The role of metabolic syndrome in late-life depression over 6 years: The NESDO study.

Background: Metabolic syndrome (MetS) has been associated with both early- and late-life depression. This study investigated whether baseline MetS and its individual components are associated with the course of depression over six years among older persons with a formal depression diagnosis.

Methods: Data were used from 378 older persons with a depressive disorder from the Netherlands Study of Depression in Old age (NESDO) with a 6-year follow-up. A formal depression diagnosis according to DSM-IV-TR criteria was ascertained with the Composite International Diagnostic Interview. Severity of depressive symptoms was assessed with the Inventory of Depressive Symptomatology at 6-month intervals. Metabolic syndrome (MetS) was defined according the modified National Cholesterol Education Programme - Adult Treatment Panel III criteria. Primary outcome was time to remission from depression. We applied cox regression analysis for the primary outcome and linear mixed models for secondary analyses.

Results: Neither MetS nor its individual components were associated with time to remission from depression (MetS: HR = 1.03; 95% CI = 0.74 - 1.44; p = 0.85), or with depression severity (MetS: B = 0.02; SE = 0.04; p = 0.64) and course of depressive symptoms (MetS: B = -0.01; SE = 0.01; p = 0.23) over 6-years follow-up.

Limitations: Attrition was relatively high (46.8%). Furthermore, we only had information on formal depression diagnosis at baseline, 2-year, and 6-year follow-up.

Conclusions: We found no evidence for an effect of baseline presence of metabolic dysregulation on the course of formally diagnosed depression in older persons. Metabolic syndrome in depressed patients should be clinically monitored for other reasons than predicting chronicity or severity of depression.