INITIATION AND EXECUTION OF MOVEMENT SEQUENCES IN THOSE SUFFERING FROM AND AT-RISK OF DEVELOPING HUNTINGTONS-DISEASE

Recent research has shown that Huntington's disease (HD) causes proble ms in the initiation and execution of movement (akinesia, bradykinesia ): information which is useful in documenting the functional progressi on of the disease. The present experiment used a sequential movement t ask to characterize such impairments. Eighteen patients diagnosed as s uffering from HD, and a similar number of matched At-Risk (AR) and Nor mal control subjects, performed sequential button pressing tasks, unde r varying amounts of visual advance information. Specific dimensions o f motor control were examined (hand, direction). Movement initiation a nd in particular movement duration were useful indicators of the funct ional progression of the disease, and also detected anomalies of perfo rmance in some AR individuals. Impaired motor programming was indicate d by patients' difficulty in initiating movements in the absence of ex ternal visual cues, and their problems in utilizing advance informatio n to control movement. Patients had specific deficits in initiating mo vements with the nonpreferred hand, and directional movement asymmetri es were accentuated. The results suggest that HD causes difficulties a t three discrete levels: in utilizing advance information, in the init iation and in the spatial representation of movement.