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The placebo response is a vexing problem for clinical trial design and drug development. Defined as a clinical improvement that occurs in participants treated with a physiologically inert substance, the placebo response has been largely ascribed to “expectation of clinical improvement and Pavlovian conditioning.”1 Other factors certainly play a role, however, including strict application of inclusion and exclusion criteria at study entry with subsequent reversion to the mean; that is, participants and investigators, knowing entry criteria for a trial, may subconsciously (or intentionally) overrate signs and symptoms to get into a trial, and then present at subsequent visits in their more typical state. Though this is not traditionally considered part of the true placebo response, it is likely that this phenomenon contributes to what is measured as the magnitude of the placebo response. Clinical trial design strategies such as central blinded ratings and avoiding the use of primary outcome measure criteria for screening can mitigate this phenomenon, but these are not routinely utilized.

To determine whether the Parkinson disease-related covariance pattern (PDRP) expression is abnormally increased in idiopathic REM sleep behavior disorder (RBD) and whether increased baseline activity is associated with greater individual risk of subsequent phenoconversion.For this cohort study, we recruited 2 groups of RBD and control subjects. Cohort 1 comprised 10 subjects with RBD (63.5 ± 9.4 years old) and 10 healthy volunteers (62.7 ± 8.6 years old) who underwent resting-state metabolic brain imaging with (18)F-fluorodeoxyglucose PET. Cohort 2 comprised 17 subjects with RBD (68.9 ± 4.8 years old) and 17 healthy volunteers (66.6 ± 6.0 years old) who underwent resting brain perfusion imaging with ethylcysteinate dimer SPECT. The latter group was followed clinically for 4.6 ± 2.5 years by investigators blinded to the imaging results. PDRP expression was measured in both RBD groups and compared with corresponding control values.PDRP expression was elevated in both groups of subjects with RBD (cohort 1: p0.04; cohort 2: p0.005). Of the 17 subjects with long-term follow-up, 8 were diagnosed with Parkinson disease or dementia with Lewy bodies; the others did not phenoconvert. For individual subjects with RBD, final phenoconversion status was predicted using a logistical regression model based on PDRP expression and subject age at the time of imaging (r(2) = 0.64, p0.0001).Latent network abnormalities in subjects with idiopathic RBD are associated with a greater likelihood of subsequent phenoconversion to a progressive neurodegenerative syndrome.

Objective: Subtle signs and symptoms of Huntington disease (HD) are often present before impairments reach a point where the neurologic disease is manifest and a diagnosis must be considered. The objective is to examine the prognostic significance of these early clinical signs and symptoms regarding time until unequivocal clinical HD diagnosis. Methods: We analyzed longitudinal data from 218 at-risk but healthy participants in the Huntington Study Group database who had either normal motor examination results or minimal soft motor signs at first observation. This group was followed periodically in HD clinics for up to 4.5 years. We used survival analysis to examine predictors of time until HD diagnosis. Results: Diagnostic prediction was significantly improved using specific, nonredundant items from the Unified Huntington9s Disease Rating Scale. When a movement disorder specialist initially had a global impression of “soft signs” present, cumulative relative risk of diagnosis was 4.68 times greater at 1.5 years of follow-up and 3.58 at 3 years. A neuropsychological test pattern with psychomotor speed 1 SD worse than a semantic knowledge measure increased cumulative risk by 1.99 times at 1.5 years and 1.81 at 3 years. Finally, reports of various subjective HD symptoms increased 3-year relative risk by 2.6 to 3.4. Conclusions: Findings demonstrate that neuropsychological performance and both the clinician rating and the patient subjective perception of motor difficulties contribute nonredundantly to a prediction of Huntington disease diagnosis. These findings may have implications for prognostic assessment of persons at risk and eventually assist with early interventions.

Objective: To determine if future studies of coenzyme Q10 and GPI-1485 in Parkinson disease (PD) may be warranted. Methods: We conducted a randomized, double-blind, calibrated futility clinical trial of coenzyme Q10 and GPI-1485 in early untreated PD using placebo data from the DATATOP study to establish the futility threshold. Results: The primary outcome measure (change in total Unified Parkinson's Disease Rating Scale scores over 1 year) did not meet the prespecified criteria for futility for either agent. Secondary analyses using calibration controls and other more recent placebo data question the appropriateness of the predetermined definition of futility, and suggest that a more restrictive threshold may be needed. Conclusions: Coenzyme Q10 and GPI-1485 may warrant further study in Parkinson disease, although the data are inconsistent. Additional factors (cost, availability of other agents, more recent data on placebo outcomes, other ongoing trials) should also be considered in the selection of agents for Phase III studies. NEUROLOGY 2007;68:20-28

Background: Although the pathophysiology remains unknown, most nondemented patients with PD have difficulty with frontal tasks, including trial-and-error sequence learning. If given time, they can perform cognitive tasks of moderate difficulty as well as controls. However, it is not known how brain function is altered during this time period to preserve higher cortical function in the face of PD pathology.Method: To evaluate this phenomenon, the authors matched sequence learning between PD and control subjects for the last 30 seconds of a PET scan. Learning during the initial 50 seconds of PET was unconstrained.Results: Learning indices were equivalent between groups during the last 30 seconds of the scan, whereas rates of acquisition, correct movements, and forgetting differed in the first 30 seconds. In normal controls sequence learning was associated with activations in the right prefrontal, premotor, parietal, rostral supplementary motor area, and precuneus regions. To achieve equal performance, the PD group activated greater volume within these same regions, and also their left sided cortical homologs and the lateral cerebellum bilaterally.Conclusions: Mildly affected patients with PD demonstrated only modest impairment of learning during the first 30 seconds of the task and performed equivalently with controls thereafter. However, the mechanism by which they achieved equiperformance involved considerable changes in brain function. The PD group had to activate four times as much neural tissue as the controls, including recruiting brain from homologous cortical regions and bilateral lateral cerebellum.

To assess the effects of levodopa on resting-state brain metabolism in PD.In previous studies the authors used [18F] fluorodeoxyglucose (FDG) and PET to quantify regional metabolic abnormalities in PD. They found that this disease is characterized reproducibly by a specific abnormal PD-related pattern (PDRP). In this study the authors used IV levodopa infusion to quantify the effects of dopamine replacement on regional metabolism and PDRP network activity. They tested the hypothesis that clinical response to dopaminergic therapy correlates with these metabolic changes.The authors used FDG/PET to measure resting-state regional brain metabolism in seven patients with PD (age, 59.4 +/- 4.2 years; Hoehn and Yahr stage, 1.9 +/- 0.7, mean +/- SD); subjects were scanned both off levodopa and during an individually titrated constant-rate IV levodopa infusion. The authors used statistical parametric mapping to identify significant changes in regional brain metabolism that occurred with this intervention. They also quantified levodopa-induced changes in PDRP expression. Metabolic changes with levodopa correlated with clinical improvement as measured by changes in Unified PD Rating Scale (UPDRS) motor scores.Levodopa infusion improved UPDRS motor ratings (30.6% +/- 12.0%, p0.002) and significantly decreased regional glucose metabolism in the left putamen, right thalamus, bilateral cerebellum, and left primary motor cortex (p0.001). Changes in pallidal metabolism correlated significantly with clinical improvement in UPDRS motor ratings (p0.01). Levodopa infusion also resulted in a significant (p = 0.01) decline in PDRP expression. The changes in PDRP activity mediated by levodopa correlated significantly with clinical improvement in UPDRS motor ratings (r = -0.78, p0.04).Levodopa reduces brain metabolism in the putamen, thalamus, and cerebellum in patients with PD. Additionally, levodopa reduces PD-related pattern activity, and the degree of network suppression correlates with clinical improvement. The response to dopaminergic therapy in Patients with PD may be determined by the modulation of cortico-striato-pallido-thalamocortical pathways.

Background Preclinical studies suggest that glutamate antagonists help ameliorate motor fluctuations in patients with PD treated with levodopa. Methods In a multicenter, randomized, double-blind, placebo-controlled, parallel-group, dose-ranging study, the authors assessed the safety, tolerability, and efficacy of the glutamate receptor blocker remacemide hydrochloride in 279 patients with motor fluctuations treated with levodopa. The primary objective was to assess the short-term tolerability and safety of four dosage levels of remacemide during 7 weeks of treatment. Patients were also monitored with home diaries and the Unified PD Rating Scale (UPDRS) to collect preliminary data on treatment efficacy. Results Remacemide was well tolerated up to a dosage of 300 mg/d on a twice daily schedule and 600 mg/d on a four times daily schedule. The most common dosage-related adverse events were dizziness and nausea, as observed in previous studies of remacemide. The percent "on" time and motor UPDRS scores showed trends toward improvement in the patients treated with 150 and 300 mg/d remacemide compared with placebo-treated patients, although these improvements were not significant. Conclusion Remacemide is a safe and tolerable adjunct to dopaminergic therapy for patients with PD and motor fluctuations. Although this study had limited power to detect therapeutic effects, the observed improvement is consistent with studies of non-human primates with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced parkinsonian signs and symptoms. Additional studies are warranted to confirm these results over an extended period of observation, and to explore the potential neuroprotective effects of remacemide in slowing the progression of PD.

We conducted a double-blind placebo-controlled crossover study to assess the efficacy of deprenyl for attention deficit hyperactivity disorder (ADHD) in children and adolescents with comorbid Tourette9s syndrome (TS). Twenty-four subjects (21 boys, 3 girls; mean age 12 years) were enrolled at two sites (University of Rochester and Baylor College of Medicine). The design included two 8-week treatment periods separated by a 6-week washout period. The primary outcome measures for ADHD and tic severity were total scores on the DuPaul Attention Deficit Hyperactivity Scale (DADHS) and the Yale Global Tic Severity Scale (YGTSS). Fifteen subjects completed the study. The primary analysis revealed no statistically significant beneficial effect of deprenyl on the DADHS (mean improvement 1.3; 95% CI, minus 2.7 to 5.3; p equals 0.50). Further post-hoc analyses revealed, however, that the effect of deprenyl in the first period was substantial (p equals 0.02). There was a marginally statistically significant beneficial effect of deprenyl on the YGTSS total score (p equals 0.06). Deprenyl may improve both ADHD and tics in children with TS and warrants further study. NEUROLOGY 1996;46: 965-968.

To identify metabolic brain networks that are associated with Tourette syndrome (TS) and comorbid obsessive-compulsive disorder (OCD).We utilized [(18)F]-fluorodeoxyglucose and PET imaging to examine brain metabolism in 12 unmedicated patients with TS and 12 age-matched controls. We utilized a spatial covariance analysis to identify 2 disease-related metabolic brain networks, one associated with TS in general (distinguishing TS subjects from controls), and another correlating with OCD severity (within the TS group alone).Analysis of the combined group of patients with TS and healthy subjects revealed an abnormal spatial covariance pattern that completely separated patients from controls (p0.0001). This TS-related pattern (TSRP) was characterized by reduced resting metabolic activity of the striatum and orbitofrontal cortex associated with relative increases in premotor cortex and cerebellum. Analysis of the TS cohort alone revealed the presence of a second metabolic pattern that correlated with OCD in these patients. This OCD-related pattern (OCDRP) was characterized by reduced activity of the anterior cingulate and dorsolateral prefrontal cortical regions associated with relative increases in primary motor cortex and precuneus. Subject expression of OCDRP correlated with the severity of this symptom (r = 0.79, p0.005).These findings suggest that the different clinical manifestations of TS are associated with the expression of 2 distinct abnormal metabolic brain networks. These, and potentially other disease-related spatial covariance patterns, may prove useful as biomarkers for assessing responses to new therapies for TS and related comorbidities.

In a randomized, double-blind, placebo-controlled study in 64 subjects with Huntington disease (HD), 8 g/day of creatine administered for 16 weeks was well tolerated and safe. Serum and brain creatine concentrations increased in the creatine-treated group and returned to baseline after washout. Serum 8-hydroxy-2'-deoxyguanosine (8OH2'dG) levels, an indicator of oxidative injury to DNA, were markedly elevated in HD and reduced by creatine treatment.

Dopaminergic therapy with levodopa improves motor function in PD patients, but the effects of levodopa on cognition in PD remain uncertain.To use H(2)(15)O and PET to assess the effect of levodopa infusion on motor sequence learning in PD.Seven right-handed PD patients were scanned "on" and "off" levodopa while performing a sequence learning task. The changes in learning performance and regional brain activation that occurred during this intervention were assessed.During PET imaging, levodopa infusion reduced learning performance as measured by subject report (p0.05). This behavioral change was accompanied by enhanced activation during treatment in the right premotor cortex and a decline in the ipsilateral occipital association area (p0.01). Levodopa-induced changes in learning-related activation responses in the occipital association cortex correlated with changes in learning indexes (p0.01).Levodopa treatment appears to have subtle detrimental effects on cognitive function in nondemented PD patients. These effects may be mediated through an impairment in brain activation in occipital association cortex.

To determine whether motor, behavioral, or psychiatric symptoms in Huntington disease (HD) predict skilled nursing facility (SNF) placement.Subjects were participants in the Huntington Study Group's Unified Huntington Disease Rating Scale Database (Rochester, NY) between January 1994 and September 1999. Specific motor, psychiatric, and behavioral variables in subjects residing at home and in SNF were analyzed using chi2 and Student's t-tests. For a subset of subjects for whom longitudinal data existed, a Cox proportional hazards model controlling for age, sex, and disease duration was used.Among 4,809 subjects enrolled, 3,070 had clinically definite HD. Of these, 228 (7.4%) resided in SNF. The SNF residents' average age was 52 years, average disease duration was 8.6 years, and they were predominantly women (63%). The SNF residents had worse motor function (chorea, bradykinesia, gait abnormality, and imbalance, p0.0001); were more likely to have obsessions, compulsions, delusions, and auditory hallucinations; and had more aggressive, disruptive (p0.0001), and irritable behaviors (p = 0.0012). For 1,559 subjects, longitudinal data existed (average length of follow-up, 1.9 years), and 87 (5%) moved from home to SNF. In the Cox model, bradykinesia (HR 1.965, 95% CI 1.083 to 3.564), impaired gait (HR 3.004, 95% CI 1.353 to 6.668), and impaired tandem walking (HR 2.546, 95% CI 1.460 to 4.439) were predictive of SNF placement.Institutionalized patients with HD are more motorically, psychiatrically, and behaviorally impaired than their counterparts living at home. However, motor variables alone predicted institutionalization. Treatment strategies that delay the progression of motor dysfunction in HD may postpone the need for institutionalization.

Restless legs syndrome (RLS) is characterized by diurnal restless discomfort, usually affecting the lower extremities, often associated with periodic limb movements in sleep. It is among the most prevalent neurologic syndromes and yet remains a puzzle in many respects; even its prevalence has been a matter of debate, with estimates ranging from 1 to 20%.1,2 RLS may be classified as primary or secondary with secondary causes including myelopathy, uremia, iron deficiency, and Parkinson disease. Peripheral neuropathy has been cited as a potential cause of RLS, though this association has been controversial, with prevalence estimates of RLS in patients with peripheral neuropathy ranging from 5 to 54%. In the current issue of Neurology® , Hattan et al.3 report the results of a prospective, case-control study examining the prevalence of RLS …

The functional brain networks underlying the clinical manifestations of Gilles de la Tourette's syndrome (TS) are currently unknown. To identify these networks, we studied TS patients and normal subjects with 18F-fluorodeoxyglucose (FDG) and PET employing a statistical model of regional metabolic covariation. We studied 10 TS patients (mean age, 41.5 +/- 12.7 years) who were either drug naive or medication free for at least 2 years. Ten normal volunteers (mean age, 42.5 +/- 11.5) served as controls. We used quantitative FDG/PET to calculate global, regional, and normalized rates of glucose metabolism (GMR, rCMRGlc, and rCMRGlc/GMR) in all subjects. The Scaled Subprofile Model (SSM) was used to identify specific patterns of regional metabolic covariation associated with TS. We found that global and regional metabolic rates were normal in TS. SSM analysis identified two TS-related brain networks. One pattern (15.8% variance accounted for, VAF) was characterized by covariate bilateral metabolic increases in lateral premotor and supplementary motor association cortices and in the midbrain. Individual patient expression of this pattern (subject score) was abnormally increased in the TS group (p < 0.01). A second pattern (10.5% VAF) was characterized by covariate decreases in caudate and thalamic metabolism associated with smaller reductions in lentiform and hippocampal metabolic activity. Subject scores for this pattern correlated with Tourette Syndrome Global Scale (TSGS) global ratings (r = 0.85, p < 0.005). We conclude that the metabolic landscape of TS is characterized by a nonspecific pattern of increased motor cortical activity identified in other hyperkinetic disorders. TS is also associated with a specific brain network characterized by a reduction in the activity of limbic basal ganglia-thalamocortical projection systems.

The focus of experimental therapeutics for Parkinson disease (PD) is on neuroprotection to slow progression.1 However, patients with PD need better symptomatic treatments, especially patients with advanced disease with motor fluctuations. PD is a disorder of dopaminergic neurons, so dopamine replacement strategies are the most effective symptomatic treatments. However, these strategies may have long-term complications such as motor fluctuations and dyskinesias. Current nondopaminergic therapies such as anticholinergics provide relatively little benefit to a minority of patients. Adenosine antagonists have long been thought to have potential for treatment of PD.2 Clinical trials of the nonselective adenosine antagonists caffeine and theophylline, however, have been unimpressive.2-4⇓⇓ In animal models of PD, selective adenosine A2A receptor antagonists enhance dopamine benefit—importantly, without worsening dyskinesias.5,6⇓ This issue of Neurology reports the …