Association Between Self- and Proxy-Reported Depression and Quality of Life in Mild-Moderate Alzheimer's Disease

Abstract

Objective: Prior studies have reported an association between depression and quality of life (QOL) in Alzheimer's disease (AD), but the effect of self- versus proxy rating of mood and QOL has not been described.

Design: In this secondary analysis of data from a cohort study, the authors used a linear mixed-effects model to determine if the association between depression and QOL is affected by whether both measures are assessed by the same member of the patient-caregiver dyad.

Setting: Participants and caregiver informants were recruited from 10 California Alzheimer Disease Centers.

Participants: A total of 137 participants with mild-to-moderate Alzheimer's disease and their caregivers.

Measurements: Self- and proxy-rated scores on both the Geriatric Depression Scale (GDS) and the Quality of Life in Alzheimer's Disease scale (QoL-AD). Multivariable linear mixed-effects models were used to estimate the association between depression and QOL.

Results: Results of the multivariable linear mixed-effects models showed a significant association between self-rated QoL-AD and self-rated (B = -0.49, p <0.0001) but not proxy-rated GDS (B = -0.07, p = 0.19) after adjusting for confounders. Likewise, there was a significant association between proxy-rated QoL-AD and proxy-rated GDS (B = -0.48, p <0.0001) but not self-rated GDS (B = 0.05, p = 0.36).

Conclusion: Depression was associated with QOL in AD over short-term longitudinal follow-up, but the association was not statistically significant if both instruments are not administered to the same member of the patient-caregiver dyad. The choice of self- versus proxy-reported QOL should be intentionally considered in future studies as it may influence reported outcomes.

Keywords: Alzheimer's disease; Depression; dementia; quality of life.