We investigated the prevalence of mild cognitive impairment (MCI) in Olmsted County, MN, using in-person evaluations and published criteria.
We evaluated an age- and sex-stratified random sample of Olmsted County residents who were 70–89 years old on October 1, 2004, using the Clinical Dementia Rating Scale, a neurologic evaluation, and neuropsychological testing to assess 4 cognitive domains: memory, executive function, language, and visuospatial skills. Information for each participant was reviewed by an adjudication panel and a diagnosis of normal cognition, MCI, or dementia was made using published criteria.
Among 1,969 subjects without dementia, 329 subjects had MCI, with a prevalence of 16.0% (95% confidence interval [CI] 14.4–17.5) for any MCI, 11.1% (95% CI 9.8–12.3) for amnestic MCI, and 4.9% (95% CI 4.0–5.8) for nonamnestic MCI. The prevalence of MCI increased with age and was higher in men. The prevalence odds ratio (OR) in men was 1.54 (95% CI 1.21–1.96; adjusted for age, education, and nonparticipation). The prevalence was also higher in subjects who never married and in subjects with an APOE ε3ε4 or ε4ε4 genotype. MCI prevalence decreased with increasing number of years of education (p for linear trend <0.0001).
Our study suggests that approximately 16% of elderly subjects free of dementia are affected by MCI, and amnestic MCI is the most common type. The higher prevalence of MCI in men may suggest that women transition from normal cognition directly to dementia at a later age but more abruptly.
= Alzheimer disease;
= amnestic mild cognitive impairment;
= Clinical Dementia Rating scale;
= confidence interval;
= Diagnostic and Statistical Manual of Mental Disorders, 4th edition;
= Functional Activities Questionnaire;
= mild cognitive impairment;
= nonamnestic mild cognitive impairment;
= odds ratio;
= Short Test of Mental Status;
= Telephone Interview for Cognitive Status-modified;
= Wechsler Adult Intelligence Scale-Revised.