VISUAL-ATTENTION AND PERCEPTION IN PATIENTS WITH HUNTINGTONS-DISEASE - COMPARISONS WITH OTHER SUBCORTICAL AND CORTICAL DEMENTIAS

Shifts in attention were examined in patients with Huntington's diseas e (HD) using a divided attention paradigm that involved the presentati on of global-local stimuli. The HD patients' pattern of performance wa s compared to the previously reported results of groups of patients wi th Alzheimer's disease (AD; Filoteo et al., 1992) or Parkinson's disea se (PD; Filoteo et al., 1994). Across consecutive trials of the divide d attention task, a visual target could appear at either the same glob al-local level or at a different level. When the tar et changed levels across consecutive trials, the AD patients demonstrated an impairment in disengaging attention from the level at which the last target appe ared, whereas the PD patients were impaired in maintaining their atten tion at the previously attended level. In contrast to these patterns o f performances, the HD patients did not demonstrate a significant impa irment in shifting attention between hierarchical levels. Both the AD and the PD patients' abnormal shifting ability was significantly relat ed to the number of errors they made in identifying target stimuli; ho wever, the pattern of the relationship was qualitatively distinct. The se results suggest that different attentional mechanisms may underlie AD and PD patients' visual-perceptual deficits. The HD patients' shift ing ability was not related to the number of errors they made in ident ifying target stimuli, suggesting that a different mechanism may accou nt for the visual-perceptual impairments exhibited by these patients.