Objective: To estimate rates of progression from mild cognitive impairment (MCI) to dementia and of reversion from MCI to being cognitively normal (CN) in a population-based cohort. Methods: Participants (n 5 534, aged 70 years and older) enrolled in the prospective Mayo Clinic Study of Aging were evaluated at baseline and every 15 months to identify incident MCI or dementia. Results: Over a median follow-up of 5.1 years, 153 of 534 participants (28.7%) with prevalent or incident MCI progressed to dementia (71.3 per 1,000 person-years). The cumulative incidence of dementia was 5.4% at 1 year, 16.1% at 2, 23.4% at 3, 31.1% at 4, and 42.5%at 5 years. The risk of dementia was elevated in MCI cases (hazard ratio [HR] 23.2, p , 0.001) compared with CN subjects. Thirty-eight percent (n 5 201) of MCI participants reverted to CN (175.0/1,000 person-years), but 65% subsequently developed MCI or dementia; the HR was 6.6 (p , 0.001) compared with CN subjects. The risk of reversion was reduced in subjects with an APOE e4 allele (HR 0.53, p , 0.001), higher Clinical Dementia Rating Scale-Sum of Boxes (HR 0.56, p , 0.001), and poorer cognitive function (HR 0.56, p , 0.001). The risk was also reduced in subjects with amnestic MCI (HR 0.70, p 5 0.02) and multidomain MCI (HR 0.61, p 5 0.003). Conclusions: MCI cases, including thosewho revert to CN, have a high risk of progressing to dementia. This suggests that diagnosis of MCI at any time has prognostic value.
ASJC Scopus subject areas
- Clinical Neurology
- Arts and Humanities (miscellaneous)