Adipokines May Be the Link Between Mood Disorders and Obesity
Researchers David J. Bond and Lakshmi Yatham think they may have identified why bipolar disorder and obesity occur so often together. In North America, more than 60% of people with bipolar disorder are overweight or obese, and obesity rates are 60% higher in people with bipolar disorder than in people without bipolar disorder.
Bond and Yatham hypothesized that adipokines might be responsible for both bipolar disorder and obesity. Adipokines are cell signaling proteins that regulate both mood and appetite. Abnormal levels of adipokines in blood could cause both mood episodes and weight gain.
The researchers measured blood levels of five adipokines (leptin, adiponectin, resistin, adipsin, and lipocalin-2) in 53 young people with bipolar disorder. They found three interesting links between adipokines, mood, weight, and medications, which they reported in the Journal of Clinical Psychiatry in 2017.
The first finding was that low levels of leptin and adiponectin (adipokines with antidepressant properties) predicted a greater risk of depressive relapse over a 12-month period. The second finding was that high levels of leptin and adipsin predicted greater weight gain over a 12-month period. The third finding was that treatment with second-generation antipsychotics, which often leads to weight gain and other metabolic side effects, was associated with higher levels of resistin, an adipokine linked to type 2 diabetes.
The findings about leptin were particularly interesting, because leptin’s appetite-regulating effects change with a person’s weight. In the study, low leptin predicted depression, while high leptin predicted weight gain. In people of normal weight, low leptin predicts weight gain, while in overweight or obese people, high leptin predicts weight gain. Bond and Yatham suggest that leptin’s mood-regulating effects may be more consistent, with low leptin increasing depression risk regardless of weight.
These findings may help researchers find ways of treating mood episodes that do not encourage weight gain.
