Mild Cognitive Impairment and 10‐Year Trajectories of Disability in the Iowa Established Populations for Epidemiologic Studies of the Elderly Cohort

Abstract

To apply diagnostic criteria for mild cognitive impairment (MCI) to a geographically representative sample, to estimate the prevalence of MCI, and to estimate 10-year trajectories of incident disability for cognitively intact participants and subgroups with MCI. Prospective cohort; 10 years of follow-up. Community-based survey of noninstitutionalized population aged 65 and or older in two rural Iowa counties (Washington and Iowa). Iowa Established Populations for Epidemiologic Studies of the Elderly (aged > or = 65; N = 3,673; 61.3% female; 99.9% white). Age, sex, education, Short Portable Mental Status Questionnaire (SPMSQ), 20-item word recall, activities of daily living (ADLs), instrumental activities of daily living (IADLs), chronic medical conditions. MCI was prevalent in 24.7% of participants at baseline. Most participants in the overall cohort remained stable or changed slowly (< or = 1 new limitations) over 10 years (63.1% for SPMSQ, 89.3% for word recall, and 61.7% for ADL disability). For MCI/no prevalent IADL disability (Stage 1 MCI), disability progression was similar to that in the cognitively intact subgroup (median = 0.08 vs 0.05 disabilities per year). For MCI plus prevalent IADL disability (Stage 2 MCI), the median rate of change was equivalent to that of the severely impaired (0.23 disabilities per year; interquartile range = 0.12-0.36). Unlike participants with MCI who reported no IADL limitations, those with such limitations were more likely to develop ADL disability--a prerequisite for a diagnosis of dementia.