −0·34 to 1·50, p=0·22 for 10 mg and 0·43, −0·49 to 1·36, p=0·36 for 20 mg; MoonLyte 0·06, 95% CI −0·79 to 0·92, p=0·88 for 5 mg and 0·44, −0·41 to 1·28, p=0·31 for 10 mg). Placebo responses varied across studies and might have contributed to the differences in efficacy between studies. Four deaths occurred during the 12-week treatment period, three in NightLyte (upper gastrointestinal haemorrhage, alcohol poisoning and related head injury, and a completed suicide) and one in MoonLyte (myocardial infarction in a patient with pre-existing risk factors). Only the death by suicide was deemed related to the study drug. The incidence of serious adverse events was low across treatment groups in all three studies; psychiatric disorders were the most frequently reported serious adverse events and the most frequent cause of adverse events leading to discontinuation. Interpretation Only one of six active treatment arms across the three studies offered an advantage of adjunctive bitopertin over placebo for the treatment of suboptimally controlled symptoms of schizophrenia. The small improvement associated with bitopertin together with the varying placebo response suggests that adjunctive bitopertin treatment might offer only modest benefit to suboptimal responders to antipsychotics, if any. Funding F Hoffmann-La Roche.

Phosphodiesterase 10A (PDE10A) is an enzyme present in striatal medium spiny neurons that degrades the intracellular second messengers triggered by dopamine signaling. The pharmaceutical industry has considerable interest in PDE10A inhibitors because they have been shown to have an antipsychotic-like effect in animal models. However, the status of PDE10A in schizophrenia is unknown. Using a newly developed and validated radioligand, [(11)C]IMA107, the authors report the first in vivo assessment of PDE10A brain expression in patients with schizophrenia.The authors compared PDE10A availability in the brains of 12 patients with chronic schizophrenia and 12 matched healthy comparison subjects using [(11)C]IMA107 positron emission tomography (PET). Regional estimates of the binding potential (BPND) of [(11)C]IMA107 were generated from dynamic PET scans using the simplified reference tissue model with the cerebellum as the reference tissue for nonspecific binding.There was no significant difference in [(11)C]IMA107 BPND between schizophrenia patients and comparison subjects in any of the brain regions studied (thalamus, caudate, putamen, nucleus accumbens, globus pallidus, and substantia nigra). There was also no significant correlation between [(11)C]IMA107 BPND and the severity of psychotic symptoms or antipsychotic dosage.Patients with schizophrenia have normal availability of PDE10A in brain regions thought to be involved in the pathophysiology of this disorder. The findings do not support the proposal of an altered PDE10A availability in schizophrenia. The implication of this finding for future drug development is discussed.

A recent single-site study (Fisher et al., 2009. Am J Psychiatry. 166 (7) 805-11) showed that repeated training with the Brain Fitness Program (BFP) improved performance on a battery of neuropsychological tasks. If replicated these data suggest an important non-pharmacological method for ameliorating cognitive impairment in schizophrenia. Our study evaluated the BFP training effects in an open-label, multi-site, multinational clinical trial. Fifty-five stable adult patients with schizophrenia on regular antipsychotic medication completed ≥ 32 BFP training sessions over 8-10 weeks. Training effects on cognitive performance and functional capacity outcome measures were measured using CogState® schizophrenia battery, UCSD Performance based Skills Assessment (UPSA-2) and Cognitive Assessment Interview (CAI). BFP training showed a large and significant treatment effect on a training exercise task (auditory processing speed), however this effect did not generalize to improved performance on independent CogState® assessment. There were no significant effects on UPSA-2 or CAI scores. Our study demonstrated the feasibility of implementing BFP training in a multi-site study. However, BFP training did not show significant treatment effects on cognitive performance or functional capacity outcome measures despite showing large and significant effects on a training exercise.

Background Various schizophrenic symptoms are suggested to be linked to a dysfunction of the brain reward system. Several studies have found alterations in the reward processing in patients with schizophrenia; however, most previous findings might be confounded by medication effects. Methods Thirty-one antipsychotic-naive schizophrenia patients and 31 age- and gender-matched healthy control subjects were examined with functional magnetic resonance imaging while playing a variant of the monetary incentive delay task. The task variant made it possible to separate overall salience (defined as arousing events) into behavioral salience (events where a predicted reward requires performance) and valence anticipation (the anticipation of a monetarily significant outcome) . Furthermore, the evaluation of monetary gain and loss was assessed. Results During reward anticipation, patients had a significant attenuation of the activation in ventral tegmentum, ventral striatum, and anterior cingulate cortex during presentation of salient cues. This signal attenuation in ventral striatum was correlated with the degree of positive symptoms. Signal attenuation was most pronounced for behavioral salience and nonsignificant for value anticipation. Furthermore, patients showed a changed activation pattern during outcome evaluation in right prefrontal cortex. Conclusion Our results suggest that changes during reward anticipation in schizophrenia are present from the beginning of the disease. This supports a possible involvement of reward disturbances in the pathophysiology of schizophrenia. The most pronounced changes were seen in relation to overall salience. In ventral striatum these changes were associated with the degree of positive symptoms.

Antipsychotic drugs act on the dopaminergic system (first-generation antipsychotics, FGA), but some also directly affect serotonergic function (second-generation antipsychotics, SGA) in the brain. Short and long-term effects of these drugs on brain physiology remain poorly understood. Moreover, it remains unclear whether any physiological effect in the brain may be different for FGAs and SGAs. Immediate (+3.30 h) and different effects of single-dose FGA (haloperidol, 3 mg) and a SGA (aripiprazole, 10 mg) on resting cerebral blood flow (rCBF) were explored in the same 20 healthy volunteers using a pulsed continuous arterial spin labeling (pCASL) sequence (1.5T) in a placebo-controlled, repeated measures design. Both antipsychotics increased striatal rCBF but the effect was greater after haloperidol. Both decreased frontal rCBF, and opposite effects of the drugs were observed in the temporal cortex (haloperidol decreased, aripiprazole increased rCBF) and in the posterior cingulate (haloperidol increased, aripiprazole decreased rCBF). Further increases were evident in the insula, hippocampus, and anterior cingulate after both antipsychotics, in the motor cortex following haloperidol and in the occipital lobe the claustrum and the cerebellum after aripiprazole. Further decreases were observed in the parietal and occipital cortices after aripiprazole. This study suggests that early and different rCBF changes are evident following a single-dose of FGA and SGA. The effects occur in healthy volunteers, thus may be independent from any underlying pathology, and in the same regions identified as structurally and functionally altered in schizophrenia, suggesting a possible relationship between antipsychotic-induced rCBF changes and brain alterations in schizophrenia. Hum Brain Mapp, 2013. (C) 2012 Wiley Periodicals, Inc.

Evidence linking schizophrenia to alterations in presynaptic dopamine (DA) grows, although treatments to date have largely focused on postsynaptic D2 receptor blockade. This study examined augmenting response in treatment-resistant schizophrenia through the addition of tetrabenazine (TBZ), a presynaptic vesicular monoamine transporter (VMAT2) inhibitor. Participants included 41 outpatients (mean age, 43.5 years) with treatment-refractory schizophrenia, stabilized on their present antipsychotic treatment (clozapine, 73%) for more than 3 months. Individuals were randomly assigned to TBZ augmentation (12.5-75 mg/d), titrated according to a fixed, flexible schedule, or placebo over 12 weeks. Twenty subjects received TBZ, and 21 received placebo; doses of 18 of the 20 TBZ-treated individuals were titrated up to the maximum of 75 mg/d, and 16 (80%) of them completed the trial. Tetrabenazine was well tolerated and not linked to increased adverse effects, including those that have been reported more frequently (eg, parkinsonism, depression, and sedation) with higher doses (>100 mg/d) used in the treatment of hyperkinetic movement disorders. However, there was no indication of clinical improvement as measured using the Brief Psychiatric Rating Scale, the Clinical Global Impression scale, and the Global Assessment of Functioning scale. In examining those receiving TBZ-clozapine specifically, there was no indication of drug-drug interactions or difference in response compared to the overall sample. Tetrabenazine was not effective, as used here, in augmenting clinical response in treatment-resistant schizophrenia. It may be premature, however, to discount the potential benefits of VMAT2 inhibitors in treating psychosis in light of what is presently understood regarding presynaptic DA's role and evidence that "endogenous sensitization" may occur over the course of the illness.

BackgroundTo date, magnetic resonance imaging (MRI) has made little impact on the diagnosis and monitoring of psychoses in individual patients. In this study, we used a support vector machine (SVM) whole-brain classification approach to predict future illness course at the individual level from MRI data obtained at the first psychotic episode.MethodOne hundred patients at their first psychotic episode and 91 healthy controls had an MRI scan. Patients were re-evaluated 6.2 years (s.d.=2.3) later, and were classified as having a continuous, episodic or intermediate illness course. Twenty-eight subjects with a continuous course were compared with 28 patients with an episodic course and with 28 healthy controls. We trained each SVM classifier independently for the following contrasts: continuous versus episodic, continuous versus healthy controls, and episodic versus healthy controls.ResultsAt baseline, patients with a continuous course were already distinguishable, with significance above chance level, from both patients with an episodic course (p=0.004, sensitivity=71, specificity=68) and healthy individuals (p=0.01, sensitivity=71, specificity=61). Patients with an episodic course could not be distinguished from healthy individuals. When patients with an intermediate outcome were classified according to the discriminating pattern episodic versus continuous, 74% of those who did not develop other episodes were classified as episodic, and 65% of those who did develop further episodes were classified as continuous (p=0.035).ConclusionsWe provide preliminary evidence of MRI application in the individualized prediction of future illness course, using a simple and automated SVM pipeline. When replicated and validated in larger groups, this could enable targeted clinical decisions based on imaging data.

Research has identified distinct trajectories of antipsychotic response in patients with chronic schizophrenia in short-duration trials (~12 weeks). This post-hoc analysis identified trajectories in patients with chronic schizophrenia treated for ≤24 weeks. We pooled data from 1990 patients with chronic schizophrenia from 6 randomized, double-blind, olanzapine-comparator trials of atypical antipsychotics. Trajectory analysis identified homogeneous subpopulations within the larger heterogeneous population. Baseline demographics were compared between the identified latent classes. Five distinct response trajectories based on Positive and Negative Syndrome Scale (PANSS) Total score were identified: Dramatic Responders (n=47/1990, 2.4%), severely-ill patients (PANSS=124) with rapid and sustained improvement (51%) by Week 3; Partial Responders (n=1802/1990, 90.6%), moderately-ill (PANSS=90) with minimal improvement (21%) by Week 4, and little further improvement; Partial Responders-Unsustained (Late) (n=32/1990, 1.6%), markedly-ill (PANSS=95) with minimal initial improvement followed by worsening after Week 12; Partial Responders-Unsustained (Early) (n=28/1990, 1.4%), markedly-ill (PANSS=102) with minimal initial improvement followed by worsening after Week 8; and Delayed Responders (n=81/1990, 4.1%), markedly-to-severely-ill (PANSS=113) with minimal (11%) improvement at Week 8, but noticeable improvement thereafter (49%). Significant differences were noted for several baseline characteristics (p

Dopamine D2 receptor occupancy of antipsychotic drugs is calculated relative to the subject's D2 receptor binding potential (BP) in the drug-free state (baseline BP). Because baseline BP is seldom known in patients with schizophrenia, population means from unrelated control samples are often used to estimate it. However, this is likely to introduce bias and error into the occupancy measure. There is thus a need for a method to reliably estimate baseline BP for patient populations in whom it may be impractical or unethical to get baseline measurements. It has been previously found that the relationship between plasma concentration and dopamine receptor occupancy by antipsychotic drugs follows a sigmoid Emax model. Based on this, we developed a method for calculating dopamine D2 receptor occupancy by antipsychotic drugs using an inhibitory Emax model ( Imax method) that estimates individual baseline BPs. To validate this, we compared the result from the Imax method with actual occupancy and estimated occupancy calculated from the average baseline BP (substitution method). The data for validation were obtained from two different receptor occupancy studies with the antipsychotic medications YKP1358 and aripiprazole. We estimated the reliability between the true measured occupancy and the predicted occupancy using the intraclass correlation coefficient (ICC), and the variability of occupancy was also compared between the Imax and substitution methods. In YKP1358 study, all the ICCs of the Imax method were above 0.8, but those of the substitution method showed values lower than 0.8. In aripiprazole study, the ICCs of the Imax method were higher than those of the substitution method, but all the ICCs showed higher values than 0.8. The variability of Imax method was significantly smaller than that of substitution method in both studies. The Imax method shows better reliability and less variability than the substitution method. The Imax method can be applied for receptor occupancy study, and bring more reliability and accuracy to the occupancy study in patients with schizophrenia.

Objective: Early, effective treatment in first-episode schizophrenia is advocated, although evidence based on a systematic approach over multiple antipsychotic trials is lacking. Employing a naturalistic design, we examined response rates over 3 circumscribed antipsychotic trials. Method: Between June 2003 and December 2008, 244 individuals with first-episode schizophrenia or schizoaffective disorder according to DSM-IV criteria were treated at the Centre for Addiction and Mental Health,Toronto, Ontario, Canada, following an algorithm that moved them through 2 antipsychotic trials, followed by a trial with clozapine. For the first 2 trials, treatment consisted of risperidone followed by olanzapine, or vice versa; each trial consisted of 3 stages (low-, full-, or high-dose) lasting up to 4 weeks at each level and adjusted according to response/tolerability. Clinical response was defined as a Clinical Global Impressions-Improvement score of 2 (much improved) or 1 (very much improved) and/or a Brief Psychiatric Rating Scale Thought Disorder subscale score

Objective To assess the relationships among quetiapine blood concentration, daily dose, dopamine receptor occupancy, and clinical outcome in order, if possible, to define a target plasma level range in which therapeutic response is enhanced and adverse events are minimized. Data sources A search of the database Embase from 1974 to March 2009 and the databases MEDLINE and PubMed from 1966 to March 2009 was conducted. The drug name quetiapine was searched with each of the terms plasma levels, plasma concentration, therapeutic drug monitoring, and dopamine occupancy. Study selection The search uncovered 42 relevant articles. All published reports of quetiapine plasma or serum concentration were considered for inclusion if reported in relation to a dose, clinical outcome, or dopamine occupancy. After application of exclusion criteria, 20 articles remained. Data extraction Trials designed primarily to investigate an interaction between quetiapine and another medication were excluded, as were those designed to compare methods of blood sample analysis. Data synthesis There was a weak correlation between quetiapine dose and measured plasma concentration (from trough samples). Quetiapine dose was correlated with central dopamine D(2) occupancy, although the relationship between plasma level and D(2) occupancy is less clear. Conclusions The dose-response relationship for (immediate-release) quetiapine is established. Data on plasma concentration-response relationships are not sufficiently robust to allow determination of a therapeutic plasma level range for quetiapine. Therapeutic drug monitoring procedures are thus probably not routinely useful in optimizing quetiapine dose. Further examination of the relationship between peak quetiapine plasma concentration and clinical response is necessary.

The main ingredient in cannabis, Δ9-tetrahydrocannabinol (THC), can elicit acute psychotic reactions in healthy individuals and precipitate relapse in schizophrenic patients. However, the neural mechanism of this is unknown. We tested the hypothesis that THC psychopathology is related to changes in electroencephalography (EEG) power or inter-regional coherence. In a within-subjects design, participants (n=16) were given intravenous THC (1.25 mg) or placebo under double-blind conditions, during EEG recordings. Using fast-Fourier transform, EEG data were analyzed for power and coherence in the delta (1–3.5 Hz), theta (3.5–7 Hz), alpha (8–13 Hz), beta (14–25 Hz), low-gamma (30–40 Hz), and high-gamma (60–70 Hz) bands during engagement in the n-back test of working memory (WM). Compared with placebo, THC evoked positive and negative psychotic symptoms, as measured by the positive and negative syndrome scale (p

While dopamine D2 receptor partial agonists (PAs) have been long considered for treating schizophrenia, only one, aripiprazole, is clinically available for therapeutic use. This raises critically important questions as to what is unique about aripiprazole and to what extent animal models can predict therapeutic success. A number of PAs whose clinical fate is known: aripiprazole, preclamol, terguride, OPC-4392 and bifeprunox were compared to haloperidol (a reference antipsychotic) in several convergent preclinical animal models; i.e. amphetamine-induced locomotion (AIL) and conditioned avoidance response (CAR), predictive of antipsychotic effects; unilateral nigrostriatal lesioned rats, a model of hypo-dopaminergia; striatal Fos induction, a molecular marker for antipsychotic activity; and side-effects common to this class of drugs: catalepsy (motor side-effects) and prolactaemia. The results were compared across drugs with reference to their measured striatal D2 receptor occupancy. All the PAs occupied striatal D2 receptors in a dose dependent manner, inhibited AIL and CAR, and lacked motor side-effects or prolactinaemia despite D2 receptor occupancy exceeding 80%. At comparative doses, aripiprazole distinguished itself from the other PAs by causing the least rotation in the hypo-dopaminergic model (indicating the least intrinsic activity) and showed the highest Fos expression in the nucleus accumbens (indicating functional D2 antagonism). Although a number of PAs are active in antipsychotic animal models, not all of them succeed. Given that only aripiprazole is clinically available, it can be inferred that low functional intrinsic activity coupled with sufficient functional antagonism as reflected in the animal models may be a marker of success.

Extended placebo-controlled clinical trials in schizophrenia research pose an ethical challenge. This study examines factors that have implications for the design and duration of placebo-controlled acute efficacy trials: Does early response discriminate active drug (AD) from placebo, and are the early differences sustained over time? A post hoc pooled analysis of 2 randomized 6-week double-blind clinical trials was performed comparing patients with schizophrenia treated with placebo or low-dose olanzapine (1 mg/d; placebo/low dose [PBO] group, n = 170) to patients treated with a 10- to 20-mg/d dose of haloperidol or medium- to high-dose olanzapine (7.5 to 17.5 mg/d; AD group, n = 252). Mixed-model repeated-measure analysis tested for group differences. Power analysis was undertaken to compare study designs with shorter durations. At 2 weeks, the mean reduction in the Brief Psychiatric Rating Scale total score was significantly greater for the AD group (-10.1) compared with the PBO group (-4.1; P < 0.001); this difference was sustained until the study ended (6 weeks). A higher proportion of early treatment responders were observed for the AD group (52%) compared with the PBO group (29%; P < 0.001). Early nonresponse to placebo or drug was predictive of subsequent nonresponse (negative predictive value: PBO = 95%, AD = 84%). Power analysis indicates that the placebo-drug differences are robust at 2 weeks. Treatment responders from the AD and the PBO groups followed a similar response path. Early response to antipsychotic treatment discriminated AD from placebo. Reducing placebo-controlled clinical trials from 6 weeks to 2 to 4 weeks was found to be a viable option for efficacy identification in acutely ill patients.

To assess rapid antipsychotic efficacy with oral ziprasidone monotherapy in bipolar acute manic/mixed episodes with psychotic features, and predictive value of rapid antipsychotic response for subsequent acute manic/mixed episode remission.Pooled analysis of two 3-week, randomized, double-blind, placebo-controlled trials of ziprasidone (40-160mg/d) in inpatients with bipolar I disorder, and a current manic or mixed episode, with (n=152) or without (n=246) psychotic features. Psychosis improvement was evaluated by change in SADS-C psychosis score (sum of delusions, hallucinations, and suspiciousness items). Rapid antipsychotic response (or=50% decrease in SADS-C psychosis score by Day 4) and acute manic episode response and remission (endpointor=50% MRS decrease, and a MRS scoreor=12, respectively) were analyzed.Significantly greater antipsychotic effects were observed by Day 4 with ziprasidone treatment (vs. placebo) and the magnitude of improvement increased significantly with time, in all subjects, in the subgroup of all psychotic subjects, and psychotic subjects with low baseline agitation (p0.05). Rapid antipsychotic response predicted subsequent acute manic episode remission independent of ziprasidone or placebo treatment received (p0.001, ROC AUC=0.71) with significant improvement in accuracy of MRS remission prediction when compared to models using early changes in MRS score alone (p=0.01).Post hoc analysis, use of 3 SADS-C psychosis items to assess psychosis.The predictive value of rapid (Day 4) improvement in psychotic symptoms for subsequent (Day 21) remission of acute manic/mixed symptoms may facilitate enhanced therapeutics, in view of the current practice of brief hospitalization for patients with acute manic/mixed episodes with psychotic features.

Our objective was to prospectively assess whether early (ie, 2 weeks) response to an antipsychotic predicts later (12-week) response and whether 'switching' early non-responders to another antipsychotic is a better strategy than 'staying'. This randomized, double-blind, flexible-dosed, 12-week study enrolled 628 patients diagnosed with schizophrenia or schizoaffective disorder. All initiated treatment with risperidone. Early response was defined as > or =20% improvement on the Positive and Negative Syndrome Scale (PANSS) total score following 2 weeks of treatment. Early responders (ERs) continued on risperidone, whereas early non-responders (ENRs) were randomized (1 : 1) to continue on risperidone 2-6 mg/day or switch to olanzapine 10-20 mg/day for 10 additional weeks. Compared with ENRs, risperidone ERs showed significantly greater reduction in PANSS total score (end point; p

Tobacco dependence is highly prevalent in depressed patients. We assessed changes in [(11)C]-raclopride binding potential (BP) using positron emission tomography (PET) before and after the oral administration of d-amphetamine in healthy controls and unmedicated patients with current depression with and without current tobacco dependence. Over a single study day 2 [(11)C]-raclopride positron emission tomography scans were taken in 38 subjects: at baseline and 2 h following oral d-amphetamine 30 mg. Twenty controls (9 smokers, 11 nonsmokers) and 18 subjects with current major depressive episode (8 smokers, 10 non-smokers). Striatal [(11)C]-raclopride binding potential was measured before and after d-amphetamine administration. Depressed smokers had a lower baseline [(11)C]-raclopride binding potential compared with both control non-smokers (P < 0.007) and depressed non-smokers (P < 0.001). There was a main effect of smoking status on amphetamine-induced change in [(11)C]-raclopride binding potential (P < 0.02), but no main effect of depression. This may be due to a floor effect because of the low BP at baseline. Depressed subjects reported significant increase of positive mood after d-amphetamine administration compared with controls (depressed smokers vs. control smokers: P < 0.05; depressed non-smokers vs. controls: P < 0.055). Tobacco dependence appears to decrease d-amphetamine-induced changes in [(11)C]-raclopride binding potential as measured by positron emission tomography. Comorbid major depression and tobacco dependence exacerbates this effect, suggesting an altered dopamine system in comorbid patients.

Clinical trial data were evaluated for the association between 22 single-nucleotide polymorphisms (SNPs) and response in acutely ill patients diagnosed with schizophrenia, schizoaffective disorder or schizophreniform disorder, who were treated with oral risperidone. All patients in the exploratory (78 African Americans) and validation (65 whites) data sets received risperidone 2-6 mg per day over 2-12 weeks. Two SNPs were found to have significant associations with response to risperidone over 2-12 weeks in both African-American and white patients and had a consistent direction of effect in both cohorts. Metabotropic glutamate receptor (GRM3) SNP, rs724226, was associated with a change in the positive and negative syndrome scale (PANSS) total response. Catechol-O-methyltransferase (COMT) SNP, rs165599, was moderately associated with a change in the PANSS Negative score. The greater prevalence of poor-responder GRM3 and COMT alleles in white versus African-American patients might have a clinical significance in evaluating the ethnic-specific response to risperidone.

Objective It is generally held that the elderly are more sensitive to motor side effects of antipsychotics, although the mechanisms for such an effect are not fully understood. The objective of this study was to examine whether this sensitivity is due to a central pharmacokinetic (i.e., higher occupancy for a given plasma level) or pharmacodynamic (i.e., greater functional effects for a given occupancy) effect. Design Crosssectional. Setting Centre for Addiction and Mental Health, Toronto, Ontario, Canada. Participants Thirteen subjects aged 50 (mean ± standard deviation age: 62 ± 9 years) with schizophrenia or schizoaffective disorder who were receiving risperidone. Measurements Dopamine D 2 binding potential in the striatum, using [ 11 C]raclopride positron emission tomography scan. D 2 receptor occupancy was calculated, using age-corrected measure from healthy individuals and region of interest analysis. Results The authors observed the expected nonlinear relationship between total risperidone and 9-hydroxyrisperidone plasma level and striatal D 2 receptor occupancy. The estimated plasma level of risperidone plus 9-hydroxyrisperidone associated with 50% maximal receptor occupancy was 7.3 ng/mL, which is similar to what has been reported in younger patients. However, extrapyramidal side effects (EPS) were observed in seven subjects at D 2 occupancy of 34%–79%, occupancy levels that are lower than previously reported for younger patients in whom EPS are rare at occupancies lower than 80%. Conclusion The observation of greater functional effect (EPS in this case) for a given drug occupancy than the younger patients supports a pharmacodynamic mechanism for age-related antipsychotic drug sensitivity. This finding has important implications for dosing of antipsychotics in older patients with schizophrenia.

The dopamine D(2) receptors exist in two states: a high-affinity state (D(2)(high)) that is linked to second messenger systems, is responsible for functional effects, and exhibits high affinity for agonists; and a low-affinity state that is functionally inert and exhibits lower affinity for agonists. The dopamine D(3) receptors have high-affinity for agonist (eg dopamine) and the existence of the two affinity states is controversial. Although preclinical studies in animal models of psychosis have shown a selective increase of D(2)(high) as the common pathway to psychosis, the D(3) has been suggested to be involved in the pathophysiology of psychosis. We report the first study of the D(2)(high) and D(3) in schizophrenia using the novel PET radiotracer, [(11)C]-(+)-PHNO. We recruited 13 patients with schizophrenia-spectrum disorder amidst an acute psychotic episode, drug free for at least 2 weeks, and 13 age-sex-matched healthy controls. The binding potential no-displaceable (BP(ND)) was examine in the main regions of interest (caudate, putamen, ventral striatum, globus pallidus, substantia nigra, and anterior thalamus) and in a voxel-wise analysis. The BP(ND) between patients and controls was not different in any of the regions. The voxel-wise analysis did not reveal any difference and no correlations were found between the BP(ND) and positive and negative syndrome scale subscales. Our results do not find support for the hypothesis linking psychosis to a selective increase in D(2)(high) and/or D(3) in schizophrenia. It is possible that receptors with high affinity are not accessible by [(11)C]-(+)-PHNO because they are occupied by endogenous dopamine, a possibility that can be ruled out in future experiments.

Amisulpride's high and selective affinity for dopamine D2/3 (Ki 1.3/2.4 nM) receptors, lack of affinity for serotonin receptors, and its unusually high therapeutic doses (400-800 mg/day) makes it unique among atypical antipsychotics and prompted us to compare its actions with other antipsychotics in animal models.Amisulpride's effects on amphetamine and phencyclidine induced locomotor activity (AIL/PIL), conditioned avoidance response, catalepsy (CAT), subcortical Fos expression, and plasma prolactin was correlated to its time-course striatal D2/3 and prefrontal 5-HT2 receptor occupancy (D(2/3)/5-HT2RO); in comparison to haloperidol, clozapine, and risperidone.Unlike the atypicals clozapine and risperidone, amisulpride lacked 5-HT2RO and showed a 'delayed' pattern of D2/3RO: 43, 60 and 88% after 1, 2 and 6 h (100 mg/kg), respectively, despite a quick onset (1 h) and decline (6 h) of prolactin elevation. While haloperidol and risperidone were effective at D2RO60%, clozapine at D2/3RO50%, amisulpride was effective only when its D2RO exceeded 60% with a delayed latency and lasted longer than other antipsychotics. CAT was observed for haloperidol and risperidone when D2RO exceeded 80%, while in the case of amisulpride, CAT was not observed even when doses exceeded 90% D2/3RO. Amisulpride also displayed functional limbic selectivity in Fos expression like the other atypicals.Amisulpride's "delayed" functional profile on acute administration and the need for high doses is most likely due to its poor blood-brain-barrier penetration; however, it is distinct from other atypicals in showing low motor side-effects, activity against phencyclidine, and a mesolimbic preference, despite no action on serotonin receptors.

Objective Long-acting risperidone administered intramuscularly biweekly is approved for the management of schizophrenia. However, dosing of long-acting antipsychotics is frequently extended in clinical practice, and a recent clinical trial has lent support to monthly dosing of long-acting risperidone. The objective of this positron emission tomography (PET) study was to examine the striatal dopamine D(2) binding of long-acting risperidone administered intramuscularly once a month. Method Following at least 3 maintenance monthly injections of 50 mg long-acting risper-idone, 7 patients with a DSM-IV diagnosis of schizophrenia or schizoaffective disorder under-went PET using [(11)C]raclopride to measure D(2) binding potential within 4 days of the next scheduled injection. Data were collected from May to October 2003. This PET study was part of a larger 52-week clinical study wherein individuals received long-acting risperidone once monthly over a 1-year interval. One-year follow-up data were obtained from the 52-week parent investigation. Results The mean +/- SD D(2) receptor occupancy was 56% +/- 24% (range, 29%-82%). Of note, there were 4 subjects with less than 60% D(2) occupancy, none of whom relapsed over the course of the 1-year follow-up. The mean +/- SD total plasma level of risperidone plus 9-hydroxyrisperidone was 16.6 +/- 12.3 ng/mL (range, 5.7-40.8). Conclusion As with plasma levels, there was considerable variability in D(2) occupancy levels for individuals receiving long-acting risperidone. This work suggests a possibility that sustained D(2) occupancy at or above the accepted threshold with acute clinical response may not be necessary to maintain response, a hypothesis with important clinical implications as we consider antipsychotic dosing and future antipsychotic development. Trial registration clinicaltrials.gov Identifier: NCT00236353.

The D(2) receptors exist in either the high‐ or low‐affinity state with respect to agonists, and while agonists bind preferentially to the high‐affinity state, antagonists do not distinguish between the two states. [(11)C]‐(+)‐PHNO is a PET D(2) agonist radioligand and therefore provides a preferential measure of the D(2) (high) receptors. In contrast, [(11)C]raclopride is an antagonist radioligand and thus binds with equal affinity to the D(2) high‐ and low‐affinity states. The aim was to compare the brain uptake, distribution and binding characteristics between [(11)C]‐(+)‐PHNO and [(11)C]raclopride in volunteers using a within‐subject design. Both radioligands accumulated in brain areas rich in D(2)/D(3)‐receptors. However, [(11)C]‐(+)‐PHNO showed preferential uptake in the ventral striatum and globus pallidus, while [(11)C]raclopride showed preferential uptake in the dorsal striatum. Mean binding potentials were higher in the putamen (4.3 vs. 2.8) and caudate (3.4 vs 2.1) for [(11)C]raclopride, equal in the ventral‐striatum (3.4 vs. 3.3), and higher in the globus pallidus for [(11)C]‐(+)‐PHNO (1.8 vs. 3.3). Moreover [(11)C]‐(+)‐PHNO kinetics in the globus pallidus showed a slower washout than other regions. One explanation for the preferential binding of [(11)C]‐(+)‐PHNO in the globus pallidus and ventral‐striatum could be the presence of a greater proportion of high‐ vs. low‐affinity receptors in these areas. Alternatively, the observed distribution could also be explained by a preferential binding of D(3)‐over‐D(2) with [(11)C]‐(+)‐PHNO. This differential binding of agonist vs. antagonist radioligand, especially in the critically important region of the limbic striatum/pallidum, offers new avenues to investigate the role of the dopamine system in health and disease. Hum Brain Mapp 2008. © 2007 Wiley‐Liss, Inc.

Introduction In vitro, the dopamine D2 receptor exists in two states, with high and low affinity for agonists. The high-affinity state is the physiologically active state thought to be involved in dopaminergic illnesses such as schizophrenia. The positron emission tomography radiotracer [ 11 C](+)-PHNO ([ 11 C](+)-4-propyl-3,4,4 a ,5,6,10 b -hexahydro-2 H -naphtho[1,2- b ][1,4]oxazin-9-ol), being a D2 agonist, should selectively label the high-affinity state at tracer dose and therefore be more susceptible to competition by agonist as compared to the antagonist [ 3 H]raclopride, which binds to both affinity states. Methods We tested this prediction using ex vivo dual-radiotracer experiments in conscious rats. D2 antagonists (haloperidol or clozapine), a partial agonist (aripiprazole), a full agonist [(−)-NPA] or the dopamine-releasing drug amphetamine (AMPH) were administered to rats prior to an intravenous coinjection of [ 11 C](+)-PHNO and [ 3 H]raclopride. Rats were sacrificed 60 min after radiotracer injection. Striatum, cerebellum and plasma samples were counted for 11 C and 3 H. The specific binding ratio {SBR, i.e., [%ID/g (striatum)−%ID/g (cerebellum)]/(%ID/g (cerebellum)} was used as the outcome measure. Results In response to D2 antagonists, partial agonist or full agonist, [ 11 C](+)-PHNO and [ 3 H]raclopride SBRs responded indistinguishably in terms of both ED 50 and Hill slope (e.g., (−)-NPA ED 50 values are 0.027 and 0.023 mg/kg for [ 11 C](+)-PHNO and [ 3 H]raclopride, respectively). In response to AMPH challenge, [ 11 C](+)-PHNO and [ 3 H]raclopride SBRs were inhibited to the same degree. Conclusions We have shown that the SBRs of [ 11 C](+)-PHNO- and [ 3 H]raclopride do not differ in their response to agonist challenge. These results do not support predictions of the in vivo binding behavior of a D2 agonist radiotracer and cast some doubt on the in vivo applicability of the D2 two-state model, as described by in vitro binding experiments.

Objective The important role of serotonin-1A (5-hydroxytryptamine-1A [5-HT 1A ]) receptors in cognition, behavior, and drug response is increasingly being recognized. Postmortem studies suggest decreased 5-HT 1A receptors in patients with Alzheimer disease (AD), but this has not been confirmed in vivo. Our primary objective was to assess the extent of 5-HT 1A receptor losses in mild to moderate AD. Methods The authors examined 5-HT 1A receptors in 10 patients with mild to moderate AD and 10 healthy volunteers with the same sex and similar age using positron emission tomography imaging with the selective 5-HT 1A receptor radioligand, [ 11 C]WAY-100635. Regions of interest (ROIs) were manually drawn on coregistered magnetic resonance images for the frontal, lateral temporal, medial temporal (MTC), parietal, and cerebellar cortices. Using the simplified reference tissue model, 5-HT 1A binding potentials (BPs) were calculated relative to the cerebellum. Results After adjusting for partial volume effects, ROI analysis showed a significant group effect (AD versus comparison group) on BP. Analysis of between-subjects factors showed significantly decreased 5-HT 1A BP in the right MTC, but not in the other ROIs. Conclusion Given the strategic role of these receptors, loss of right medial temporal 5-HT 1A receptors might play an important role in AD symptomatology.

Although most patients treated for first-episode schizophrenia will experience considerable improvement with initial antipsychotic therapy, a subgroup experiences significant ongoing positive symptoms. Clozapine has unique efficacy in improving treatment-resistant patients with chronic schizophrenia, but its role in the treatment of first-episode patients remains unclear. A standardized treatment algorithm was implemented in our First Episode Psychosis Program, with patients receiving 2 trials with 2 second-generation antipsychotics (olanzapine, quetiapine, or risperidone at low, medium, and high doses), followed by a trial of clozapine as early as 25 weeks into the start of their treatment. Patients progress along the algorithm according to their response as defined by clinical rating scales. To date, 123 patients with first-episode schizophrenia have been treated according to the algorithm. Of these, 93 (76%) responded to the first trial of an antipsychotic. Only 7 (23%) of the remaining 30 patients responded to a second antipsychotic trial; 13 of the remaining 23 individuals agreed to a trial of clozapine. We compared the clozapine-treated group with a group of 9 patients who refused clozapine and chose to continue the same antipsychotic treatment as before. Subjects who received clozapine experienced a mean Brief Psychiatric Rating Scale change of 19 points (from 53.5 to 34.5) and a change in the Clinical Global Inventory severity rating from 5.4 to 3.5 (from severely ill to mildly ill); those who refused clozapine had a 2-point increase in mean Brief Psychiatric Rating Scale (from 53 to 55) and a 0.6-point increase in the mean Clinical Global Inventory severity rating from 5.4 to 6 (remaining markedly to severely ill). In clinical practice, there is a hesitancy to switch individuals to clozapine given its side effect profile and position as treatment of "last resort." The present findings suggest that clozapine may have an important role in the early treatment of first-episode patients whose psychosis does not remit with other second-generation antipsychotics during the first months of treatment.

It is hypothesized that due to an abnormal functioning of the reward system patients with schizophrenia form context-inappropriate associations. It has been shown that the dopamine target regions, especially the ventral striatum, are critical in the formation of reward associations. We wanted to examine how the ventral striatum responds as patients learn reward-related associations and how this neural response is linked to objective and subjective behavioral measures. Functional magnetic resonance imaging (fMRI) Blood oxygen level dependent (BOLD) responses were examined using aversive Pavlovian learning in 13 medicated patients with schizophrenia and 13 matched healthy controls. Colored circles served as conditioned stimulus (CS+) while a loud, individually adjusted, noise served as the unconditioned stimulus. Circles of another color served as neutral comparators (CS-). Subjective indices were assessed by a post-scan self-report, and galvanic skin responses (GSR) were used as objective measures of associative learning. fMRI data were analyzed using a random effects model in SPM2. Patients showed inappropriately strong activations in the ventral striatum in response to the neutral stimulus (CS-) as compared to the healthy controls. Consistent with this neural evidence of aberrant learning, patients also showed evidence of abnormal learning by self-report and as indexed by GSR. The main finding here is that patients with schizophrenia, when exposed to neutral stimuli in a threatening situation, show an abnormal pattern of learning. The aberrant activations and response are consistent with the idea that patients aberrantly assign motivational salience to neutral stimuli, and this process may be one of the aberrations that predisposes them to psychosis.

Predicting rewards and avoiding aversive conditions is essential for survival. Recent studies using computational models of reward prediction implicate the ventral striatum in appetitive rewards. Whether the same system mediates an organism's response to aversive conditions is unclear. We examined the question using fMRI blood oxygen level‐dependent measurements while healthy volunteers were conditioned using appetitive and aversive stimuli. The temporal difference learning algorithm was used to estimate reward prediction error. Activations in the ventral striatum were robustly correlated with prediction error, regardless of the valence of the stimuli, suggesting that the ventral striatum processes salience prediction error. In contrast, the orbitofrontal cortex and anterior insula coded for the differential valence of appetitive/aversive stimuli. Given its location at the interface of limbic and motor regions, the ventral striatum may be critical in learning about motivationally salient stimuli, regardless of valence, and using that information to bias selection of actions. Inc. Hum Brain Mapp, 2007. © 2006 Wiley‐Liss, Inc.

Repeated injections of amphetamine causes animals to become sensitized and supersensitive to DA. Previous work showed that the striata from such sensitized rats revealed a 3.5-fold increase in the density of D2(High) DA receptors, as measured by the guanine-nucleotide-sensitive component of [(3)H]raclopride binding. The present study was done to confirm these earlier findings by different methods and different ligands. The striata from amphetamine-sensitized rats showed an increase of 2.2-fold in the density of guanine-nucleotide-sensitive D2 receptors labeled by saturation experiments with [(3)H](+)PHNO. The proportion of D2(High) receptors was also found to increase 2.5-fold using the method of competition between DA and [(3)H]domperidone. The overall 2.2-3.5-fold increase of DA D2(High) receptors may explain why amphetamine-sensitized animals are much more sensitive to DA agonists, even though the total density of D2 receptors may apparently be unchanged or even decreased.

Objective While doctors often increase the dose of an antipsychotic when there is insufficient response, there is limited evidence that this intervention is any better than waiting longer on the lower dose. We put the proposition to test. Method In this 4-week, double-blind, randomized controlled trial conducted in psychiatric care from September 2012 to March 2015, 103 patients with schizophrenia (ICD-10) who did not respond to olanzapine 10 mg/d or risperidone 3 mg/d were randomly allocated to a dose-increment or -continuation group. In the increment group, antipsychotic doses were doubled for 4 weeks, whereas in the continuation group, doses were not changed. Completion rate (primary outcome measure); changes in psychopathology, function, and extrapyramidal symptoms; and response rate were compared between the groups. The relationship between baseline plasma antipsychotic concentrations and changes in psychopathology was examined. Results The completion rate was significantly lower in the increment group than in the continuation group (69.2% [36/52] vs 86.3% [44/51], P = .038). No significant superiority was observed in any of the outcome measures in the increment group compared to the continuation group, except the Positive and Negative Syndrome Scale (PANSS) positive subscale score change in intention-to-treat analysis. Those with lower plasma concentrations of olanzapine on their initial treatment showed a greater improvement on the PANSS positive subscale when their dose was increased (P = .042). Conclusions As a general strategy, patients with schizophrenia failing to respond to moderate antipsychotic doses may not benefit from an increase in dose. The possibility of benefit in those whose plasma antipsychotic concentrations at baseline are still low cannot be ruled out. Trial registration UMIN.ac.jp/ctr/index.htm identifier: UMIN000008667.