The relationship between impairment of voluntary movements and cognitive impairment in Huntington's disease.

The relationship between motor symptoms and cognitive impairment in Huntington's disease (HD) is still discussed. We analysed 45 HD patients in various stages using Unified Huntington's Disease Rating Scale motor subscale (voluntary and involuntary components were evaluated separately), verbal memory and executive functions tests. Partial correlations controlling for HD duration and age were used to estimate the relationships among factor scores for motor and cognitive impairment. Voluntary components of motor performance were found to be significantly correlated with verbal short-term memory disturbances (r = -0.361, P = 0.03), with tests of executive functions more dependent on motor performance (r = 0.640, P < 0.01) and also with tests of executive functions less dependent on motor performance (r = 0.461, P < 0.01). Involuntary components did not correlate significantly with any part of cognitive performance.