Longitudinal evaluation of neuropsychiatric symptoms in Huntington's disease.

A group of 111 patients with Huntington's disease (HD) underwent a minimum of three annual neuropsychiatric assessments, using the Problem Behaviors Assessment for Huntington's Disease (PBA-HD). Longitudinal prevalence of neuropsychiatric symptoms was notably higher than baseline prevalence, suggesting that previous studies may have underestimated the extent of this clinical problem. Moreover, apathy, irritability, and depression were each associated with distinct longitudinal profiles. Apathy progressed over time and across disease stages. Irritability also increased significantly, but only in early stages of HD. Depression did not increase significantly at any stage of disease. The neuropsychiatric syndrome of apathy appears to be intrinsic to the evolution and progression of HD.

Automaticity and attention in Huntington's disease: when two hands are not better than one.

People with Huntington's disease (HD) commonly report difficulty carrying out two everyday tasks simultaneously. This difficulty, confirmed by experimental studies, is typically ascribed to impaired attention. Yet, dual-task problems extend to relatively simple tasks, such as walking and talking, which would ordinarily be considered relatively undemanding of attention. The study tests the hypothesis that in HD there is a deficit in the ability to automatise task performance. Thus, simple tasks, which place minimal demands on conscious attention in healthy controls, make disproportionately high demands on attentional resources in HD. We examined the performance of HD patients and healthy controls on a simple, paced finger-tapping task, comparing single-task (tapping with one hand) and dual-task (tapping with both hands simultaneously) performance. For HD patients, bimanual tapping increased the task demands: there was greater variability in tapping rate and patients reported that the 'dual-task' condition was more difficult. The opposite pattern was observed for controls. Variability in tapping performance in HD was highly correlated with performance on cognitive tasks that have the potential to be automatized but not with performance on tasks that are more demanding of executive control, suggesting a common substrate for cognitive and motor automaticity. The data support the hypothesis that HD patients are impaired in their capacity for automisation, and suggest that impaired automaticity may be one source of attentional deficits in HD. The findings have implications for the interpretation of 'high level' deficits in attention and executive function previously reported in HD.