Peter H. Kraus

Riluzole in Huntington's disease: a 3‐year, randomized controlled study

We conducted a randomized double‐blind trial of riluzole in Huntingtons disease to investigate the efficacy of this antiexcitotoxic drug in slowing disease progression.

Mitochondrial impairment in patients and asymptomatic mutation carriers of Huntington's disease

Huntingtons disease (HD) is an autosomal dominantly inherited neurodegenerative disorder caused by a CAG repeat expansion in the IT‐15 gene; however, it remains unknown how the mutation leads to selective neurodegeneration. Several lines of evidence suggest impaired mitochondrial function as a component of the neurodegenerative process in HD. We assessed energy metabolism in the skeletal muscle of 15 HD patients and 12 asymptomatic mutation carriers in vivo using 31P magnetic resonance spectroscopy. Phosphocreatine recovery after exercise is a direct measure of ATP synthesis and was slowed significantly in HD patients and mutation carriers in comparison to age‐ and gender‐matched healthy controls. We found that oxidative function is impaired to a similar extent in manifest HD patients and asymptomatic mutation carriers. Our findings suggest that mitochondrial dysfunction is an early and persistent component of the pathophysiology of HD.

NR2A and NR2B receptor gene variations modify age at onset in Huntington disease

Abstract. N -Methyl- d -aspartate (NMDA) receptor-mediated excitotoxicity has been proposed to play a role in the pathogenesis of Huntington disease (HD), an autosomal dominantly inherited disorder associated with defined expansions in a stretch of perfect CAG repeats in the 5′ part of the IT15 gene. The number of CAG repeat units is highly predictive for the age at onset (AO) in HD. However, AO is only modestly correlated with repeat length when the HD expansion range is in the high 30s or low 40s. Therefore, we investigated whether the genes for the different subunits composing the multimeric complexes of NMDA receptors (GRIN glutamate receptor, ionotropic, N -methyl- d -aspartate) represent candidates for modulating the AO of HD. In the studied cohort of 167 HD patients, the repeat range from 41 to 45 CAG units accounted for 30.8% of the variance in AO; 12.3% additional variance could be attributed to GRIN2B genotype variation and 4.5% to GRIN2A genotype variation. We conclude that these two genes, coding for NR2B and NR2A subtypes mainly expressed in the striatum, may influence the variability in AO of HD. Neuroprotective strategies for HD patients and persons at risk should be reconsidered in the light of these findings.

Testing objective measures of motor impairment in early Parkinson's disease: Feasibility study of an at-home testing device.

We tested the feasibility of a computer based at‐home testing device (AHTD) in early‐stage, unmedicated Parkinsons disease (PD) patients over 6 months. We measured compliance, technical reliability, and patient satisfaction to weekly assessments of tremor, small and large muscle bradykinesia, speech, reaction/movement times, and complex motor control. relative to the UPDRS motor score. The AHTD is a 6.5″ × 10″ computerized assessment battery. Data are stored on a USB memory stick and sent by internet to a central data repository as encrypted data packets. Although not designed or powered to measure change, the study collected data to observe patterns relative to UPDRS motor scores. Fifty‐two PD patients enrolled, and 50 completed the 6 month trial, 48 remaining without medication. Patients complied with 90.6% of weekly 30‐minute assessments, and 98.5% of data packets were successfully transmitted and decrypted. On a 100‐point scale, patient satisfaction with the program at study end was 87.2 (range: 80–100). UPDRS motor scores significantly worsened over 6 months, and trends for worsening over time occurred for alternating finger taps (P = 0.08), tremor (P = 0.06) and speech (P = 0.11). Change in tremor was a significant predictor of change in UPDRS (P = 0.047) and was detected in the first month of the study. This new computer‐based technology offers a feasible format for assessing PD‐related impairment from home. The high patient compliance and satisfaction suggest the feasibility of its incorporation into larger clinical trials, especially when travel is difficult and early changes or frequent data collection are considered important to document.

Pramipexole in routine clinical practice: a prospective observational trial in Parkinson's disease.

AbstractObjective: The mixed dopamine D2/D3 receptor agonist pramipexole is effective as monotherapy in early Parkinson’s disease and as adjunctive therapy in advanced disease. Clinical trials suggest that the benefits of pramipexole may extend beyond the relief of motor symptoms (akinesia, rigidity and tremor at rest) to amelioration of depressive symptoms in Parkinson’s disease. The aim of this study was to confirm the beneficial effects of pramipexole on the core symptoms of Parkinson’s disease (with a focus on tremor), as well as to assess its antidepressant activity, during routine clinical practice. The study also aimed to demonstrate the practicability of the Snaith-Hamilton Pleasure Scale (SHAPS-D), the Tremor Impact Scale (TIS) and the Short Parkinson’s Evaluation Scale (SPES) under conditions of routine clinical practice. Study design: This was a prospective observational study. Patients: Data for 657 outpatients with Parkinson’s disease were collected from German hospitals and specialist practices. The majority of patients were in Hoehn & Yahr stage II or III and were receiving levodopa. Methods: Pramipexole (Sifrol®) was initiated at a dosage of 0.375 mg/day (using a three-times-daily schedule) and titrated upwards, as required, at weekly intervals over a 4-week period to a maximum dosage of 4.5 mg/day (three times daily). Clinical evaluation was performed at baseline, at the end of the titration phase and at the end of maintenance therapy. Patients were assessed via the German questionnaire versions of the physician-assessed SPES, the self-evaluated TIS and the SHAPS-D. Changes in scale scores were evaluated nonparametrically, using the Wilcoxon-matched pairs test. Crombach’s α was used as a measure for item consistency. Results: Pramipexole significantly improved SPES subscores for motor symptoms, complications of therapy, psychological status and activities of daily living. Pramipexole also reduced the detrimental effect of tremor on activities of daily living and social interactions, as assessed by patients via the TIS. As indicated by the results of the SHAPS-D questionnaire, pramipexole significantly reduced anhedonia in patients who had associated depression. Internal consistency of SPES subscales was found to be unaltered between the initial evaluation and follow-up. Likewise, internal consistency for TIS and SHAPS-D was demonstrated. Pramipexole was well tolerated and accepted by the vast majority of physicians and patients. Conclusion: In addition to ameliorating the core symptoms of akinesia and rigidity in Parkinson’s disease, pramipexole improves tremor and depressive symptoms in routine clinical practice. The SPES, TIS and SHAPS-D were found to be useful instruments with validity in this study.

Autonomic nervous system function in Huntington's disease

Objective: To investigate whether Huntingtons disease (HD) affects autonomic nervous system (ANS) functioning. Methods: Twenty patients with HD who had positive genetic test results underwent standardised ANS function tests including sympathetic skin responses (SSRs) of the hands and feet, measurements of heart rate variability (HRV), both during five minutes of resting and deep respiration, and an orthostatic blood pressure test. Patients were classified according to the motor subscale of the unified Huntingtons disease rating scale (UHDRS; mean (SD) score 26.4 (13.6)) and divided into two subgroups: UHDRS <25 points (early stages, E-HD) and UHDRS ≥25 points (mid stages, M-HD). Autonomic indices were compared with those obtained for a group of well matched healthy controls (n=60). Results: Overall, patients showed lower HRV indices than controls. Multivariate analysis with the independent factor of “group” (controls, E-HD, M-HD) showed a significant group effect on both the high frequency power (F=4.32, p=0.017) and the coefficient of variation (F=4.23, p=0.018), indicating a significant reduction in vagal modulation in the M-HD group. There was a shift in autonomic neurocardiac balance towards sympathetic predominance in the M-HD group compared with controls (F=2.89, p=0.062). Moreover, we found an inverse correlation between the severity of clinical HD symptoms (assessed by the UHDRS) and the modulation of cardiovagal activity (p=0.028). Vagal dysregulation was present in two patients; one of them also showed a pathological blood pressure test and a latency prolongation in the SSRs of the hands. Two other patients had pathologically reduced SSR amplitudes. Only patients of the M-HD group were affected. Conclusion: Autonomic dysfunction is present even in the middle stages of HD and affects both the sympathetic and parasympathetic branch of the ANS.

ASK1 and MAP2K6 as modifiers of age at onset in Huntington’s disease

Huntington’s disease (HD) is an autosomal dominantly inherited neurodegenerative disease associated with abnormal expansions of a stretch of perfect CAG repeats in the HD gene. The number of repeat units is predictive for the age at onset (AO) of neurological symptoms. Part of the remaining variation in AO is attributed to modifier genes. In this study, genes involved in apoptosis were investigated as candidates for modulating AO in HD. A panel of 304 candidate genes was screened for allelic associations with motor AO via linked micro-satellite markers by pooling the DNAs of HD individuals from opposite ends of the AO distribution. After genotyping promising markers from the pooling experiment individually, markers revealed consolidated evidence for association in a candidate region comprising the genes MAP3K5 (ASK1)/PEX7 at 6q23.3 and in the gene MAP2K6 at 17q24.3. Fine-mapping of these candidate regions in a cohort of 250 Caucasian HD patients using single nucleotide polymorphism (SNP) markers delimitated the precise locations of association. Certain variations in an ASK1–PEX7 haplotype block explain 2.6% of additional variance in AO in our HD cohort. In males, 4.9% additional variance could be attributed to MAP2K6 genotype variations. Altogether, ASK1–PEX7 haplotypes and MAP2K2 genotype variations explain 6.3% additional variance in AO for HD. We hypothesise that sequence variations of ASK1 and MAP2K6 lead to partially sex-specific changes in the levels and/or phosphorylation states of p38 and p38-regulated proteins that might contribute to the observed delaying effects in the AO of HD.

Huntington's disease as caused by 34 CAG repeats

Huntingtons disease (HD) is an autosomal dominantly inherited neurodegenerative disorder caused by an abnormal expansion of a polymorphic stretch of CAG repeats in the coding 5′ part of the HD gene on chromosome 4p. Expansions of CAG blocks beyond 35 repeats are associated with the clinical presentation of HD. There is an intermediate range of rare alleles between 27 and 35 CAG repeats with a higher risk for further expansion in subsequent generations. Here, we report a 75‐year‐old male with clinical features of HD and 34 CAG repeat units.

Cardiomyopathy in Friedreich's ataxia‐assessment by cardiac MRI

Cardiomyopathy is an important and frequently life limiting manifestation of Friedreichs ataxia (FA), the most prevalent form of autosomal recessive ataxia. Left ventricular mass is used as primary outcome measure in recent intervention studies but systematic analyses of FA cardiomyopathy are sparse. To assess cardiac hypertrophy by cardiac magnetic resonance imaging (MRI) in vivo, we assessed 41 adult patients with genetically confirmed FA and 33 age‐ and sex‐matched healthy controls by cardiac MRI and echocardiogarphy. Septal hypertrophy and left ventricular mass index were determined by two independent raters. MRI revealed hypertrophy of the interventricular septum in 40% and increased left ventricular mass index in 29% of patients. Interobserver variability was less than 5% for both measures. GAA repeat length had only minor influence on interventricular septum thickness. Left ventricular mass index decreased with age. Severity of ataxia did not correlate with cardiac disease. In echocardiography wall diameter was assessable only in 31 of 41 FA patients with 32% of patients presenting septal hypertrophy and 6% increased left ventricular mass index. We conclude that cardiac hypertrophy is present only in a minority of adult FA patients. If despite this limitation intervention studies use left ventricular mass as outcome measure, MRI is recommended as the most accurate assessment of cardiac anatomy in vivo.

Dose-dependent improvement of myoclonic hyperkinesia due to Valproic acid in eight Huntington's Disease patients: a case series

BackgroundChorea in Huntingtons Disease (HD) is usually treated with antidopaminergic neuroleptics like haloperidol, olanzapine and tiaprid or dopamine depleting drugs like tetrabenazine. Some patients with hyperkinesia, however, react to treatment with antidopaminergic drugs by developing extrapyramidal side effects. In earlier studies valproic acid showed no beneficial effect on involuntary choreatic movements. Myoclonus is rare in HD and is often overseen or misdiagnosed as chorea.MethodsIn this report, we present eight patients whose main symptom is myoclonic hyperkinesia. All patients were treated with valproic acid and scored by using the Unified Huntingtons Disease Rating Scale (UHDRS) motor score before and after treatment. In addition to this, two patients agreed to be videotaped.ResultsIn seven patients myoclonus and, therefore the UHDRS motor score improved in a dose dependent manner. In three of these patients antidopaminergic medication could be reduced.ConclusionIn the rare subgroup of HD patients suffering from myoclonic hyperkinesia, valproic acid is a possible alternative treatment.