Self-Rated Health As a Predictor of Incident Dementia in Older Adults with Cognitive Impairment, No Dementia (CIND)

Background and Purpose: Self-rated health (SRH), individuals’ subjective perception of their health, is frequently used to measure overall health status. SRH has been shown to predict subsequent mortality, morbidity, and a wide range of adverse health outcomes such as depression and functional decline among older adults. Thus, SRH is often incorporated into clinical practice and may be a good biomedical marker of overall health. Several studies indicated that SRH is a strong predictor of all types of dementia among older adults. To date, however, there is limited research exploring the association between SRH reported by those with cognitive impairment no dementia (CIND) and incident dementia. SRH could be different in older adults with CIND compared to SRH in those with normal cognition. This study aimed to examine whether SRH independently predicts incident dementia in older adults with CIND.

Methods: Data came from 1995 to 2014 wave of the Health and Retirement Study (HRS), a nationally representative longitudinal survey of noninstitutionalized individuals over the age of 50 (n=17,550). The status for the cognitive function was measured using the Telephone Interview for Cognitive Status (TICS). An overall cognitive score was calculated from summing up items of immediate and delayed word recall test, a serial 7s test, and a backwards counting test for a total of 27 points. Using the Langa-Weir classifications, CIND was defined as a score of 7 to 11 while dementia was defined as a score of 0 to 6. SRH was measured using a single question: “In general, how would you say your health: excellent, very good, good, fair or poor?”. For the purpose of this study, we dichotomized SRH into two categories: (excellent, very good, good) as good health and (fair to poor) as poor health. We used a cox proportional hazards model to estimate hazard ratios for incident dementia in relation to SRH.

Results: In a Cox proportional hazard model, SRH predicted dementia (adjusted hazard ratio: 1.38, 95% confidence interval [CI] = 1.01-1.89, p<0.05) among older adults without cognitive impairment or dementia. The risk of dementia was increased in respondents with poor or fair among older adults with normal cognition. However, SRH reported by older adults with CIND did not predict incident dementia (adjusted hazard ratio: 1.04, 95% CI = 0.88-1.23, p>0.05).

Conclusions and Implications: The finding highlights the potential role of the underlying effect of SRH on predicting dementia in older adults without CIND. However, the independent effect of SRH on predicting incident dementia in older adults with CIND was not significant. The responses obtained from older adults with CIND may not be fully reliable due to their limited cognitive function. Therefore, a cautious interpretation is needed since SRH may not be a useful factor in predicting dementia in people with CIND.