The Mini-Cog as a screen for dementia: validation in a population-based sample

OBJECTIVES: To test the Mini-Cog, a brief cognitive screening test, in an epidemiological study of dementia in older Americans. DESIGN: A population-based post hoc examination of the sensitivity and specificity of the Mini-Cog for detecting dementia in an existing data set. SETTING: The Monongahela Valley in Western Pennsylvania. PARTICIPANTS: A random sample of 1,119 older adults enrolled in the Monongahela Valley Independent Elders Survey (MoVIES). MEASUREMENTS: The effectiveness of the Mini-Cog in detecting independently diagnosed dementia was compared with that of the Mini-Mental State Examination (MMSE) and a standardized neuropsychological battery. RESULTS: The Mini-Cog, scored by an algorithm as "possibly impaired" or "probably normal," and the MMSE, at a cutpoint of 25, had similar sensitivity (76% vs 79%) and specificity (89% vs 88%) for dementia, comparable with that achieved using a conventional neuropsychological battery (75% sensitivity, 90% specificity). CONCLUSION: When applied post hoc to an existing population, the Mini-Cog was as effective in detecting dementia as longer screening and assessment instruments. Its brevity is a distinct advantage when the goal is to improve identification of older adults in a population who may be cognitively impaired. Prior evidence of good performance in a multiethnic community-based sample further supports its validity in the ethnolinguistically diverse populations of the United States in which widely used cognitive screens often fail.