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.