Abstract
BACKGROUND: The Mini-Mental State Examination (MMSE) is commonly used in clinical and research settings to assess cognitive function and scores 27-30 are considered normal. Whether individuals with lower MMSE scores within this normal range are at increased risk for Alzheimer's disease and related dementias (ADRD) remains unclear. We sought to examine this question in the current study. METHODS: In the Cardiovascular Health Study (CHS), 4433 community-dwelling adults ≥ 65 years had MMSE 27-30: MMSE-30 (n = 1228), MMSE-29 (n = 1353), MMSE-28 (n = 1079) and MMSE-27 (n = 773). HR (95% CI) for incident ADRD during 23 years of follow-up associated with MMSE-29, MMSE-28, and MMSE-27 were estimated, adjusting for 27 baseline characteristics including activities of daily living (ADL) impairment. ADRD was defined using International Classification of Diseases (ICD) codes. RESULTS: Individuals with MMSE-30, MMSE-29, MMSE-28, and MMSE-27 had mean ages of 71.1, 71.9, 72.6, and 73.4 years, and mean ADL impairment scores of 0.06, 0.08, 0.12 and 0.16, respectively (both p < 0.001). Overall, 59% were women and 10% African American. ADRD occurred in 8.5%, 11.4%, 12.5% and 13.6% of those with MMSE-30, MMSE-29, MMSE-28, and MMSE-27, respectively. Compared with MMSE-30, HR (95% CI) for incident ADRD for MMSE-29, MMSE-28, and MMSE-27 were 1.48 (1.16-1.90), 1.82 (1.42-2.35) and 2.15 (1.64-2.82), respectively. These associations varied by age, sex, race, education, and self-reported general health. CONCLUSIONS: These findings suggest that among community-dwelling older adults with normal MMSE, lower scores were associated with impaired ADL and significant, independent, and incrementally higher risk of ADRD.