Depression is common in women with
obstructive sleep apnea (OSA), but objective markers of depression have not yet been explored in such patients. We hypothesized that
inflammation and
antioxidant biomarkers may be associated with depression in a cohort of OSA women. We conducted a multicentre, cross-sectional study in 247 women diagnosed with moderate-to-severe OSA. Depression was assessed by the depression subscale of the Hospital Anxiety and Depression Questionnaire (HAD-D) and defined as a score ≥11. Associations between tumour
necrosis factor α (TNFα),
interleukin 6 (IL-6),
C-reactive protein (CRP),
intercellular adhesion molecule 1 (ICAM-1),
catalase (CAT),
superoxide dismutase (SOD) and
brain-derived neurotrophic factor (
BDNF) plasma levels and depression were assessed. The women had a median (25th-75th percentiles) age of 58 (51-65) years, body mass index (BMI) of 33.5 (29.0-38.3) Kg/m2 , Epworth
Sleepiness Scale (ESS) score of 10 (6-13) and
apnea-hypopnea index (AHI) of 33.3 (22.8-49.3). Logistic regression analyses revealed that only
IL6 levels were associated with the presence of depression (adjusted odds ratio [OR], 1.20; 95% confidence interval [CI], 1.08-1.34), whereas linear regression further confirmed that
IL6 levels were significantly associated with HAD-D scores (β = .154; 95% CI, 0.03-0.30). Multivariate regression analysis showed that
IL6 (OR, 1.22; 95% CI, 1.09-1.36), ESS (OR, 1.10; 95% CI 1.02-1.19) and physical activity <30 min/day (OR, 2.51; 95% CI, 1.25-5.05) were independent predictors of depression. Thus, we conclude that in a cohort of women with moderate-to-severe OSA,
IL6 levels are independently associated with the presence of depression and correlate with depression scores. Low physical activity and higher ESS scores are also independent indicators of risk of depression in this population.