Health-related Quality of Life, Cognitive Performance, and Incident Dementia in a Community-based Elderly Cohort

Background: We hypothesized that higher quality of life would be associated with better cognitive function and a reduced risk of incident all cause dementia and Alzheimer disease (AD) in older adults. Materials and Methods: Participants included 1183 older adults with an average age of 78.2 (SD=5.3) from Einstein Aging Study. The 36-Item Short-Form Health Survey was used to measure health-related quality of life (HRQoL). We investigated baseline associations between the cognitive domains of memory, executive function, and general fluid ability with 8 subscales of the 36-Item Short-Form Health Survey (physical functioning, role limitations due to physical problems, bodily pain, general health perceptions, social functioning, role limitations due to emotional problems, vitality, and general mental health) and the 2 component summary scores of physical component summary (PCS) and mental component summary (MCS). Next, we used Cox proportional hazard models to assess the predictive validity of HRQoL subscales for the onset of incident dementia and incident AD. Results: At baseline, higher scores (better HRQoL) on MCS and its 4 subscales (social functioning, role limitations due to emotional problems, vitality, and general mental health) were associated with higher performance on both memory and executive function domains. Higher scores in role limitation due to physical problems, role limitation due to emotional problems, and general mental health subscales were associated with reduced risk of incident dementia. Higher MCS, but not PCS, predicted a reduced incident of all-cause dementia and AD. Conclusions: These findings suggest that diminution of HRQoL precedes the onset of diagnosable dementia and may be useful in the prediction of dementia onset.