Lower Levels of Appetite Control Hormones May Also Account for Depressive Relapse in People with Bipolar Disorder, Study Finds

People who are overweight have a 25 percent higher chance of developing a depressive illness, while people who are obese have a 50 percent higher chance.

Conversely, people with mood disorders are more likely to become overweight.

It’s a well-known relationship that scientists have observed for years. But David J. Bond, M.D. Ph.D, associate professor in the Department of Psychiatry at the University of Minnesota, wanted a biological explanation for this occurrence.

“We constantly ask ‘why’ as scientist physicians because in doing so we may uncover better ways to treat our patients,” Bond said. “To improve their quality of life, I wanted to know why people with conditions like depression and bipolar disorder struggle with weight, and why being overweight makes them more likely to relapse into depression.”

His latest study, published in the current issue of the Journal of Clinical Psychiatry, found an apparent connection between adipokine levels, depression, and body mass index (BMI). Adipokines are a family of proteins produced by fatty tissue. They regulate appetite and metabolism, and more recently have been shown to affect mood.

Over a 12-month period, Bond and colleagues analyzed five different types of the proteins in 53 people with early-stage bipolar disorder.

People with higher levels of two particular adipokines appeared to relapse into a depressed mood less often than those with lower levels, suggesting the proteins may have an antidepressant quality.

In addition, those people who had higher levels of leptin, an adipokine that regulates appetite, saw increases in BMI. At first glance, this seems counter to the expected findings. However, Bond says that high levels of leptin are often associated with obesity because over time, people’s bodies can become resistant to its appetite control effects, which could account for the relationship.

The potential causal effect of adipokines on mood is important to study more, says Bond, because the proteins could make for therapeutic targets in treating mood disorders.

“With additional research, we might find that by administering adipokines to patients, their mood disorders improve. Or, maybe we’ll find how to minimize the weight-related side effects of existing drugs,” he said. “This study is a possible building block for new treatments.”