The inflammatory marker GDF-15 is not independently associated with late-life depression

• Serum GDF-15 levels were studied in patients with late-life depression in a large naturalistic cross sectional cohort study
• Average GDF-15 levels were increased in the 350 patients compared to the 128 controls
• Life-style was a crucial confounder for this increase, whereas factors as age, gender, cardiovascular comorbidity, were not

ObjectivesGrowth differentiation factor-15 (GDF-15) is an inflammatory molecule that reacts to cell stress. Since major depression is associated with inflammation, we examined whether GDF-15 levels are elevated in patients with late-life depression.MethodsPlasma GDF-15 levels were analyzed in 350 patients diagnosed with major depressive disorder in the last six months and 128 non-depressed controls from the Netherlands Study of Depression in Older persons (age ≥ 60 years). Major depressive disorder and age of onset were assessed with the Composite International Diagnostic Interview. Severity of depressive symptoms was measured with the Inventory of Depressive Symptoms (IDS-30). Multiple linear regression models were applied to study depression (diagnosis, onset age, severity, antidepressant drug use) as determinant of GDF-15 level, adjusted for demographic and clinical variables.ResultsPlasma GDF-15 levels were 22% higher in patients with major depression compared to controls. Within the depressed group, levels were higher in patients with older age of onset. GDF-15 levels showed a small, positive correlation to the levels of the inflammatory mediators IL-6 and C-reactive protein (r = 0.23, and 0.24, p < 0.05). This increase was independent from comorbidities, such as cardiovascular disease, rheumatism and diabetes, and anti-inflammatory drugs. However, this increase was dependent on lifestyle factors as smoking, physical activity and alcohol use. Within the depressed subgroup, neither depression severity or antidepressant drug use was associated with GDF-15 levels in the fully adjusted models.ConclusionThe inflammatory factor GDF-15 does not seem to be an independent inflammatory marker for late-life major depressive disorder.