Incidence of Mild Cognitive Impairment – A systematic review

Background: 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 incidence of MCI were considered if they identified 'cognitively mild impaired' subjects by application of the MCI criteria, used the 'person-years-at-risk' method, and were based on population-based or community-based samples. Results: Nine studies were identified. Incidence of Amnestic MCI subtypes ranged between 9.9 and 40.6 per 1,000 person-years, and incidence of Non-amnestic MCI subtypes was found to be 28 and 36.3 per 1,000 person-years. Regarding any MCI, incidence rates of 51 and 76.8 per 1,000 person-years have been found. A higher risk of incident MCI mainly was found for higher age, lower education and hypertension. Discussion: Incidence rates of MCI varied widely, and possible risk factors for incident MCI were analysed only to a limited extent. Findings call for an agreement concerning the criteria used for MCI and the operationalisation of these criteria.