We investigated whether (1) cognitive deficits are present among
persons who will be diagnosed with vascular dementia (VaD) 3 years
later, and (2) the pattern of such deficits is similar to that observed
in preclinical Alzheimer's disease (AD). The VaD diagnosis was a
diagnosis of post-stroke dementia. Population-based samples of 15
incident VaD cases, 43 incident AD cases, and 149 normal controls were
compared on tests of episodic and short-term memory, verbal fluency,
and visuospatial skill. Both dementia groups showed preclinical
impairment relative controls on tasks assessing episodic memory 3 years
before diagnosis, and there were no differences between these groups on
any cognitive measure. The existence of a preclinical phase in the
present VaD cases suggests that circulatory disturbance may affect
cognitive performance before the occurrence of stroke that leads to
clinical VaD. These results extend previous findings of similar
patterns of cognitive deficits in the early clinical phases of AD and
VaD to the preclinical phases of these diseases. (JINS, 2004,
10, 382–391.)