The role of stigma on inflammation in depressed and non-depressed bariatric patients

Abstract

Background. Depression is prevalent among post-bariatric surgery patients, yet its psychosocial determinants remain underexplored. Weight stigma, both perceived and internalized, is linked to depression and systemic inflammation. Very few studies have examined these associations using validated clinical depression scales alongside inflammatory biomarkers, limiting understanding of their combined impact and informing the need for targeted interventions in bariatric patients.

Method. This observational study included 37 post-bariatric surgery patients after three years of follow-up, comprising 15 cases with depression and 22 controls. Before and after 3 years of surgery, depression was evaluated by clinical interview, Weight stigma was assessed using self report questionnaires, and measured serum inflammatory cytokines, including Tumor Necrosis Factor-alpha (TNF-α) and Interleukin-6 (IL-6).

Results. After surgery, inflammatory cytokines TNF-α and IL-6 were significantly elevated in depressed patients. All stigma scales correlated with depression, with SSI-B showing the strongest associations: HAM-D-17 (r = .546, p < .001), atypical depression (r = .396, p = .019), and SIGH-ADS (r = .554, p < .001). TNF-α and IL-6 correlated only with BMI. In regression analyses, SSI-B independently predicted HAM-D-17 (B = 0.230, p = .004) and SIGH-ADS (B = 0.312, p = .005), while WBIS predicted atypical depression (B = 0.159, p = .031). WCS and cytokines were not independent predictors.

Conclusions. Weight stigma showed stronger associations with depression than inflammatory cytokines beyond the effect of BMI and other confounders. highlighting psychosocial factors as key targets. Interventions addressing weight stigma may be critical for improving mental health outcomes among bariatric patients.