Visual hallucinations and altered visual information processing in Parkinson dis

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Visual hallucinations and altered visual information processing in Parkinson

disease and dementia with Lewy bodies

8 Jan 2010

Abstract

Visual hallucinations (VHs) are common in dementia with Lewy bodies (DLB) and

Parkinson's disease with dementia (PDD), while auditory hallucinations are rare.

To neurophysiologically investigate the pathophysiology of VHs in these

disorders, we studied event-related potentials (ERPs) of DLB, PDD, and

Alzheimer's disease (AD) patients. We compared visual and auditory ERP latencies

among PDD patients with and without VHs (PDD-H: 11, PDD-N: 6), DLB patients

(24), and AD patients (21). To elicit visual and auditory ERPs, a facial

discrimination paradigm and a conventional auditory odd-ball paradigm,

respectively, were used. The mean visual P3 latencies in the PDD-H and DLB

groups were significantly longer than that in the AD group, while the mean

auditory P3 latencies in all four patient groups were comparable. The mean

visual P2 latencies in the PDD-N, PDD-H, and DLB groups were significantly

longer than that in the control group. Our findings suggest that visual

cognitive functions are selectively impaired in hallucinatory patients with DLB

and PDD. VHs may be associated in part with predominant visual cognitive

impairments attributable to PDD and DLB pathologies. Our findings also suggest

that the impairments occur at the early stage of facial information processing.

© 2009 Movement Disorder Society

http://tinyurl.com/yg3jten