Other researchers have found a specific genetic vulnerability caused by having two copies of a variant of the serotonin transporter gene that appears to increase the risk of depression through an interaction with stressors.
Cortisol, the key stress hormone, is ultimately controlled by the brain. It, in turn, influences genes in the brain. Brain control over cortisol is exerted in part by neurotransmitters -- the chemical messengers in the brain -- including serotonin. The relationship between elevated cortisol and depression was first shown in the 1950s.
But there is a chicken and egg question that arises here. Does the stress hormone abnormality cause depression, or is it the result of depression?
One way to disentangle this is to study relatives of people with depression rather than patients themselves.
A study in the April issue of the American Journal of Psychiatry looked at people who have never been depressed, but who have a relative with depression, and compared them to those without such a family history.
Cortisol levels were found to be higher in those who have depression in their families, suggesting there is a vulnerability present even in those who have never been ill.
If genetics play a role in this vulnerability, which genes are the key players? One that has been implicated may influence the recurrence of depression and the speed of response to antidepressant medications. We are studying this gene in our own laboratory at Johns Hopkins to see if it plays a role in bipolar disorder.
In the meantime, what can we do to reduce stress in patients?
First of all, effective treatment of depression reduces stress. There is a corresponding decrease in cortisol levels following treatment in most patients. We can accomplish this with our existing antidepressants, and there are also new drugs being tested for depression focused directly on blocking the stress hormones.
Additionally, most of the psychotherapy we do, the talk therapy, has a stress reduction element to it.
More specific techniques aimed at stress include education about stress as an imbalance between the level of demands and the coping skills available to handle them; instruction in progressive muscle relaxation and meditation; training in assertiveness, problem solving and time management; and strengthening social supports.
Dr. James Potash is an associate professor of psychiatry and co-director of the Mood Disorders Program at the Johns Hopkins School of Medicine in Baltimore. If you have questions or comments, please e-mail at firstname.lastname@example.org. To participate in our studies, call 1-877-MOODS-JH.