Low Levels of Cortisol in People with Bipolar Disorder Linked to High Depression Risk

Cortisol, the stress hormone, is known to cause several problems such as memory loss and inflammation. But, a new study has found that low levels of the hormone could actually be increasing depression risk in people with bipolar disorder.

The study was conducted by researchers at tthe Umeå University and colleagues. It is published in the open-access journal PLOS One.

People who suffer from bipolar disorder undergo radical mood swings - from being depressed to being highly excited. The phases are called mania and depression.

Researchers say that both over and underactive stress mechanism contributes to depression risk and low quality life in bipolar disorder patients. But, low levels of the hormone leads to more mental health problems than having high levels of cortisol.

"In bipolar depression the stress system is often activated, which means that the affected individuals have elevated cortisol levels in the blood. We have now been able to show that both over- and underactivity in the stress system, with corresponding elevated or reduced cortisol levels, can impair mental health in terms of depression and poor quality of life in these patients," said Martin Maripuu - a PhD student at the Department of Clinical Sciences, Psychiatry Unit Umeå University and physician at the psychiatric clinic, Östersund Hospital, according to a news release.

Stress is a known trigger for bipolar disorder episodes. The HPA axis is the body's main stress system and controls cortisol production.

The hormone cortisol is the body's primary defense against stress and is known to keep human alert during an emergency situation.

The study was based on data from 145 patients who had bipolar disorder and 145 patients in the control group. All participants underwent dexamethasone suppression test, which tests abnormalities in stress system. Researchers even measured participants' cortisol levels.

Study results showed that more than half of the patients with low or high stress hormone levels also had depression.

Also, depression was twice as common in people with high cortisol levels as others. Additionally, people with bipolar disorder- with high or low cortisol levels  - had lower quality of life than people with normal stress response mechanism.

According to researchers, bipolar disorder leads to an "exhausted" stress system. Bipolar disorder patients with low cortisol levels have a chronic form of the disorder.

"These are important results that in the future could contribute to a more personally tailored medical treatment of bipolar disorder. The results may also ultimately lead to the development of new drugs that work by normalizing the stress system and cortisol levels," said Martin Maripuu.