Cognitive decline after entering a nursing home: a 22-year follow-up study of institutionalized and noninstitutionalized elderly people.

Objective: The objective of this study is to compare cognitive decline of elderly people after entering an institution with that of elders living in the community with similar clinical conditions.

Design: The Personnes Agées QUID (PAQUID) cohort is a prospective population-based study which included, at baseline, 3777 community-dwelling people aged 65 years and older. Participants were followed-up for 22 years. Among those who were nondemented and living at home at baseline, 2 groups were compared: participants who entered a nursing home during study follow-up (n = 558) and those who remained living at home (n = 3117). Cognitive decline was assessed with Mini-Mental State Examination (MMSE), Benton visual retention test, and verbal fluency Isaacs Set Test.

Results: After controlling for numerous potential confounders, including baseline MMSE and instrumental activities of daily living scores, incident dementia, depressive symptoms, and chronic diseases, nursing home placement was significantly associated with a lower score on MMSE between the last visit before and after institutionalization (difference of 2.8 points, P < .0001) and greater further cognitive decline after institutionalization (difference of 0.7 point per year, P < .0001). Similar results were found for the Benton memory test. In a second series of analysis in which the persons who became demented over the study follow-up were excluded, the results remained unchanged.

Conclusions: The present study suggests that institutionalized elderly people present a greater cognitive decline than persons remaining in the community. The reasons of that decline remain unclear and may be related to physical and psychological effects of institutionalization in elderly people.