Neuropsychological deficits are a main feature of Huntington's disease (HD) with previous data suggesting involvement of attentional functions. Attention can be divided into several different dimensions: intensity, selectivity and supervisory attentional control. These different aspects of attention were investigated in a group of 13 patients with HD and 13 healthy matched control subjects. HD patients were impaired mostly for the intensity dimension: contrary to controls, and like other neurological patient groups, they were not able to speed up their reaction times when an auditory warning stimulus preceded a visual target which suggests a deficit in 'extrinsic alertness.' In addition less severe impairments were found in the dimensions selectivity and supervisory attentional control.

The results suggest marked impairments of patients with HD in early visual sensory processing (early components). Deficits in visual search might be attributed to an impairment to deploy attentional resources across the visual field and/or an inability to control eye movements. The ERPs in the memory task differed grossly from similar data obtained by others in patients with Alzheimer disease, suggesting a different neural basis for the amnesia in HD.