Prevalence of Mild Cognitive Impairment and Its Subtypes Are Influenced by the Application of Diagnostic Criteria: Results from the Korean Longitudinal Study on Health and Aging (KLoSHA)

AIMS: We investigated the influence of varying applications of diagnostic criteria on the prevalence of mild cognitive impairment (MCI) in community-dwelling Korean elders. METHODS: A study population of 1,118 Korean elders was randomly sampled from the residents aged 65 years or older living in Seongnam, Korea. Standardized face-to-face interviews, with neurological and physical examinations, were conducted with 714 respondents. Cognitive function was evaluated using the Korean version of the CERAD Neuropsychological Assessment Battery, digit span test, and lexical fluency test. Activities of daily living were evaluated using the Blessed Dementia Scale in the CERAD Clinical Assessment Battery (Korean version). Using variable sets of operational diagnostic criteria, the prevalence of MCI was estimated. RESULTS: Age- and gender-standardized prevalence estimates according to the Petersen criteria were 28.6% (95% CI = 25.3-31.9) for overall MCI, 17.0% (95% CI = 14.3-19.8) for amnestic MCI, and 11.5% (95% CI = 9.2-13.9) for non-amnestic MCI. However, the estimated prevalence of MCI varied widely (8.3-27.6%) according to the applied operational diagnostic criteria. The proportion of MCI subtypes also varied considerably according to the number and types of applied neuropsychological tests. CONCLUSIONS: Variable implementation of MCI diagnostic criteria may significantly complicate the homogeneity of this condition.