Vascular risk factors, incidence of MCI, and rates of progression to dementia.

OBJECTIVE: To estimate prevalence, incidence, and rate of progression of mild cognitive impairment (MCI) to dementia and correlated vascular risk factors with incident MCI and its progression to dementia. METHODS: The authors evaluated 2,963 individuals from the population-based sample of 5,632 subjects 65 to 84 years old, at the first (1992 to 1993) and second survey (1995 to 1996) of the Italian Longitudinal Study on Aging (ILSA), with a 3.5-year follow-up. Dementia, Alzheimer disease (AD), vascular dementia (VaD), other types of dementia, and MCI were classified using current clinical criteria. RESULTS: Among the 2,963 participants, 139 MCI patients were diagnosed at the first ILSA survey. During the 3.5-year follow-up, 113 new events of MCI were diagnosed with an estimated incidence rate of 21.5 per 1,000 person-years. We found a progression rate to dementia (all causes) of 3.8/100 person-years. Specific progression rates for AD, VaD, and other types of dementia were 2.3, 1.3, and 0.3/100 person-years. Furthermore, age was a risk factor for incident MCI (RR: 5.93, 95% CI: 3.17 to 11.10), while education was protective (RR: 0.06, 95% CI: 0.03 to 0.10), and serum total cholesterol evidenced a borderline nonsignificant trend for a protective effect. There was a nonsignificant trend for stroke as a risk factor of progression of MCI to dementia. CONCLUSIONS: In this population, among those who progressed to dementia, 60% progressed to AD and 33% to VaD. Vascular risk factors influence incident mild cognitive impairment and the rate of progression to dementia.