Factors mediating the effects of a depression intervention on functional disability in older African Americans

Abstract

Objectives: To determine factors mediating the effects of a depression intervention for older African Americans on functional disability and, secondarily, whether functional improvements mediate intervention effects on depressive symptoms.

Design: Structural equation modeling to examine mediators in a secondary analysis of a randomized trial with 4-month follow-up.

Setting: Philadelphia region.

Participants: Community-dwelling African Americans (≥55) with depressive symptoms living in an urban area (N = 208).

Intervention: Up to 10 one-hour sessions over 4 months conducted by licensed social workers who provided care management, referrals and linkages, stress reduction techniques, depression knowledge and symptom recognition, and behavioral activation techniques.

Measurements: Main outcome was self-reported functional difficulty level for 18 basic activities. Mediators included depression severity (Patient Health Questionnaire), depression knowledge and symptom recognition, behavioral activation, and anxiety.

Results: At 4 months, the intervention had positive effects on functional difficulty and all mediators (P < .001). Separate structural equation models indicated that two factors (reduced depressive symptoms (23.5% mediated) and improved depression knowledge and symptom recognition (52.9% mediated)) significantly mediated the intervention's effect on functional disability. Enhancing behavioral activation and decreasing anxiety were not found to mediate improvements in functional disability. The two significant mediators jointly explained 62.5% of the intervention's total effect on functional disability. Functional improvement was not found to mediate the intervention's effect on depressive symptoms.

Conclusion: This multicomponent depression intervention for African Americans has an effect on functional disability that is driven primarily by enhancing symptom recognition and decreasing depressive symptoms. Reduction of functional difficulties did not account for improvements in depressive symptoms. Nonpharmacological treatments for depressive symptoms that enhance symptom recognition in older African Americans can also reduce their functional difficulties with daily living activities.

Trial registration: ClinicalTrials.gov NCT00511680.

Keywords: depression; functional disability; mediation analysis.

Figure 1

Two-wave mediation model used to examine mediators individually. BL = Baseline observation. Δ = 4-month score minus baseline score.

Figure 2

Multiple-mediator model of intervention effect on change in functional disability. BL = Baseline observation. Δ = 4-month score minus baseline score.