Cognitive scores, even within the normal range, predict death and institutionalization

Dementia is a predictor of death and institutionalization. It is less clear if variations in cognition within the normal range predict adverse outcomes.

To determine if variation at the high end of cognitive test scores predicts mortality or institutionalization, independent of the effect of potential confounders.

Secondary analysis of the Canadian Study of Health and Aging, a population-based longitudinal study with an initial data collection in 1991 and follow-up five years later.

Community-dwelling seniors living in Canada.

9008 consenting seniors were sampled from representative population registries in Canada.

Age, gender, marital status, the Mini-Mental State Examination, self-rated health, and activities of daily living.

Death or institutionalization over the five years of follow-up.

Mini-Mental State Examination scores predicted mortality and institutionalization. The unadjusted odds ratio of mortality was 0.85 (95% confidence interval 0.84, 0.86) per point on the Mini-Mental State Examination, and the adjusted odds ratio was 0.95 (95% confidence interval 0.93, 0.97). The unadjusted odds ratio for institutionalization was 0.83 (95% confidence interval 0.82, 0.85), and the adjusted odds ratio was 0.91 (95% confidence interval 0.90, 0.94). This effect was present even in analyses restricted to those within the normal range of Time 1 Mini-Mental State Examination scores.

Low normal cognitive test scores predict adverse outcomes. Clinicians should consider close clinical follow-up of those with low normal cognitive test scores. Further research is needed to target seniors for follow-up and possible intervention to decrease mortality and institutionalization risk.