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Background: We reviewed systematically the results of genetic studies investigating associations between putative susceptibility genes for attention-deficit hyperactivity disorder (ADHD) and neuropsychological traits relevant for this disorder. Methods: We identified papers for review through the PubMed database. Results: Twenty-nine studies examined 10 genes (DRD4, DAT1, COMT, DBH, MAOA, DRD5, ADRA2A, GRIN2A, BDNF and TPH2) in relation to neuropsychological traits relevant for ADHD. For DRD4, the continuous performance test (CPT) and derived tasks were the most used tests. Association of high reaction time variability with the 7-repeat allele absence appears to be the most consistent result and seems to be specific to ADHD. Speed of processing, set-shifting and cognitive impulsiveness were less frequently investigated but seem to be altered in the 7-repeat allele carriers. No effect of genotype was found on response inhibition (the stop and go/no-go tasks). For DAT1, 4 studies provide conflicting results in relation to omission and commission errors from CPT and derived tasks. High reaction time variability seems to be the most replicated cognitive marker associated with the 10-repeat homozygosity. The other genes have attracted fewer studies, and the reported findings need to be replicated. Limitations: Although we aimed to perform a formal meta-analysis, this was not possible because the number of studies using the same neurocognitive endophenotypes was limited. We referred only minimally to the various theoretical frameworks in this field of research; more detail would have been beyond the scope of our systematic review. Finally, sample sizes in most of the studies we reviewed were small. Thus, some negative findings could be attributed to a lack of statistical power, and positive results should be considered preliminary until they are replicated in extended samples. Conclusion: Several methodological issues, including measurement errors, developmental changes in cognitive abilities, sex, psychostimulant effects and presence of comorbid conditions, represent confounding factors and may explain conflicting results. [ABSTRACT FROM AUTHOR]

BACKGROUND: Low-function alleles of the serotonin transporter promoter polymorphism (5HTTLPR) have been linked to various psychopathological entities, especially in individuals exposed to prior stressors. In women with bulimic syndromes, we explored associations with personality pathology of 5HTTLPR and prior sexual or physical maltreatment. METHODS: Ninety-two women with bulimic syndromes were genotyped for 5HTTLPR short (S) and long (L(G) and L(A)) alleles and were then assessed for eating symptoms, dimensional personality disturbances, history of sexual or physical abuse and borderline personality disorder (BPD). RESULTS: With a classification based on a biallelic model of 5HTTLPR (i.e., presence or absence of at least 1 S-allele copy), multiple regression analyses indicated significant proportions of variance in stimulus seeking and insecure attachment to be explained by abuse x genotype interaction effects, with greater psychopathology always occurring in S-allele carriers who had been abused. Likewise, a logistic regression analysis linked BPD to significant main effects of genotype and abuse. Analyses that aggregated carriers according to a triallelic model of 5HTTLPR (i.e., presence or absence of at least 1 copy of a presumably low-function S or LG allele) produced similar patterns but no statistically significant effects. CONCLUSIONS: Traits such as sensation seeking and insecure attachment are, on average, elevated in 5HTTLPR S-allele carriers with bulimic syndromes who report prior physical or sexual maltreatment. These results add to the literature associating pronounced psychopathological manifestations, with conjoint effects of stress and the 5HTTLPR polymorphism. [ABSTRACT FROM AUTHOR]

OBJECTIVE: To determine whether children with attention-deficit hyperactivity disorder (ADHD) and learning disabilities respond differently to methylphenidate (MPH) compared with children with ADHD only. METHODS: We conducted a prospective, double-blind, placebo-controlled, randomized, 2-week crossover trial of MPH, during which response to MPH was assessed. Learning ability was appraised using the Wide Range Achievement Test, Revised (WRAT-R), for English-speaking students and the Test de rendement pour francophones for French-speaking students. The study was conducted at the Douglas Hospital, a McGill University-affiliated teaching hospital in Montréal. Ninety-five children, aged 6-12 years, who met the Diagnostic and Statistical Manual of Mental Disorders, fourth edition (DSM-IV), criteria for ADHD participated in the study, which ran from 2001 to 2004. The outcome measure used was the Consensus Clinical Response, an indicator of the degree of clinical improvement shown when taking MPH. RESULTS: The proportion of children with learning disabilities who responded to MPH (55%) was significantly smaller (chi(2)1 = 4.5, p = 0.034) than the proportion of children without learning disabilities who responded adequately to MPH (75%). This difference was mainly because of children with mathematics disability being particularly unresponsive to MPH (chi(2)1 = 4.5, p = 0.034). Children with reading disability did not show this pattern of poor response (chi(2)1 = 1.0, p = 0.33). CONCLUSION: Children with ADHD and comorbid learning disability tended to respond more poorly to MPH. In particular, children with disability in mathematics responded less to MPH than those without disability in mathematics. Additional therapy may be indicated for this group of patients. [ABSTRACT FROM AUTHOR]

This paper describes a research program intended to provide a better understanding of the influence of several putative risk factors for schizophrenia on child development and psychosis. Two related components of the overall program are described: the retrospective EnviroGen projects, which use a variety of putative risk factors to explain variance in several dimensions of schizophrenia and in psychotic symptoms in community controls, and Project Ice Storm, which prospectively examines the effects of prenatal maternal stress in the children of women who were exposed to the 1998 Quebec ice storm during their pregnancies. The EnviroGen projects have been successful in explaining variance in several dimensions of illness, including premorbid adjustment and severity of dissociative symptoms. Project Ice Storm has demonstrated the noxious effects of prenatal stress on cognitive and language development in children. We have also found that 'ice storm children' exposed in specific weeks of gestation show greater dermatoglyphic asymmetry, as has been reported for samples of patients with schizophrenia. In both studies, prenatal maternal stress has been associated with more severe childhood behaviour problems. The combination of retrospective and prospective studies is a rich source of triangulated results providing information about developmental psychopathology. [ABSTRACT FROM AUTHOR]

OBJECTIVES: Genetic and nonshared environmental factors (experienced by 1 family member to the exclusion of the others) have been strongly implicated in the causes of attention-deficit hyperactivity disorder (ADHD). Pregnancy, labour/delivery and neonatal complications (PLDNC) have often been associated with ADHD; however, no investigations aimed at delineating the shared or nonshared nature of these factors have been reported. We aimed to identify those elements of the PLDNC that are more likely to be of a nonshared nature. METHODS: We used an intrafamily study design, comparing the history of PLDNC between children diagnosed with ADHD, according to the criteria of the Diagnostic and Statistical Manual of Mental Disorders, fourth edition (DSM-IV), and their unaffected siblings. Children with ADHD were recruited from the outpatient, day-treatment program of the Child Psychiatry Department, Douglas Hospital, Montreal. The unaffected sibling closest in age to the child with ADHD was used as a control. The history of PLDNC was assessed using the Kinney Medical and Gynecological Questionnaire and the McNeil-Sjostrom Scale for both children with ADHD and their siblings. Seventy children with ADHD along with 50 of their unaffected siblings agreed to participate in the study. Child Behavior Checklist (CBCL), Continuous Performance Test (CPT) and Restricted Academic Situation Scale (RASS) scores were also used as measures of ADHD symptoms in children with ADHD. RESULTS: The children with ADHD had significantly higher rates of neonatal complications compared with their unaffected siblings (F4,196 = 3.67, p < 0.006). Furthermore, neonatal complications in the children with ADHD were associated with worse CBCL total and externalizing scores and with poorer performance on the CPT. CONCLUSIONS: These results suggest that neonatal complications are probably a nonshared environmental risk factor that may be pathogenic in children with ADHD. [ABSTRACT FROM AUTHOR]

OBJECTIVE: To review the results of genetic studies investigating dopamine-related genes in attention-deficit hyperactivity disorder (ADHD). DATA SOURCES: Papers (association/linkage, meta-analyses and animal model studies) were identified through searches of the PubMed database and systematically reviewed. DATA SYNTHESIS: Consistent results from molecular genetic studies are pointing strongly to the possible link between 2 specific genes, the dopamine transporter (SLC3A6) and the dopamine receptor 4 (DRD4), and ADHD. CONCLUSIONS: The implication of SLC6A3 and DRD4 genes in ADHD appears to be one of the most replicated in psychiatric genetics and strongly suggests the involvement of the brain dopamine systems in the pathogenesis of ADHD. However, more work is required to further these findings by genotype-to-phenotype correlations and identify the functional allelic variants/mutations that are responsible for these associations. The role of other dopamine genes, which may have smaller effects than SLC6A3 and DRD4, needs also to be determined. [ABSTRACT FROM AUTHOR]

The schizophrenia phenotype is heterogeneous with respect to clinical presentation, long-term response to medication, and outcome, possibly reflecting genetic heterogeneity and/or the presence of modifier genes. Compared to non-responders, schizophrenic patients who are responders to neuroleptic medications are characterized by a high female/male ratio, a better longterm outcome and more frequently disturbed dopamine neurotransmission. In this study, we compared two groups of schizophrenic patients selected on the basis of their long-term response to neuroleptics (excellent responders and non-responders) and a group of healthy volunteers, with regard to a missense mutation (677C→T) in the methylenetetrahydrofolate reductase (MTHFR) gene. This polymorphism was chosen because it is functional5 and was previously associated with schizophrenia. The present study revealed a significant association between schizophrenia and allele T of this gene. This association was entirely due to an over-representation of allele T in responder patients compared to controls; nonresponder patients did not differ from controls. Genotype TT was more frequent in responder patients compared to controls, thus replicating the findings of Arinami et al. These results strongly suggest that the MTHFR gene is involved in the pathogenesis of schizophrenia characterized by a rapid and sustained therapeutic response to typical neuroleptics and/or a good long-term prognosis/favorable therapeutic outcome. [ABSTRACT FROM AUTHOR]

Several studies have indicated that patients with bipolar disorder (BD) who respond well to lithium prophylaxis constitute a biologically distinct subgroup. Lithium is thought to stablize mood by acting at the phosphoinositide cycle. We have investigated a polymorphism located in the gene (PLCG1) that codes for a γ-1 isozyme of phospholipase (PLC), an enzyme that plays an important role in the phosphoinositide second messenger system. A population-based association study and a family-based linkage study were carried out on patients who were considered excellent responders to lithium prophylaxis. Response to lithium was evaluated prospectively with an average follow-up of 14.4 ± 6.8 years. The PLCG1 polymorphism was investigated in 136 excellent lithium responders and 163 controls. In addition, the segregation of this marker was studied in 32 families ascertained through lithium-responsive bipolar probands. The allele distributions between lithium-responsive bipolar patients and controls were different, with a higher frequency of one of the PLCG1 polymorphisms in patients (χ² = 8.09; empirical P=0.033). This polymorphism, however, confers only a small risk (OR = 1.88, CI 1.19-3.00). Linkage studies with the same marker yielded modest support for the involvement of this gene in the pathogenesis of BD when unilineal families were considered (Max LOD=1.45; empirical P=0.004), but not in the whole sample. Our results provide preliminary evidence that a PLC isozyme may confer susceptibility to bipolar disorder, probably accounting for a fraction of the total genetic variance. Whether this polymorphism is impli- cated in the pathogenesis of BD or in the mechanism of lithium response remains to be determined. [ABSTRACT FROM AUTHOR]

Pharmacological, genetic and expression studies implicate N-methyl-D-aspartate (NMDA) receptor hypofunction in schizophrenia (SCZ). Similarly, several lines of evidence suggest that autism spectrum disorders (ASD) could be due to an imbalance between excitatory and inhibitory neurotransmission. As part of a project aimed at exploring rare and/or de novo mutations in neurodevelopmental disorders, we have sequenced the seven genes encoding for NMDA receptor subunits (NMDARs) in a large cohort of individuals affected with SCZ or ASD (n=429 and 428, respectively), parents of these subjects and controls (n=568). Here, we identified two de novo mutations in patients with sporadic SCZ in GRIN2A and one de novo mutation in GRIN2B in a patient with ASD. Truncating mutations in GRIN2C, GRIN3A and GRIN3B were identified in both subjects and controls, but no truncating mutations were found in the GRIN1, GRIN2A, GRIN2B and GRIN2D genes, both in patients and controls, suggesting that these subunits are critical for neurodevelopment. The present results support the hypothesis that rare de novo mutations in GRIN2A or GRIN2B can be associated with cases of sporadic SCZ or ASD, just as it has recently been described for the related neurodevelopmental disease intellectual disability. The influence of genetic variants appears different, depending on NMDAR subunits. Functional compensation could occur to counteract the loss of one allele in GRIN2C and GRIN3 family genes, whereas GRIN1, GRIN2A, GRIN2B and GRIN2D appear instrumental to normal brain development and function.

Background: Schizophrenia spectrum and other psychotic disorders (SSPD) are among the most debilitating of all mental disorders. While the evidence for psychosocial interventions such as cognitive behavioral therapy and peer support has significantly improved, access to these services remains limited. This paper describes a protocol for a pragmatic feasibility study of a digital mental health intervention (HoryzonsCa) that provides access to evidence-based psychosocial interventions, social networking, and clinical and peer support services through a secured, web-based platform for adults diagnosed with SSPD., Objective: The objectives are: (1) Adapt and translate HoryzonsCa for implementation in English and French; (2) Develop an implementation and training strategy; (3) Assess the acceptability, safety, and demand of HoryzonsCa; (4) Assess clinical outcomes and perceived impacts; (5) Examine the experiences and process of adapting and implementing HoryzonsCa; (6) Explore the role of sociocultural and demographic factors on HoryzonsCa outcomes and implementation., Methods: This feasibility study will use a single-group, pre-post, mixed-methods (QUAN-QUAL convergent) research design, with assessments at baseline and 12 weeks. The study aims to recruit 100 individuals (ages 18-50) diagnosed with SSPD from two healthcare settings in Canada. Data collection includes interview-based psychometric measures, self-reports, focus groups, and interviews with participants. The study will also collect qualitative data from moderators and the research team, and will be conducted entirely remotely., Conclusions: This study has been prospectively registered and is underway. It will provide timely information on the feasibility and potential impacts of using digital mental health services for individuals with chronic mental health conditions., Trial Registration: ISRCTN12561259; https://doi.org/10.1186/ISRCTN12561259 (250/max 250 words)., Competing Interests: Shalini Lal reports a research grant from Hoffman-La Roche, partially supporting this Phase 3 study on the implementation and evaluation of HoryzonsCa; Mario Alvarez-Jimenez, John F. Gleeson, and Ridha Joober are coinvestigators on this grant. Ridha Joober served as speaker and member of advisory board committees for Pfizer, Janssen, Bristol Myers Squibb, Sunovian, Myelin and Associates, Otsuka, Lundbeck, Shire, and Perdue. He also received grants from Janssen, Bristol Myers Squibb, Otsuka, Lundbeck, Astra Zeneca, and HLS Therapeutics Inc. All of these are unrelated to this study. Martin Lepage reports grants from Otsuka Lundbeck Alliance, diaMentis, Roche, personal fees from Otsuka Canada, personal fees from Lundbeck Canada, grants and personal fees from Janssen, and personal fees from Boehringer-Ingelheim outside the submitted work. Martin Lepage also reports a grant from Hoffman-La Roche (partially supporting this Phase 3 study on implementing and evaluating HoryzonsCa). All other authors declare no financial or nonfinancial competing interests., (© The Author(s) 2024.)

Background: Cognitive symptoms, among the core symptoms of schizophrenia, are associated with poor functional outcome and burden of illness. To date, there is no effective pharmacological treatment for these symptom clusters. Augmentation with psychostimulants has been proposed as a potential treatment option., Objectives: The present study aims to assess off-label use of adjunctive methylphenidate extended release (ER) in patients with schizophrenia who are stable on antipsychotic medications, and to assess its efficacy on functioning and cognitive outcome., Methods: This is a single centre study at the Royal Ottawa Mental Health Centre. An open-label fixed dose controlled cross-over trial is planned. Eligible participants will be randomized into one of two arms of the study: 1) four weeks of add-on methylphenidate ER 36 mg, or 2) four weeks of treatment as usual. At 4 weeks, participants will switch arms. The duration of the study includes 8 weeks of treatment and a follow-up visit at 12 weeks. Primary outcome measures include tablet-based tests of functioning and cognition (VRFCAT and BAC) and will be administered at baseline and every 4 weeks. We are aiming to recruit a total of 24 participants., Expected Outcomes: The proposed project intends to assess a potential treatment option for cognitive deficits of schizophrenia, for which there are no recommendations by current treatment guidelines. The novelty and significance of the current study is that it investigates this intervention and assess applicability of it in a "real world setting" in a tertiary care hospital., Competing Interests: The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Dr. Harvey has received consulting fees or travel reimbursements from Alkermes, Bio Excel, Boehringer Ingelheim, Karuna Pharma, Merck Pharma, Minerva Pharma, and WCG Endpoint Solutions during the past year. He receives royalties from the Brief Assessment of Cognition in Schizophrenia (Owned by WCG, Inc. and contained in the MCCB). He is chief scientific officer of i-Function, Inc. Other authors have no conflict of interest to declare., (© 2024 The Authors.)

Competing Interests: Competing interests:: Lena Palaniyappan has received research support from the Monique H. Bourgeois Chair in Developmental Disorders; grants from the Graham Boeckh Foundation (Douglas Research Centre, McGill University) and the Canadian Institutes of Health Research; royalties from Oxford University Press and SPMM Course, UK; and speaker’s honoraria from Janssen Canada and Otsuka Canada. He reports a salary award from the Fonds de recherche du Québec-Santé. He is a member of the editorial board of the Canadian Journal of Psychiatry. He is the coeditor in chief of JPN; he had no role in editorial decision-making for this article. No other competing interests were declared.

There is widespread overlap across major psychiatric disorders, and this is the case at different levels of observations, from genetic variants to brain structures and function and to symptoms. However, it remains unknown to what extent these commonalities at different levels of observation map onto each other. Here, we systematically review and compare the degree of similarity between psychiatric disorders at all available levels of observation. We searched PubMed and EMBASE between January 1, 2009 and September 8, 2022. We included original studies comparing at least four of the following five diagnostic groups: Schizophrenia, Bipolar Disorder, Major Depressive Disorder, Autism Spectrum Disorder, and Attention Deficit Hyperactivity Disorder, with measures of similarities between all disorder pairs. Data extraction and synthesis were performed by two independent researchers, following the PRISMA guidelines. As main outcome measure, we assessed the Pearson correlation measuring the degree of similarity across disorders pairs between studies and biological levels of observation. We identified 2975 studies, of which 28 were eligible for analysis, featuring similarity measures based on single-nucleotide polymorphisms, gene-based analyses, gene expression, structural and functional connectivity neuroimaging measures. The majority of correlations (88.6%) across disorders between studies, within and between levels of observation, were positive. To identify a consensus ranking of similarities between disorders, we performed a principal component analysis. Its first dimension explained 51.4% (95% CI: 43.2, 65.4) of the variance in disorder similarities across studies and levels of observation. Based on levels of genetic correlation, we estimated the probability of another psychiatric diagnosis in first-degree relatives and showed that they were systematically lower than those observed in population studies. Our findings highlight that genetic and brain factors may underlie a large proportion, but not all of the diagnostic overlaps observed in the clinic., (© 2024. The Author(s).)

Background: Cognitive impairment are among the core features of schizophrenia, experienced by up to 75% of patients. Available treatment options for schizophrenia including dopamine antagonists and traditional antipsychotic medications have not been shown to confer significant benefits on cognitive deficits. Contrary to the focus on management of positive symptoms in schizophrenia, cognitive abilities are main predictor of independent living skills, functional abilities, employment, engagement in relapse prevention, and patients' subjective sense of well-being and quality of life. This review aims to provide a summary of recent literature on pharmacological options for the treatment of cognitive deficits in schizophrenia., Methods: We conducted a literature search of studies from 2011 to 2021 across four electronic databases including PubMed, PsycInfo, MEDLINE, and Embase. Human studies using a pharmacological treatment for cognitive impairment in schizophrenia were included., Results: Fifty-eight eligible publications, representing 11 pharmacological classes, were included in this review. Major limitations involved small sample size, methodological limitations as well as heterogeneity of participants and outcome measures., Conclusions: Overall evidence remains inconclusive for any pharmacological classes studied for the treatment of cognitive deficits in schizophrenia. Methodological limitations in a majority of the studies rendered their findings preliminary. We further discuss possible explanations for these findings that could guide future research., (© 2023 The Authors. Neuropsychopharmacology Reports published by John Wiley & Sons Australia, Ltd on behalf of The Japanese Society of Neuropsychopharmacology.)