Longitudinal relationships between depression and functioning in people with type 2 diabetes.

Background: The reciprocal relationship between depression and functioning in people with chronic conditions is poorly understood.

Purpose: The aim of the present study was to analyze the dynamic relationship between depression and functioning in a community sample of people with diabetes.

Methods: Participants with diabetes were assessed at baseline and three yearly follow-up assessments (n = 1,403). Depression was assessed using the Patient Health Questionnaire. Global functioning was assessed using the World Health Organization Disability Assessment Schedule II.

Results: Path analysis suggested a reciprocal relationship between depression and functioning. Baseline depression was associated with functioning at 3 years follow-up through depression and functioning at 1 and 2 years follow-up assessments.

Conclusions: Depression and functioning might interact with each other in a dynamic way: depression at one assessment point might predict poor functioning at the next assessment point, which in turn might predict depression at the next assessment point. This should be taken into account in both treatment and research programs.