Objectives Mild Cognitive Impairment (MCI) constitutes a pre-stage of dementia in many cases. The aims of the present study were to estimate age- and gender-specific incidence of MCI and to identify risk factors for incident MCI in a population-based sample of cognitively healthy subjects aged 75 years and older.

Methods Data were derived from the Leipzig Longitudinal Study of the Aged (LEILA75+), a population-based study of individuals aged 75 years and older. Incidence was calculated according to the ‘person-years-at-risk’ method. Cox proportional hazards models were used to identify risk factors for incident MCI.

Results During the 8-year follow-up period, roughly one fourth (n=137; 26.4%) of the population at risk developed MCI. The overall incidence of MCI for subjects aged 75 years and older was 76.5 (95% PCI 64.7 to 90.4) per 1,000 person-years (overall person-years =1791.08). The incidence rate was highest in age group 85+ years and higher in women than men (80.8, 95% PCI 66.6 to 98.0 vs 65.8, 95% PCI 47.0 to 92.1). Cox proportional hazards model identified older age, subjective memory complaints, impairment in instrumental activities of daily living, and lower cognitive performance as significant risk factors for incident MCI.

Conclusions MCI has high incidence in the elderly population. The inclusion of restrictions in instrumental activities of daily living in the criteria of MCI particularly might be useful to improve the prediction of dementia. Subjective memory complaints in previously cognitively healthy individuals should be taken seriously as a possible pre-stage of MCI.