Perception, attention, and working memory are disproportionately impaired in dementia with Lewy bodies compared with Alzheimer's disease
- aUniversity Department of Psychiatry, Addenbrooke's Hospital, Cambridge CB2 2QQ, UK, bUniversity Department of Neurology, cMRC Cognition and Brain Sciences Unit, 15 Chaucer Road, Cambridge CB2 2EF, UK, dPsychiatric Services for the Elderly, Fulbourn Hospital, Cambridge CB1 5EF, UK
- Professor J R Hodgesjohn.hodges{at}mrc-cbu.cam.ac.uk
- Received 10 November 1999
- Revised 26 July 2000
- Accepted 14 August 2000
Abstract
OBJECTIVE To test the hypotheses that visuoperceptual and attentional ability are disproportionately impaired in patients having dementia with Lewy Bodies (DLB) compared with Alzheimer's disease (AD).
METHODS A comprehensive battery of neuropsychological tasks designed to assess working, episodic, and semantic memory, and visuoperceptual and attentional functions was given to groups of patients with DLB (n=10) and AD (n=9), matched for age, education, and mini mental state examination (MMSE), and to normal controls (n=17).
RESULTS Both patient groups performed equally poorly on tests of episodic and semantic memory with the exception of immediate and delayed story recall, which was worse in the AD group. Digit span was by contrast spared in AD. The most striking differences were on tests of visuoperceptual/spatial ability and attention. Whereas patients with AD performed normally on several subtests of the visual object and space perception battery, the DLB group showed substantial impairments. In keeping with previous studies, the AD group showed deficits in selective attention and set shifting, but patients with DLB were more impaired on virtually every test of attention with deficits in sustained, selective, and divided attention.
CONCLUSIONS Patients with DLB have substantially greater impairment of attention, working memory, and visuoperceptual ability than patients with AD matched for overall dementia severity. Semantic memory seems to be equally affected in DLB and AD, unlike episodic memory, which is worse in AD. These findings may have relevance for our understanding of the genesis of visual hallucinations, and the differential diagnosis of AD and DLB.
