Mild cognitive impairment: prevalence and incidence according to different diagnostic criteria

Abstract

Background Although mild cognitive impairment is associated with an increased risk of developing dementia, there has been little work on its incidence and prevalence. Aims To report age-specific prevalence, incidence and predictive validities for four diagnostic concepts of mild cognitive impairment. Method A community sample of 1045 dementia-free individuals aged 75 years and over was examined by neuropsychological testing in a three-wave longitudinal study. Results Prevalence rates ranged from 3% to 20%, depending on the concept applied. The annual incidence rates applying different case definitions varied from 8 to 77 per 1000 person-years. Rates of conversion to dementia over 2.6 years ranged from 23% to 47%. Conclusions Mild cognitive impairment is frequent in older people. Prevalence, incidence and predictive validities are highly dependent on the diagnostic criteria applied.