Executive functions in premanifest Huntington's disease.

BACKGROUND: We investigated the viability of psychometrically robust executive function measures as markers for premanifest Huntington's disease (HD). METHODS: Fifteen premanifest HD subjects and 42 controls were compared on the NIH EXAMINER executive function battery. This battery yields an overall executive composite score, plus working memory, cognitive control, and fluency scores that are measured on psychometrically matched scales. The scores were correlated with two disease markers, disease burden and striatal volumes, in the premanifest HD subjects. RESULTS: The premanifest HD subjects scored significantly lower on the working memory score. The executive composite positively correlated with striatal volumes, and the working memory score negatively correlated with disease burden. The cognitive control and fluency scores did not differ between the groups or correlate significantly with the disease markers. CONCLUSIONS: The NIH EXAMINER executive composite and working memory scores are sensitive markers of cognitive dysfunction, striatal volume, and disease burden in premanifest HD.

Rivastigmine is associated with restoration of left frontal brain activity in Parkinson's disease.

The objective of this study was to investigate how acetylcholinesterase inhibitor (ChEI) treatment affects brain function in Parkinson's disease (PD). Twelve patients with PD and either dementia or mild cognitive impairment underwent task-free functional magnetic resonance imaging before and after 3 months of ChEI treatment and were compared with 15 age- and sex-matched neurologically healthy controls. Regional spontaneous brain activity was measured using the fractional amplitude of low-frequency fluctuations. At baseline, patients showed reduced spontaneous brain activity in regions important for motor control (eg, caudate, supplementary motor area, precentral gyrus, thalamus), attention and executive functions (eg, lateral prefrontal cortex), and episodic memory (eg, precuneus, angular gyrus, hippocampus). After treatment, the patients showed a similar but less extensive pattern of reduced spontaneous brain activity relative to controls. Spontaneous brain activity deficits in the left premotor cortex, inferior frontal gyrus, and supplementary motor area were restored such that the activity was increased posttreatment compared with baseline and was no longer different from controls. Treatment-related increases in left premotor and inferior frontal cortex spontaneous brain activity correlated with parallel reaction time improvement on a test of controlled attention. PD patients with cognitive impairment show numerous regions of decreased spontaneous brain function compared with controls, and rivastigmine is associated with performance-related normalization in the left frontal cortex function.

Regional alterations of brain microstructure in Parkinson's disease using diffusion tensor imaging.

This study tested the hypothesis that diffusion tensor imaging can detect alteration in microscopic integrity of white matter and basal ganglia regions known to be involved in Parkinson's disease (PD) pathology. It was also hypothesized that there is an association between diffusion abnormality and PD severity and subtype. Diffusion tensor imaging at 4 Tesla was obtained in 12 PD and 20 control subjects, and measures of fractional anisotropy and mean diffusivity were evaluated using both region-of-interest and voxel-based methods. Movement deficits and subtypes in PD subjects were assessed using the Motor Subscale (Part III) of the Unified Parkinson's Disease Rating Scale. Reduced fractional anisotropy (P < .05, corrected) was found in PD subjects in regions related to the precentral gyrus, substantia nigra, putamen, posterior striatum, frontal lobe, and the supplementary motor areas. Reduced fractional anisotropy in the substantia nigra correlated (P < .05, corrected) with the increased rating scale motor scores. Significant spatial correlations between fractional anisotropy alterations in the putamen and other PD-affected regions were also found in the context of PD subtypes index analysis. Our data suggest that microstructural alterations detected with diffusion tensor might serve as a potential biomarker for PD.

Long-term follow-up of pallidal deep brain stimulation in two cases of Huntington's disease.

BACKGROUND: Deep brain stimulator (DBS) implantation has been shown to be effective in the treatment of various movement disorders including Parkinson's disease, essential tremor and dystonia. However, there is limited information regarding the potential use of DBS in Huntington's disease (HD). In this study, the authors present their findings on the long-term motor and neurocognitive results of two HD patients (patient 1: 57 years, 42 cytosine-adenine guanine (CAG) repeats; patient 2: 50 years, 41 CAG repeats) who underwent staged bilateral globus pallidus interna DBS surgery. METHODS: The patients were evaluated at baseline and at five timepoints throughout a 2-year postoperative during which motoric ratings ((Unified Huntington's Disease Rating Scale), Activities of Daily Living scores (HD-ADL) and neurocognitive testing) were obtained. RESULTS: Both patients had a sustained decline in chorea 2 years after initial DBS surgery. Despite this improvement in chorea, one patient has had continuing deterioration in gait, bradykinesia and dystonia scores, which has caused his ability to perform activities of daily living to return to his baseline level of functioning prior to DBS surgery. Both patients have experienced further gradual decline in neurocognitive functioning, which appears to be independent of DBS and most likely related to disease progression. CONCLUSION: DBS implantation may be a potential treatment option for a subset of HD patients who have significant functional deficits due to chorea. However, appropriate selection of the best candidates for DBS appears to be challenging, given the difficulty in predicting disease course in HD due to its variable nature.

Role of tetrabenazine for Huntington's disease-associated chorea.

OBJECTIVE: To review the pharmacology, pharmacokinetics, efficacy, and safety of tetrabenazine for the treatment of Huntington's disease (HD)-associated chorea. DATA SOURCES: Primary literature and review articles were obtained through a PubMed search (1959-November 2009) using the terms tetrabenazine, HD, chorea, and hyperkinetic movement disorders. A bibliographic search was performed on selected articles. STUDY SELECTION AND DATA EXTRACTION: All English-language articles identified from the data sources were reviewed. Studies including greater than 10 patients and a direct comparative study with primarily HD-associated chorea were included in the review. DATA SYNTHESIS: Tetrabenazine is the first drug approved by the Food and Drug Administration (FDA) for the management of HD-associated chorea. Tetrabenazine binds reversibly to the type 2 vesicular monoamine transporters and has been shown to inhibit monoamine uptake in presynaptic vesicles, resulting in monoamine depletion. The duration of the antichorea effect of tetrabenazine has been reported to be approximately 5.5 hours. Tetrabenazine is extensively metabolized hepatically by the CYP2D6 enzyme to its primary active metabolite, alpha-dihydrotetrabenazine. The half-life of alpha-dihydrotetrabenazine is 4-8 hours. Clinical trials demonstrated that tetrabenazine reduces chorea, on average, by 5 units based upon the chorea score from the Unified Huntington's Disease Rating Scale. The most common adverse effects reported include sedation, drowsiness, parkinsonism, and depression. Rarely, corrected QT interval prolongation, orthostatic hypotension, and hyperprolactinemia have been reported. Tetrabenazine also has a black box warning for increasing the risk of depression and suicidality. CONCLUSIONS: Tetrabenazine can provide significant benefit in the treatment of chorea associated with HD. Given the potential adverse effects of tetrabenazine, health-care providers need to screen patients carefully prior to initiating treatment with this medication. In the future, additional long-term and comparative studies would be useful for further clarification of the role of tetrabenazine in the treatment of HD-associated chorea.

Zonisamide for essential tremor: an evaluator-blinded study.

In this evaluator-blinded open-treatment trial, subjects with moderate/severe upper limb essential tremor were titrated to 300 mg/day zonisamide, or adjusted to a lesser dose if symptoms warranted, as monotherapy or as adjunct to stable antitremor medication, followed by a 12-week extension phase. The primary efficacy outcome variables were blinded rater videotaped/drawing tremor score changes at the Treatment and Extension visits compared to Baseline, based on Fahn-Tolosa-Marin and Postural Tremor Scales. Subjects also rated Functional Disabilities. Primary outcomes showed reduced tremor scores at the Treatment (P < 0.00001, n = 25) and Extension (n = 16) visits, at mean doses of 252 and 225 mg/day, respectively. Subject ratings indicated 200 mg/day was superior to 100 mg/day, whereas 300 mg/day produced no additional benefit, but instead was associated with more adverse symptoms, most commonly somnolence, poor energy, imbalance, and altered taste. Future double-blind placebo-controlled trials are warranted.

Psychosis in nursing home patients with Parkinson's disease.

Psychosis in patients with Parkinson's disease (PD) is a common and important problem. It is a frequent cause of nursing home placement and is associated with a high mortality. The cause of psychosis in PD is usually multi-factorial but often involves the agents used to treat the motor symptoms of the disease. Treatment strategies should include ruling out other causes of cognitive decline, reducing anti-PD medications, and judicious use of atypical neuroleptic medications. Cholinesterase inhibitors can also be useful as an adjunctive agent in patients with psychosis and cognitive decline. Careful management of PD patients with psychosis can often result in good control of hallucinations and delusions without significant decline in motor function.

Refining the diagnosis of Huntington disease: the PREDICT-HD study.

Participants with the gene expansion for Huntington disease (HD) but not yet diagnosed were evaluated annually. Unidimensional diagnosis (UD) was a motor diagnosis defined as a diagnostic confidence level (DCL) of 4 (unequivocal motor signs, ≥99% confidence) on the standardized motor exam of the Unified Huntington Disease Rating Scale (UHDRS). Multidimensional diagnosis (MD) was defined as answering yes on Question 80 (Q80) of the UHDRS, ≥99% confidence of manifest HD based on the entire UHDRS. Motor, cognitive, and behavioral measures of phenotype at first diagnosis were compared by t-tests between participants diagnosed via motor exam (UD) and those diagnosed via multidimensional input (MD). Cluster analysis identified clusters based on UHDRS domains.186 participants received a diagnosis of HD during a maximum of 6.4 years of follow-up. In 108 (58.1%) the diagnosis by MD and UD occurred simultaneously, while in 69 (37.1%) the diagnosis by MD occurred prior to UD. Participants who were diagnosed by MD prior to UD were less impaired on motor (12.2 ± 6.7 vs. 22.4 ± 9.3, p < 0.0001), and cognitive (290.7 ± 56.2 vs. 258.0 ± 53.7, p = 0.0002), but not behavioral measures (16.3 ± 21.2 vs. 18.6 ± 22.1, p = 0.49) when compared with those diagnosed simultaneously. Cluster analysis identified three clusters that represented primarily cognitively impaired, behaviorally impaired, and cognitively preserved phenotypes. A multidimensional method results in an earlier diagnosis with less motor and cognitive impairment than a motor diagnosis. Findings have implications for designing preventive trials and providing clinical care in prodromal HD.

Pharmacist's role in a Parkinson's disease and movement disorders clinic.

PURPOSE: The expanding role of a clinical pharmacist at a Veterans Affairs (VA) out-patient clinic for patients with Parkinson's disease (PD) and movement disorders is described. SUMMARY: San Francisco VA Medical Center added a clinical pharmacist to the multi-disciplinary team serving patients at an outpatient clinic operated by its Parkinson's Disease Research, Education and Clinical Center (PADRECC). During the first six months after joining the clinic team, the pharmacist met with 131 patients and made a total of 69 drug therapy recommendations that were implemented by neurologists, clinical nurse specialists, and other PADRECC providers. The results of a retrospective chart review suggested that in about 21% of the cases evaluated, the pharmacist's recommendations contributed to an improved medical outcome or the resolution of a medical problem. Anonymous surveys indicated that clinic providers (n = 33) and patients (n = 20) were satisfied with the pharmacist's services. Using a five-point Likert scale (scores ranged from 1 for "strongly disagree" to 5 for "strongly agree") that they had more time to devote to other clinic responsibilities with the pharmacist present in the clinic (mean score, 4.79); patients indicated that they had an improved understanding of their medications after speaking with the pharmacist (mean score, 4.88). CONCLUSION: A clinical pharmacist's regular involvement in an outpatient PD and movement disorders clinic has been well received by patients and clinic providers. The study results suggest that the pharmacist has made important contributions in areas such as therapeutic problem solving and medication education while freeing up providers for other responsibilities.

Pallidal neuronal discharge in Huntington's disease: support for selective loss of striatal cells originating the indirect pathway.

Chorea is the predominant motor manifestation in the early symptomatic phase of adult onset Huntington's disease (HD). Pathologically, this stage is marked by differential loss of striatal neurons contributing to the indirect pathway. This pattern of neuronal loss predicts decreased neuronal firing rates in GPi and increased firing rates in GPe, the opposite of the changes in firing rate known to occur in Parkinson's disease (PD). We present single-unit discharge characteristics (33 neurons) observed in an awake patient with HD (41 CAG repeats) undergoing microelectrode guided surgery for pallidal deep brain stimulation. Pallidal single-unit activity at "rest" and during voluntary movement was discriminated off line by principal component analysis and evaluated with respect to discharge rate, bursting, and oscillatory activity in the 0-200 Hz range. 24 GPi and 9 GPe units were studied, and compared with 132 GPi and 50 GPe units from 14 patients with PD. The mean (+/-SEM) spontaneous discharge rate for HD was 58+/-4 for GPi and 73+/-5 for GPe. This contrasted with discharge rates in PD of 95+/-2 for GPi and 57+/-3 for GPe. HD GPi units showed more bursting than PD GPi units but much less oscillatory activity in the 2-35 Hz frequency range at rest. These findings are consistent with selective early loss of striatal cells originating the indirect pathway.

Clinical characteristics in early Parkinson's disease in a central California population-based study.

There is considerable variation in the phenotypic appearance of individuals with idiopathic Parkinson's disease (PD), which may translate into differences in disease progression in addition to underlying disease etiology. In this publication, we report on the demographic and clinical characteristics of 162 individuals diagnosed with clinically probable PD from January 1998 to June 2003 who resided in predominantly rural communities in central California. The majority of the subjects were Caucasian, male, and between 60 and 79 years of age. The akinetic-rigid and tremor-dominant subtypes were more common than the mixed subtype. The majority of subjects displayed motor signs of rigidity (92.0%), bradykinesia (95.7%), and gait problems (87.0%), whereas less than half (43.3%) of the subjects displayed a tremor. Three fourths of patients received a Hoehn and Yahr Scale score of Stage 2 or higher. One third of the patients were treated with levodopa, and patients under 60 years of age were more likely to be treated with dopamine agonists. Within 3 years after first diagnosis, 13% of subjects showed some signs of depression and 17% of subjects met criteria for mild dementia. Among our subjects, 17.3% reported a family history of PD in first- or second-degree relatives,15.4% a family history of essential tremor, and 14.2% of Alzheimer's disease. This study represents the most extensive phenotypic description of rural U.S. residents in the initial stages of PD who were recruited in a population-based manner; future follow-up may provide valuable information regarding the prognostic indication of these symptoms/signs and improve our understanding of the underlying etiology of PD.