Apathy Mediates Cognitive Difficulties in Geriatric Depression

Abstract

Objective: Cognitive impairment associated with late-life depression can persist after remission of mood symptoms. Apathy, a common symptom of late-life depression, often leads to worse clinical outcomes. We examined if severity of apathy mediates cognitive difficulties in a cohort of older adults with major depression.

Methods: One hundred thirty-eight older adults with depression (54.4% female; mean [SD] age: 69.7 [7.4] years; mean [SD] education:15.6 [2.7] years) were recruited to participate in a treatment study, and only baseline data were analyzed. All participants received a comprehensive evaluation of depression, apathy, and cognition. We examined whether apathy mediated the relationship between depression and cognition, focusing our attention on memory and cognitive control. We then explored whether the mediation effects differed across women and men.

Results: Increased apathy was significantly associated with worse depression and lower performance in the cognitive control domain but not in memory. Higher depressive scores were significantly associated with worse cognitive control but not memory. Mediation analyses revealed a significant indirect effect on cognitive control by depression through increased apathy scores with the mediator accounting for 21% of the total effect. Stratifying by sex, we found that women exhibited a significant indirect effect, with the mediator accounting for 47% of the total effect, whereas there was no mediation by apathy in men.

Conclusions: The findings imply that increased apathy mediates the relationship between cognition and depression. The identification of mediating effects may inform future treatment strategies and preventive interventions that can focus on decreasing apathy to improve cognition in late-life depression.

Keywords: Apathy; cognition; late life depression; sex differences.

Figure 1

Mediation Model. The a-path represents the association between depression (HDRS-24) scores and apathy. The b-path denotes the relationship between apathy and cognitive scores, while also controlling for depression. The c-path and the c’-path represent the associations between HDRS-24 and cognitive scores without and with apathy included as a mediator, respectively. Age, sex, educational level used as covariates in all analyses.