The Association of Inflammation with Obesity and Depressive Symptoms Among People with Multiple Cardiovascular Disease Risk Factors

Purpose: Obesity and depression are associated with inflammation. Inflammation is a biological mechanism underlying cardiovascular disease (CVD). Obese people with depression may be at a greater risk for CVD due to increased inflammation, compared to obese people without depression or non-obese people with depression. However, potential combined effects of obesity and depression on inflammation have not been investigated. The purpose of this study was to examine combined effects of obesity and depression on the inflammatory marker, high sensitivity C-reactive protein (hs-CRP), in people with multiple CVD risk factors.

 Methods: A total of 859 people (52 yrs, 75% female) provided blood for serum hs-CRP and had height and weight measured for body mass index (BMI=kg/m²). The Patient Health Questionniare-9 (PHQ-9) was used to measure depressive symptoms. Hierarchical regression was used to examine whether the interaction of BMI and depressive symptoms (BMI*PHQ-9) predicted hs-CRP levels after controlling for covariates (age, gender, HbA1C, and smoking history). In Step 1, covariates and depressive symptoms were entered, followed by BMI in Step 2. In Step3, the interaction of BMI and PHQ-9 scores (BMI*PHQ-9) was added.

 Results: In Step 1, PHQ-9 scores independently predicted hs-CRP levels. In Step 2, BMI, but not PHQ-9 scores, independently predicted hs-CRP levels. In Step 3, there was no BMI* PHQ-9 interaction; only BMI predicted hs-CRP levels (Table).

 Conclusions: In the company of obesity, depressive symptoms do not significantly contribute to increased inflammation in people with multiple CVD risk factors. This study suggests that obesity is more strongly linked with inflammatory processes relevant to cardiovascular risk than depressive symptoms in this population.

Table. Predictors of hs-CRP (N=859)

Outcome= hs-CRP(log-transformed)
Step 3	Unstandardized ß	standardized ß	p-value
PHQ-9 scores (depressive symptoms)	.03	.97	.33
Body mass index (BMI)	.06	8.50	<.001
BMI * PHQ-9 scores	-.001	-.10	.46

 Note. Covariates included in the model (Step 3):  age, gender, HbA1C, and smoking history