GBA Variants are associated with a distinct pattern of cognitive deficits in Parkinson's disease.

BACKGROUND: Loss-of-function mutations in the GBA gene are associated with more severe cognitive impairment in PD, but the nature of these deficits is not well understood and whether common GBA polymorphisms influence cognitive performance in PD is not yet known. METHODS: We screened the GBA coding region for mutations and the E326K polymorphism in 1,369 PD patients enrolled at eight sites from the PD Cognitive Genetics Consortium. Participants underwent assessments of learning and memory (Hopkins Verbal Learning Test-Revised), working memory/executive function (Letter-Number Sequencing Test and Trail Making Test A and B), language processing (semantic and phonemic verbal fluency), visuospatial abilities (Benton Judgment of Line Orientation), and global cognitive function (MoCA). We used linear regression to test for association between genotype and cognitive performance with adjustment for important covariates and accounted for multiple testing using Bonferroni's corrections. RESULTS: Mutation carriers (n = 60; 4.4%) and E326K carriers (n = 65; 4.7%) had a higher prevalence of dementia (mutations, odds ratio = 5.1; P = 9.7 × 10(-6) ; E326K, odds ratio = 6.4; P = 5.7 × 10(-7) ) and lower performance on Letter-Number Sequencing (mutations, corrected P[Pc ] = 9.0 × 10(-4) ; E326K, Pc = 0.036), Trail Making B-A (mutations, Pc = 0.018; E326K, Pc = 0.018), and Benton Judgment of Line Orientation (mutations, Pc = 0.0045; E326K, Pc = 0.0013). CONCLUSIONS: Both GBA mutations and E326K are associated with a distinct cognitive profile characterized by greater impairment in working memory/executive function and visuospatial abilities in PD patients. The discovery that E326K negatively impacts cognitive performance approximately doubles the proportion of PD patients we now recognize are at risk for more severe GBA-related cognitive deficits.

Effect of Deutetrabenazine on Chorea Among Patients With Huntington Disease: A Randomized Clinical Trial.

IMPORTANCE: Deutetrabenazine is a novel molecule containing deuterium, which attenuates CYP2D6 metabolism and increases active metabolite half-lives and may therefore lead to stable systemic exposure while preserving key pharmacological activity. OBJECTIVE: To evaluate efficacy and safety of deutetrabenazine treatment to control chorea associated with Huntington disease. DESIGN, SETTING, AND PARTICIPANTS: Ninety ambulatory adults diagnosed with manifest Huntington disease and a baseline total maximal chorea score of 8 or higher (range, 0-28; lower score indicates less chorea) were enrolled from August 2013 to August 2014 and randomized to receive deutetrabenazine (n = 45) or placebo (n = 45) in a double-blind fashion at 34 Huntington Study Group sites. INTERVENTIONS: Deutetrabenazine or placebo was titrated to optimal dose level over 8 weeks and maintained for 4 weeks, followed by a 1-week washout. MAIN OUTCOMES AND MEASURES: Primary end point was the total maximal chorea score change from baseline (the average of values from the screening and day-0 visits) to maintenance therapy (the average of values from the week 9 and 12 visits) obtained by in-person visits. This study was designed to detect a 2.7-unit treatment difference in scores. The secondary end points, assessed hierarchically, were the proportion of patients who achieved treatment success on the Patient Global Impression of Change (PGIC) and on the Clinical Global Impression of Change (CGIC), the change in 36-Item Short Form- physical functioning subscale score (SF-36), and the change in the Berg Balance Test. RESULTS: Ninety patients with Huntington disease (mean age, 53.7 years; 40 women [44.4%]) were enrolled. In the deutetrabenazine group, the mean total maximal chorea scores improved from 12.1 (95% CI, 11.2-12.9) to 7.7 (95% CI, 6.5-8.9), whereas in the placebo group, scores improved from 13.2 (95% CI, 12.2-14.3) to 11.3 (95% CI, 10.0-12.5); the mean between-group difference was -2.5 units (95% CI, -3.7 to -1.3) (P < .001). Treatment success, as measured by the PGIC, occurred in 23 patients (51%) in the deutetrabenazine group vs 9 (20%) in the placebo group (P = .002). As measured by the CGIC, treatment success occurred in 19 patients (42%) in the deutetrabenazine group vs 6 (13%) in the placebo group (P = .002). In the deutetrabenazine group, the mean SF-36 physical functioning subscale scores decreased from 47.5 (95% CI, 44.3-50.8) to 47.4 (44.3-50.5), whereas in the placebo group, scores decreased from 43.2 (95% CI, 40.2-46.3) to 39.9 (95% CI, 36.2-43.6), for a treatment benefit of 4.3 (95% CI, 0.4 to 8.3) (P = .03). There was no difference between groups (mean difference of 1.0 unit; 95% CI, -0.3 to 2.3; P = .14), for improvement in the Berg Balance Test, which improved by 2.2 units (95% CI, 1.3-3.1) in the deutetrabenazine group and by 1.3 units (95% CI, 0.4-2.2) in the placebo group. Adverse event rates were similar for deutetrabenazine and placebo, including depression, anxiety, and akathisia. CONCLUSIONS AND RELEVANCE: Among patients with chorea associated with Huntington disease, the use of deutetrabenazine compared with placebo resulted in improved motor signs at 12 weeks. Further research is needed to assess the clinical importance of the effect size and to determine longer-term efficacy and safety. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT01795859.

Computer-Guided Deep Brain Stimulation Programming for Parkinson's Disease.

OBJECTIVE: Pilot study to evaluate computer-guided deep brain stimulation (DBS) programming designed to optimize stimulation settings using objective motion sensor-based motor assessments. MATERIALS AND METHODS: Seven subjects (five males; 54-71 years) with Parkinson's disease (PD) and recently implanted DBS systems participated in this pilot study. Within two months of lead implantation, the subject returned to the clinic to undergo computer-guided programming and parameter selection. A motion sensor was placed on the index finger of the more affected hand. Software guided a monopolar survey during which monopolar stimulation on each contact was iteratively increased followed by an automated assessment of tremor and bradykinesia. After completing assessments at each setting, a software algorithm determined stimulation settings designed to minimize symptom severities, side effects, and battery usage. RESULTS: Optimal DBS settings were chosen based on average severity of motor symptoms measured by the motion sensor. Settings chosen by the software algorithm identified a therapeutic window and improved tremor and bradykinesia by an average of 35.7% compared with baseline in the "off" state (p < 0.01). CONCLUSIONS: Motion sensor-based computer-guided DBS programming identified stimulation parameters that significantly improved tremor and bradykinesia with minimal clinician involvement. Automated motion sensor-based mapping is worthy of further investigation and may one day serve to extend programming to populations without access to specialized DBS centers.

Cognitive profile of LRRK2-related Parkinson's disease.

BACKGROUND: Increasing evidence suggests that genetic factors play a role in the variability associated with cognitive performance in Parkinson's disease (PD). Mutations in the LRRK2 gene are the most common cause of monogenic PD; however, the cognitive profile of LRRK2-related PD is not well-characterized. METHODS: A cohort of 1,447 PD patients enrolled in the PD Cognitive Genetics Consortium was screened for LRRK2 mutations and completed detailed cognitive testing. Associations between mutation carrier status and cognitive test scores were assessed using linear regression models. RESULTS: LRRK2 mutation carriers (n = 29) demonstrated better performance on the Mini Mental State Examination (P = 0.03) and the Letter-Number Sequencing Test (P = 0.005). A smaller proportion of LRRK2 carriers were demented (P = 0.03). CONCLUSIONS: Our cross-sectional study demonstrates better performance on certain cognitive tests, as well as lower rates of dementia in LRRK2-related PD. Future longitudinal studies are needed to determine whether LRRK2 mutation carriers exhibit slower cognitive decline. © 2015 International Parkinson and Movement Disorder Society.

Evaluation of mild cognitive impairment subtypes in Parkinson's disease.

Mild cognitive impairment in Parkinson's disease (PD-MCI) is common and increases the risk for dementia. Establishing distinct PD-MCI cognitive subtypes could be valuable for eventually predicting those most likely to convert to dementia. However, the study of PD-MCI subtypes has not yielded consistent results among cohorts. To determine whether there are distinct cognitive subtypes among participants diagnosed with PD-MCI in the Pacific Northwest Udall Center Clinical Consortium, we cognitively subtyped 95 patients with PD-MCI, using the Movement Disorders Society Task Force diagnostic guidelines. Psychometric test scores were then subjected to principle components factor analysis to determine whether similar cognitive subgroups could be identified using statistical methodology. Multiple-domain PD-MCI was diagnosed in 95% of the sample, and a range of cognitive impairments were noted. Factor analysis yielded seven factors and demonstrated overlap of phonemic verbal fluency on two factors, as well as the loading of verbal fluency on the same factor as a visuospatial measure; however, these factors did not partition the sample into distinct cognitive subtypes. Separation of cognitive subtypes based on the current PD-MCI criteria, or via statistical methods, may not provide sufficient information to describe distinct PD groups. Future efforts to validate the PD-MCI criteria and identify combinations of genetic or other risk factors for cognitive impairment are warranted.

The Feasibility and Efficacy of a Virtual Reality Tandem Cycling Program for Persons with Parkinson's Disease and Their Care Partners.

INTRODUCTION: Persons with Parkinson's disease (PwPD) suffer from motor and non-motor symptoms which significantly affect their quality of life (QoL), and the QoL of their care partners (CP). Tandem cycling reduces PwPD motor symptoms; however, no studies have examined other benefits or included PwPD CP. We conducted an 8-week community virtual reality (VR) tandem cycling intervention to assess the feasibility and efficacy for PwPD and their CP (i.e., PD dyads). We hypothesized that dyadic tandem cycling would improve (1) PwPD motor and non-motor symptoms and (2) dimensions of PD dyads' QoL and physiologic health. METHODS: Ten PD dyads were recruited to complete 8 weeks of progressive intensity, bi-weekly tandem cycling. At pre- and post-testing, PwPD were assessed using the Movement Disorder Society-Unified Parkinson's Disease Rating Scale-III (MDS-UPDRS-III), functional gait assessment (FGA), and 10-m gait speed test. PD dyads also completed emotional and cognitive status questionnaires [e.g., Geriatric Depression Scale-Short Form (GDS-SF)], and wore BodyGuard 2 heart rate (HR) monitors for 48 h to assess surrogate measures of heart rate variability. Statistical analyses were conducted using Student's t tests with significance set at p ≤ 0.05. RESULTS: Eight PD dyads and one PwPD completed the intervention. Retention of PwPD (90%) and CP (80%) was adequate, and PD dyad adherence ranged from 91.67 to 97.91%. PwPD demonstrated significant clinical improvements in MDS-UPDRS-III scores (- 7.38, p < 0.01), FGA scores (+ 3.50, p < 0.01), and 10-m gait speed times (+ 0.27 m/s, p < 0.01), in addition to significant self-reported improvements in mobility (- 13.61, p = 0.02), fatigue (- 5.99, p = 0.02), and social participation (+ 4.69, p < 0.01). CP depressive symptoms significantly decreased (- 0.88, p = 0.02), and PD dyads shared a significant increase in root mean square of the successive differences (RMSSD; p = 0.04). CONCLUSION: Our pilot study demonstrated feasibility and multiple areas of efficacy supporting further investigation of community VR tandem cycling as a therapeutic intervention for PD dyads.

Tricyclic antidepressants delay the need for dopaminergic therapy in early Parkinson's disease.

This study examined whether antidepressants delay the need for dopaminergic therapy or change the degree of motor impairment and disability in a population of early Parkinson's disease (PD) patients. Preclinical studies have indicated that antidepressants modulate signaling pathways involved in cell survival and plasticity, suggesting they may serve to both treat PD-associated depression and slow disease progression. A patient-level meta-analysis included 2064 patients from the treatment and placebo arms of the following trials: FS1, FS-TOO, ELLDOPA, QE2, TEMPO, and PRECEPT. Depression severity was determined at baseline, and antidepressant use was reported in a medication log each visit. Kaplan-Meier curves and time-dependent Cox proportional hazards models determined associations between depression severity and antidepressant use with the primary outcome, time to initiation of dopaminergic therapy. ANCOVAs determined associations with the secondary outcome, degree of motor impairment and disability, reported as annualized change in UPDRS scores from baseline to final visit. When controlling for baseline depression, the initiation of dopaminergic therapy was delayed for subjects taking tricyclic antidepressants compared with those not taking antidepressants. No significant differences were found in UPDRS scores for subjects taking antidepressants compared with those not taking antidepressants. Tricyclic antidepressants are associated with a delay in reaching the end point of need to start dopaminergic therapy. The lack of change in overall UPDRS scores suggests the delay was not attributable to symptomatic effects.

Differential response of speed, amplitude, and rhythm to dopaminergic medications in Parkinson's disease.

Although movement impairment in Parkinson's disease includes slowness (bradykinesia), decreased amplitude (hypokinesia), and dysrhythmia, clinicians are instructed to rate them in a combined 0-4 severity scale using the Unified Parkinson's Disease Rating Scale motor subscale. The objective was to evaluate whether bradykinesia, hypokinesia, and dysrhythmia are associated with differential motor impairment and response to dopaminergic medications in patients with Parkinson's disease. Eighty five Parkinson's disease patients performed finger-tapping (item 23), hand-grasping (item 24), and pronation-supination (item 25) tasks OFF and ON medication while wearing motion sensors on the most affected hand. Speed, amplitude, and rhythm were rated using the Modified Bradykinesia Rating Scale. Quantitative variables representing speed (root mean square angular velocity), amplitude (excursion angle), and rhythm (coefficient of variation) were extracted from kinematic data. Fatigue was measured as decrements in speed and amplitude during the last 5 seconds compared with the first 5 seconds of movement. Amplitude impairments were worse and more prevalent than speed or rhythm impairments across all tasks (P < .001); however, in the ON state, speed scores improved exclusively by clinical (P < 10(-6) ) and predominantly by quantitative (P < .05) measures. Motor scores from OFF to ON improved in subjects who were strictly bradykinetic (P < .01) and both bradykinetic and hypokinetic (P < 10(-6) ), but not in those strictly hypokinetic. Fatigue in speed and amplitude was not improved by medication. Hypokinesia is more prevalent than bradykinesia, but dopaminergic medications predominantly improve the latter. Parkinson's disease patients may show different degrees of impairment in these movement components, which deserve separate measurement in research studies. © 2011 Movement Disorder Society.

The modified bradykinesia rating scale for Parkinson's disease: reliability and comparison with kinematic measures.

Bradykinesia encompasses slowness, decreased movement amplitude, and dysrhythmia. Unified Parkinson's Disease Rating Scale-based bradykinesia-related items require that clinicians condense abnormalities in speed, amplitude, fatiguing, hesitations, and arrests into a single score. The objective of this study was to evaluate the reliability of a modified bradykinesia rating scale, which separately assesses speed, amplitude, and rhythm and its correlation with kinematic measures from motion sensors. Fifty patients with Parkinson's disease performed Unified Parkinson's Disease Rating Scale-directed finger tapping, hand grasping, and pronation-supination while wearing motion sensors. Videos were rated blindly and independently by 4 clinicians. The modified bradykinesia rating scale and Unified Parkinson's Disease Rating Scale demonstrated similar inter- and intrarater reliability. Raters placed greater weight on amplitude than on speed or rhythm when assigning a Unified Parkinson's Disease Rating Scale score. Modified bradykinesia rating scale scores for speed, amplitude, and rhythm correlated highly with quantitative kinematic variables. The modified bradykinesia rating scale separately captures bradykinesia components with interrater and intrarater reliability similar to that of the Unified Parkinson's Disease Rating Scale. Kinematic sensors can accurately quantify speed, amplitude, and rhythm to aid in the development and evaluation of novel therapies in Parkinson's disease.

Opsoclonus-Myoclonus-Ataxia Syndrome (OMAS) Associated with SARS-CoV-2 Infection: Post-Infectious Neurological Complication with Benign Prognosis.

The novel coronavirus SARS-CoV-2 (severe acute respiratory syndrome coronavirus-2) is the cause of the COVID-19 pandemic [5]. SARS-Cov-2 demonstrates partial resemblance to SARS-CoV and MERS-CoV in phylogenetic analysis, clinical manifestations, and pathological findings [6, 7]. Reports emerging from China have described ataxia as a neurological symptom of the SARS-CoV-2 infection [5]. Opsoclonus consists of back-to-back multidirectional conjugate saccades without an inter-saccadic interval [8]. Myoclonus is defined as a sudden, brief, "shock-like", nonepileptic involuntary movement [9], which has been described as a symptom of SARS-CoV-2 infection [10]. Opsoclonus-Myoclonus-Ataxia syndrome (OMAS) associated COVID-19 infection has been reported recently [1112].

Juvenile levodopa-responsive Parkinsonism with early orobuccolingual dyskinesias and cognitive impairment.

A 13-year old girl presented with slowly progressive rest tremor of the hands, bradykinesia, and rigidity. The symptoms improved with dopaminergic medications, but severe drug-induced dyskinesias developed early. She subsequently developed cognitive slowing and difficulty initiating saccadic eye movements. She went on to have deep brain stimulation surgery. Experts discuss the syndromal diagnosis and predict the underlying pathology. The pathological diagnosis is given and clinical learning points are considered.

Effect of using a wearable device on clinical decision-making and motor symptoms in patients with Parkinson's disease starting transdermal rotigotine patch: A pilot study.

BACKGROUND: Feedback from wearable biosensors may help assess motor function in Parkinson's disease (PD) patients and titrate medication. Kinesia 360 continuously monitors motor symptoms via wrist and ankle sensors. METHODS: PD0049 was a 12-week pilot study to investigate whether using Kinesia 360 at home could improve motor symptom management in PD patients starting transdermal dopamine agonist rotigotine. Adults with PD and insufficiently controlled motor symptoms (prescribed rotigotine) were randomized 1:1 to Control Group (CG) or Experimental Group (EG) before starting rotigotine. Motor symptoms were assessed in all patients at baseline and Week 12 (W12) using Unified PD Rating Scale (UPDRS) III and Kinesia ONE, which measures standardized motor tasks via a sensor on the index finger. Between baseline and W12, EG used Kinesia 360 at home; clinicians used the data to supplement standard care in adjusting rotigotine dosage. RESULTS: At W12, least squares mean improvements in UPDRS II (-2.1 vs 0.5, p = 0.004) and UPDRS III (-5.3 vs -1.0, p = 0.134) were clinically meaningfully greater, and mean rotigotine dosage higher (4.8 vs 3.9 mg/24 h) in EG (n = 19) vs CG (n = 20). Mean rotigotine dosage increase (+2.8 vs + 1.9 mg/24 h) and mean number of dosage changes (2.8 vs 1.8) during the study were higher in EG vs CG. Tolerability and retention rates were similar. CONCLUSION: Continuous, objective, motor symptom monitoring using a wearable biosensor as an adjunct to standard care may enhance clinical decision-making, and may improve outcomes in PD patients starting rotigotine.

Deep brain stimulation of the ventral intermediate nucleus of the thalamus in medically refractory orthostatic tremor: preliminary observations.

Orthostatic tremor (OT) is a disabling movement disorder associated with postural and gait impairment in the elderly. Medical therapy often yields insufficient benefit. We report the clinical and electrophysiological data on two patients with medication-refractory OT treated with deep brain stimulation of the ventral intermediate thalamic nucleus (Vim DBS). Patient 1 underwent bilateral deep brain stimulation (DBS) and Patient 2 unilateral Vim DBS following 28 and 30 years of disease duration, respectively. Both patients showed increased latency to symptom onset after rising from a seated position, improved tolerance for prolonged standing, and slower crescendo of tremor severity when remaining upright. Postoperative evaluation demonstrated decreased amplitude of electromyographic activity with persistence of well-defined oscillatory behavior showing strong coherence at 15 Hz between all muscles tested in the upper and lower limbs. Postural sway was unchanged. Clinical benefits have been sustained for over 18 months in Patient 1, and receded after 3 months in Patient 2. These findings support the consideration of bilateral Vim DBS implantation as a therapeutic option in patients with medically refractory OT. Further efficacy studies on chronic stimulation to disrupt the abnormal oscillatory activity in this disorder are warranted.

Large-scale exploratory genetic analysis of cognitive impairment in Parkinson's disease.

Cognitive impairment is a common and disabling problem in Parkinson's disease (PD). Identification of genetic variants that influence the presence or severity of cognitive deficits in PD might provide a clearer understanding of the pathophysiology underlying this important nonmotor feature. We genotyped 1105 PD patients from the PD Cognitive Genetics Consortium for 249,336 variants using the NeuroX array. Participants underwent assessments of learning and memory (Hopkins Verbal Learning Test-Revised [HVLT-R]), working memory/executive function (Letter-Number Sequencing and Trail Making Test [TMT] A and B), language processing (semantic and phonemic verbal fluency), visuospatial abilities (Benton Judgment of Line Orientation [JoLO]), and global cognitive function (Montreal Cognitive Assessment). For common variants, we used linear regression to test for association between genotype and cognitive performance with adjustment for important covariates. Rare variants were analyzed using the optimal unified sequence kernel association test. The significance threshold was defined as a false discovery rate-corrected p-value (PFDR) of 0.05. Eighteen common variants in 13 genomic regions exceeded the significance threshold for one of the cognitive tests. These included GBA rs2230288 (E326K; PFDR = 2.7 × 10-4) for JoLO, PARP4 rs9318600 (PFDR = 0.006), and rs9581094 (PFDR = 0.006) for HVLT-R total recall, and MTCL1 rs34877994 (PFDR = 0.01) for TMT B-A. Analysis of rare variants did not yield any significant gene regions. We have conducted the first large-scale PD cognitive genetics analysis and nominated several new putative susceptibility genes for cognitive impairment in PD. These results will require replication in independent PD cohorts.

Surgical treatment of movement disorders.

A substantial body of evidence has accumulated regarding the efficacy and safety of neurosurgery for Parkinson's disease, essential tremor, and dystonia. Surgery for movement disorders (thalamotomy, pallidotomy, and subthalamic nucleotomy or subthalamotomy) was largely ablative (lesion-based). Given the safety and anatomy-preservation advantage, long-term electrical stimulation of these same targets (thalamus, globus pallidus, and subthalamic nucleus) is discussed as the treatment of choice. High-frequency deep brain stimulation procedures replicate the effects of ablative interventions, but do not require making a destructive brain lesion. This article outlines patient eligibility for surgery, targeting techniques, intraoperative findings, and potential complications and discusses the outcomes expected for each of the major interventions for which clinical trial data are available.

Diagnostic performance of the "Huffing and Puffing" sign in psychogenic (functional) movement disorders.

OBJECTIVE: To determine the diagnostic value of effort-associated behaviors ("huffing and puffing" spectrum) in patients with psychogenic movement disorders. METHODS: Three blinded clinicians rated presence, severity, and duration of effort-associated features during standing and walking tasks on edited videos of 131 patients with psychogenic gait disorders and 37 patients with organic gait disorders. RESULTS: Huffing, grunting, grimacing, and breath holding were the most common effort-associated behaviors in patients with psychogenic gait disorders, with a combined prevalence of 44% and disproportionate to the severity of gait impairment compared to organic gait disorders. The presence of "huffing and puffing"-type behaviors yielded a relatively low sensitivity but high specificity for the diagnosis of psychogenic movement disorders, increasing the odds of diagnosis 13-fold (95%, CI: 4.2-43.8) compared to organic gait disorders. CONCLUSIONS: Demonstration of effort-associated behaviors during standing and walking strongly supports the psychogenic nature of disorders when gait is involved.

The RAB39B p.G192R mutation causes X-linked dominant Parkinson's disease.

OBJECTIVE: To identify the causal gene in a multi-incident U.S. kindred with Parkinson's disease (PD). METHODS: We characterized a family with a classical PD phenotype in which 7 individuals (5 males and 2 females) were affected with a mean age at onset of 46.1 years (range, 29-57 years). We performed whole exome sequencing on 4 affected and 1 unaffected family members. Sanger-sequencing was then used to verify and genotype all candidate variants in the remainder of the pedigree. Cultured cells transfected with wild-type or mutant constructs were used to characterize proteins of interest. RESULTS: We identified a missense mutation (c.574G > A; p.G192R) in the RAB39B gene that closely segregated with disease and exhibited X-linked dominant inheritance with reduced penetrance in females. The mutation occurred in a highly conserved amino acid residue and was not observed among 87,725 X chromosomes in the Exome Aggregation Consortium dataset. Sequencing of the RAB39B coding region in 587 familial PD cases yielded two additional mutations (c.428C > G [p.A143G] and c.624_626delGAG [p.R209del]) that were predicted to be deleterious in silico but occurred in families that were not sufficiently informative to assess segregation with disease. Experiments in PC12 and SK-N-BE(2)C cells demonstrated that p.G192R resulted in mislocalization of the mutant protein, possibly by altering the structure of the hypervariable C-terminal domain which mediates intracellular targeting. CONCLUSIONS: Our findings implicate RAB39B, an essential regulator of vesicular-trafficking, in clinically typical PD. Further characterization of normal and aberrant RAB39B function might elucidate important mechanisms underlying neurodegeneration in PD and related disorders.

Spatial reorganization of putaminal dopamine D2-like receptors in cranial and hand dystonia.

The putamen has a somatotopic organization of neurons identified by correspondence of firing rates with selected body part movements, as well as by complex, but organized, differential cortical projections onto putamen. In isolated focal dystonia, whole putaminal binding of dopamine D2-like receptor radioligands is quantitatively decreased, but it has not been known whether selected parts of the putamen are differentially affected depending upon the body part affected by dystonia. The radioligand [(18)F]spiperone binds predominantly to D2-like receptors in striatum. We hypothesized that the spatial location of [(18)F]spiperone binding within the putamen would differ in patients with dystonia limited to the hand versus the face, and we tested that hypothesis using positron emission tomography and magnetic resonance imaging. To address statistical and methodological concerns, we chose a straightforward but robust image analysis method. An automated algorithm located the peak location of [(18)F]spiperone binding within the striatum, relative to a brain atlas, in each of 14 patients with cranial dystonia and 8 patients with hand dystonia. The mean (left and right) |x|, y, and z coordinates of peak striatal binding for each patient were compared between groups by t test. The location of peak [(18)F]spiperone binding within the putamen differed significantly between groups (cranial dystonia z

APOE, MAPT, and SNCA genes and cognitive performance in Parkinson disease.

IMPORTANCE: Cognitive impairment is a common and disabling problem in Parkinson disease (PD) that is not well understood and is difficult to treat. Identification of genetic variants that influence the rate of cognitive decline or pattern of early cognitive deficits in PD might provide a clearer understanding of the etiopathogenesis of this important nonmotor feature. OBJECTIVE: To determine whether common variation in the APOE, MAPT, and SNCA genes is associated with cognitive performance in patients with PD. DESIGN, SETTING, AND PARTICIPANTS: We studied 1079 PD patients from 6 academic centers in the United States who underwent assessments of memory (Hopkins Verbal Learning Test-Revised [HVLT-R]), attention and executive function (Letter-Number Sequencing Test and Trail Making Test), language processing (semantic and phonemic verbal fluency tests), visuospatial skills (Benton Judgment of Line Orientation test), and global cognitive function (Montreal Cognitive Assessment). Participants underwent genotyping for the APOE ε2/ε3/ε4 alleles, MAPT H1/H2 haplotypes, and SNCA rs356219. We used linear regression to test for association between genotype and baseline cognitive performance with adjustment for age, sex, years of education, disease duration, and site. We used a Bonferroni correction to adjust for the 9 comparisons that were performed for each gene. MAIN OUTCOMES AND MEASURES: Nine variables derived from 7 psychometric tests. RESULTS: The APOE ε4 allele was associated with lower performance on the HVLT-R Total Recall (P = 6.7 × 10(-6); corrected P [Pc] = 6.0 × 10(-5)), Delayed Recall (P = .001; Pc = .009), and Recognition Discrimination Index (P = .004; Pc = .04); a semantic verbal fluency test (P = .002; Pc = .02); the Letter-Number Sequencing Test (P = 1 × 10(-5); Pc = 9 × 10(-5)); and Trail Making Test B minus Trail Making Test A (P = .002; Pc = .02). In a subset of 645 patients without dementia, the APOE ε4 allele was associated with lower scores on the HVLT-R Total Recall (P = .005; Pc = .045) and the semantic verbal fluency (P = .005; Pc = .045) measures. Variants of MAPT and SNCA were not associated with scores on any tests. CONCLUSIONS AND RELEVANCE: Our data indicate that the APOE ε4 allele is an important predictor of cognitive function in PD across multiple domains. Among PD patients without dementia, the APOE ε4 allele was only associated with lower performance on word list learning and semantic verbal fluency, a pattern more typical of the cognitive deficits seen in early Alzheimer disease than PD.