Obesity, Inflammation and Depression

Obesity commonly occurs in the context of markers of inflammation.  Additionally, there is increasing evidence of a link between depression and systemic markers of inflammation such as the cytokine marker interleukin-6 (IL-6).  How these three conditions might tie together is an important research question.

Capuron and colleagues from France recently published a manuscript that looked at a specific group with obesity--women who were severely or morbidly obese and were waiting for gastric obesity surgery. The study published in Psychological Medicine prospectively followed these women after gastric surgery and monitored serum markers of inflammation as well as psychological function.

The research team focused on neuroticism as a key measure of personality as potentially related to systemic inflammation and potentially improved following bypass surgery.  Using the NEO-PI-R inventory, neuroticism can be broken down into components of anxiety, hostility, depression, self-consciousness, impulsiveness and vulnerability.

Baseline obesity levels as measured by the body mass index (BMI) in the sample correlated with baseline inflammatory markers IL-6 and C-reactive proteins.  These inflammatory markers also correlated with anxiety and depression---the higher the level of these inflammatory markers, the higher the level of self-reported anxiety and depression.

The women in the study lost approximately 30% of their body weight in the year following bypass surgery (mean weight reduction 47 kg = 103 pounds) with significant reductions in the blood markers of inflammation.  NEO-PI-R markers of depression and anxiety also dropped significantly over the one year following gastric surgery.  Reduction in C-reactive protein levels correlated with the reductions in the levels of anxiety.

This type of study is a association and not a causation study.  Nevertheless, it suggests that severe obesity is a disorder associated with systemic inflammation.  This systemic inflammation may contribute to adverse affective symptoms such as depression and anxiety.  Reducing inflammation through reducing obesity (via methods such as bypass surgery) may have additional central nervous system benefits.  Psychological benefits of weight loss may also be at work through improved body and self-esteem.

The role of inflammation in a variety of disorders including heart disease and diabetes is becoming better understood.  This study suggests inflammatory mechanisms should be explored for anxiety and depressive disorders, particularly in populations with obesity and diabetes mellitus.  

Photo of Juno Beach sunrise through filter from the author's collection.

Capuron, L., Poitou, C., Machaux-Tholliez, D., Frochot, V., Bouillot, J., Basdevant, A., Layé, S., & Clément, K. (2010). Relationship between adiposity, emotional status and eating behaviour in obese women: role of inflammation Psychological Medicine, 41 (07), 1517-1528 DOI: 10.1017/S0033291710001984