Millions of Americans suffer from bipolar disorder, depression, and obesity, but it wasn’t until a team of researchers from Umeå University in Sweden investigated that they uncovered a key link between low levels of the stress hormone cortisol and high levels of obesity among depressed and bipolar patients. Their findings, published in the Journal of Affective Disorders, may help lay the foundation for future intervention programs for the at-risk population.

"These results provide clues to better understand the high prevalence of cardiovascular diseases in people with recurrent depressions or bipolar disorder,” said the study’s lead author Martin Maripuu, a psychiatry researcher at Umeå University, in a statement. “The results may in the future contribute to better preventative treatments of cardiovascular diseases in these disorders."

For the study, researchers evaluated the health of 245 patients who were diagnosed with bipolar disorder or chronic depression by looking at their cortisol levels, blood sugar, blood pressure, obesity, levels of fat in their blood (dyslipidemia), and potential metabolic syndrome, including obesity. They compared the group of bipolar and depressed patients to 258 participants who were otherwise healthy.

Maripuu and his team found patients who had consistently low levels of cortisol were more likely to be obese (34 percent), had higher levels of fat in their blood (42 percent), and had metabolic syndrome (41 percent).

Depression Weight Gain
Long-term stress can put bipolar and depressed patients at risk for excessive weight gain. Photo courtesy of Pixabay, public domain

In general, humans respond to stress through a complex system that affects nearly every part of the body, from the brain down to the stomach. But once cortisol suppresses the immune system, it slows down digestion and causes a blockage that could lead to sleeplessness, depression, and obesity. When a person is suffering from bipolar disorder or depression, they experience high levels of cortisol in their system as a result of long-term stress. Over time, chronic stress causes the body to go into crisis mode, which in turn drops cortisol levels low enough to trigger even more weight gain.

According to the Depression and Bipolar Support Alliance, bipolar disorder, also known as manic depression, affects roughly 5.7 million American adults. The mental illness causes a person to fall victim to mood swings of extreme highs and lows. Although bipolar disorder is manageable through medication and therapy, it can still disrupt a person’s ability to carry out a normal life. Those suffering from the illness are also at higher risk for heart disease, which leads to a 10- to 15-year reduction in life expectancy — another possible consequence of obesity and high levels of fat in the blood. Depression, on the other hand, manifests differently; yet it can still cause problems with cortisol regulation and trigger weight gain in the same way as bipolar disorder.

Bipolar and depressed patients may be especially sensitive to cortisol, which leads them to gain extra fat even when they aren’t stressed. But until researchers look into exactly how cortisol functions in the body, the experts will have to speculate.

Maripuu explained: “Cortisol regulation is linked to worsened physical health in people with bipolar disorder or recurrent depressions. However, further studies are needed in order to better understand these associations.”

Source: Maripuu M, Norrback KF, Wikgren M, Karling P, and Adolfsson R. Relative Hypocortisolism Is Associated With Obesity and the Metabolic Syndrome In Recurrent Affective Disorders. Journal of Affective Disorders. 2016.