Incidence of Mild Cognitive Impairment: A Systematic Review

BACKGROUND/AIMS: Subjects with mild cognitive impairment (MCI) constitute a risk population of developing dementia and thus a population of clinical interest. This study reviews recent work on the incidence of MCI in the elderly. METHODS: Incidence papers were identified by a systematic literature search. Studies on the incidence of MCI were considered if they identified 'cognitively mildly impaired' subjects by application of the MCI criteria, used the 'person-years-at-risk' method, and were based on population- or community-based samples. RESULTS: Nine studies were identified. The incidence of amnestic MCI subtypes ranged between 9.9 and 40.6 per 1,000 person-years, and the incidence of non-amnestic MCI subtypes was 28 and 36.3 per 1,000 person-years. Regarding any MCI, incidence rates of 51 and 76.8 per 1,000 person-years were found. A higher risk of incident MCI mainly resulted for higher age, lower education and hypertension. DISCUSSION: The incidence rates of MCI varied widely, and possible risk factors for incident MCI were analysed only to a limited extent. The findings call for an agreement concerning the criteria used for MCI and the operationalisation of these criteria.