Executive dysfunction in depression in adolescence: the role of inflammation and higher body mass

There is substantial evidence that many depressed individuals experience impaired executive functioning. Understanding the causes of executive dysfunction in depression is clinically important because cognitive impairment is a substantial contributor to functional impairment. This study investigated whether elevated levels of an inflammatory cytokine [interleukin-6 (IL-6)] and/or higher body mass index (BMI) concurrently and/or prospectively accounted for the relationship between depressive symptoms and impaired executive functioning in adolescents.

A diverse, community sample of adolescents (N = 288; mean age = 16.33; 51.4% female; 59.0% African-American) completed assessments of height and weight, IL-6, depressive symptoms, and self-report/behavioral measures of executive functioning (selective attention, switching attention) and future orientation annually over 3 years. Adolescents experiencing acute illness or medical conditions that affect inflammation were excluded from analyses. Path analysis within a structural equation modeling framework simultaneously examined the concurrent and prospective relationships between BMI, IL-6, depressive symptoms, and the measures of cognitive functioning across three timepoints.

Across all timepoints, higher BMI was prospectively associated with higher levels of IL-6 and depressive symptoms, while higher levels of IL-6 were associated with worse performance on three behavioral and self-report measures of cognitive functioning. Higher depressive symptoms also were prospectively associated with elevated IL-6 and both higher depressive symptoms and a higher BMI predicted worse future executive functioning via increased IL-6.

More severe depressive symptoms and increased BMI may disrupt executive functioning via elevated IL-6.