Why is mental illness so hard on the heart?
Studies have shown that serious depression is as lethal as smoking. Swedish researchers now think they are closer to understanding why.
Paients with recurrent depression or bipolar disorder live on average lives that are 10–15 years shorter than normal.
A 2010 article in the Norwegian Psychological Association’s journal, Tidsskrift for norsk psykologiforening, concluded that depression is as deadly as tobacco smoking.
Cardiovascular disease is one of the main reasons for this connection. Stress, along with little physical exercise and a high caloric intake are lifestyle factors that raise the risk of these diseases.
Insufficient stress hormone
The connection between mental illness and premature deaths related to cardiovascular disease is well documented. But the workings of this link have not been understood in detail.
Researchers at Umeå University in Sweden think it can be caused by low levels of the stress hormone cortisol.
Stress usually leads to higher levels of cortisol.
But if the stress is chronic and persistent it can lead to lower activity of the system in the body that regulates stress. Then the cortisol levels can fall too low – a condition called hypocortisolism.
The medical researchers at Umeå examined 245 patients and a control group consisting of 258 persons. They measured the levels of cortisol in the two groups after the participants had carried out a test that identifies deviations in the stress system.
The patients with serious depressions or bipolar disorders and had low cortisol levels were more likely to be obese, have high levels of blood fats and suffer a cluster of conditions called metabolic syndrome.
Depressed and stressed
Cortisol is a natural stress hormone that the body produces and needs. Medical researchers at the University of Bergen have found that patients with chronic and recurrent depression have a malfunctioning system for regulating their stress.
The Swedish researchers now think that cortisol regulation also has a link to physical health among patients who are bipolar or are plagued by depression.
“We need more information to understand the connection,” says researcher and first author of the study Martin Maripuu of Umeå University.
Doubts about the causes
Anders Palmstrøm Jørgensen specialises on the hormone system and works at Oslo University Hospital. He finds the study intriguing but is sceptical about the association between cortisol and cardiovascular disease.
“The link between stress and metabolic syndrome, obesity, cardiovascular disease and premature death is well recognised. Studies have shown that chronic stress can lower activity in the adrenal gland – what we call adrenal fatigue.”
However, Jørgensen has strong doubts about hypocortisolism as a key for identifying persons who have lived with chronic stress and are thus at greater risk of developing cardiovascular disease.
“It is unlikely that the low cortisol levels are the reason. We have yet to see whether we should treat adrenal fatigue with cortisol, as many suggest. I don’t think we should.
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Read the Norwegian version of this article at forskning.no
Translated by: Glenn Ostling
