Excess body weight and specific types of depressive symptoms: Is there a mediating role of systemic low-grade inflammation?

OBJECTIVES: Obesity is associated with an increased risk of depression. Systemic low-grade inflammation, a plausible consequence of obesity, has also been linked to depression. However, the potential mediating effects of systemic low-grade inflammation on the association between excess body weight and specific symptom domains of depression remain uncertain. This study examined whether systemic low-grade inflammation mediated the associations of excess body weight (overweight and obesity) with subsequent overall, cognitive-affective, and somatic depressive symptoms. DESIGN: This study used a prospective cohort design. METHODS: The final analytical sample included 4,942 adults aged ≥50 years drawn from the English Longitudinal Study of Ageing (ELSA). Body mass index (BMI) and covariates were ascertained at baseline (wave 4, 2008/09). Continuous BMI scores were divided into four categories: ‘normal weight’ (18.5 ≤ BMI <25 kg/m2); ‘overweight’ (25 ≤ BMI