A preclinical phase in vascular dementia: cognitive impairment three years before diagnosis

Abstract

Alzheimer's disease (AD) and vascular dementia (VaD) patients exhibit similar patterns of deficits in many cognitive tasks in the early clinical stages. Considering that preclinical cognitive deficits are well documented in AD, the purpose of the present study was to investigate if such deficits are also present in VaD. The cognitive outcome measure was the Mini-Mental State Examination (MMSE). The sample was taken from a population-based study and consisted of 699 persons who were nondemented at baseline, but out of whom 35 persons were diagnosed with VaD and 170 with AD at a 3-year follow-up. Both the incident VaD and AD cases exhibited baseline deficits on the total score of the MMSE and three of the subscales: orientation to time, orientation to place, and delayed memory. Further, both dementia groups exhibited precipitous decline on most MMSE subscales during the 3-year follow-up period. Logistic regression analyses showed that all subscales that revealed deficits at baseline predicted dementia status at follow-up. Delayed memory was the best predictor in both preclinical VaD and preclinical AD. Thus, these results demonstrate preclinical cognitive deficits in VaD in a measure of global cognitive functioning, which closely resemble those observed in AD. This observation suggests that circulatory disturbance is associated with cognitive problems several years before the actual VaD diagnosis.