Proximity to clinical onset influences motor and cognitive performance in presymptomatic Huntington disease gene carriers.

BACKGROUND: Neuroimaging studies of Huntington disease (HD) gene carriers have shown that characteristic striatal atrophy begins long before symptom onset, but findings regarding the presence of preclinical functional deficits are inconsistent.
OBJECTIVE: To further investigate potential motor and cognitive deficits in presymptomatic gene carriers (PSGCs), and relationships between performance and estimated proximity to HD symptom onset.
METHOD: PSGCs and age-matched controls performed motor tasks involving cued sequential button presses, and cognitive tasks involving simple and complex choice responses to visuospatial stimuli.
RESULTS: PSGCs demonstrated similar motor performance speed, and nonsignificantly slower cognitive reaction times, to controls. PSGCs made more errors than controls to stimuli requiring a spatially incongruent response, possibly suggesting some difficulty in inhibiting automatic responses. Movement times for motor conditions where little advance information was provided, and reaction times for low demand cognitive tasks, were positively correlated with PSGCs' estimated probability of symptom onset within 5 years.
CONCLUSIONS: Response speed was slower for those PSGCs estimated to have higher probabilities of close onset. These findings suggest that to provide improved knowledge of how HD begins, knowledge that may be used in clinical trials, future research should further explore relationships between function and proximity to onset.