Inflammation in older subjects with early- and late-onset depression in the NESDO study: a cross-sectional and longitudinal case-only design

•Elevated systemic inflammatory activity is involved in the etiology of depression.•Whether the role of inflammation is different in late-onset depression is unknown.•Higher CRP levels are distinctive of late-onset compared to early-onset depression.•Whole blood LPS stimulated cytokine levels are similar between late-onset and early-onset depression.•IL-6 levels are predictive of a slower decline of depression severity in late-life. Different biological mechanisms may underlie depression beginning in early life (early-onset) and depression beginning later in life (late-onset). Although the relation between inflammation and depression has been studied extensively, the distinct role of inflammation in early and late-onset depression in older patients has not been addressed before. In the cross-sectional part of this study, we explored differences in levels of circulating inflammatory markers and cytokine levels in lipopolysaccharide (LPS) stimulated whole blood between older subjects with a late-life onset depression (≥60 years) and older subjects with an early-onset depression (