Examining the construct of depression in obstructive sleep apnea syndrome

Background and purpose Depression is commonly reported by patients suffering from Obstructive Sleep Apnea Hypopnea Syndrome (OSAS). We used the factor structure of the Beck Depression Inventory–2nd edition (BDI-II) to examine the unique contributions of OSAS severity and obesity to depressive symptoms in OSAS. We predicted that the Somatic and Cognitive dimensions of the BDI-II would be more strongly associated with apnea severity and obesity, respectively. Patients and methods Ninety-three moderate to severe OSAS patients (61 men, 32 women) were seen for psychological testing prior to initiating CPAP treatment. They completed the BDI-II and Epworth Sleepiness Scale (ESS). Measures of apnea severity (RDI, percent of sleep time below 90% oxygen saturation) and BMI were also collected. Results RDI was significantly related to BMI and BDI-II total score, but not to ESS score. BMI was related to BDI-II total score and ESS score. Partial correlations indicated that RDI was independently related to the Somatic dimension on the BDI-II. By contrast, BMI was uniquely associated with the Cognitive dimension. Although there was no difference in depression scores between men and women, the relationship between the Somatic factor and apnea severity was significant in men, whereas obesity and the Cognitive factor were significantly associated in women. Conclusions OSAS severity and obesity contribute differentially to symptoms of depression in OSAS. In addition, symptoms of depression in OSAS manifest differently in men than in women.