Stratifying Risk for Cognitive Decline in Older Adult Populations using the Geriatric Depression Scale.

Objectives: Late-life psychological symptoms in older adults such as depression and apathy have been increasingly associated with increased risk of cognitive and functional decline. The goal of this study was to conduct a confirmatory factor analysis of the Geriatric Depression Scale (GDS), pooling 3 unique cohorts of older adults to 1) develop a novel measurement model that distinguishes apathy from other domains of depression including dysphoria and cognitive concern and 2) evaluate if the measurement model distinguishes older adult populations with varied risk for cognitive decline.

Methods: We pooled the baseline waves of three older adult cohorts (N=1421). With the aim of partitioning apathy from other constructs that compose the GDS and with a PCA suggesting 3-component solution, we then conducted a confirmatory factor analysis (CFA) using lavaan and less R.

Results: CFA yielded 3 factors: dysphoria, apathy, and cognitive concern. All the dysphoria, apathy, and cognitive concern factors showed acceptable unidimensionality with α=.76, .59, and .54, respectively. The Cognitive Risk Primary Care cohort had significantly higher mean dysphoria, apathy and cognitive concern scales.

Conclusions: This culturally, linguistically, and educationally diverse sample population yielded factors with acceptable reliability and good face validity. This strategy has resulted in a generalizable measurement model to identify people at risk for Alzheimer's disease and related dementia. In particular, the apathy scale score can be used to identify older adults at risk for cognitive and functional decline across research and clinical settings.