Canadian neuroscientists have found that behavioural therapy for depressed patients causes different changes in brain activity than anti-depressant drugs, a discovery that could lead to new diagnostic tools for doctors and help them tailor treatment for their patients.
Right now, doctors try various treatments for clinically depressed patients until they find one that works. In contrast, cardiac experts use various tests to decide whether to treat someone who has had a heart attack with drugs or bypass surgery.
"It shouldn't be hunt-and-peck, luck of the draw," says Helen Mayberg, a researcher at the Rotman Research Institute at Baycrest Centre for Geriatric Care in Toronto.
She says both anti-depressants and what is known as cognitive behavioural therapy help about 60 per cent of depressed patients. Cognitive behavioural therapy, or CBT, is used to treat a range of mental illnesses. Someone with a severe spider phobia, for example, would learn to manage the symptoms of anxiety while looking at pictures of spiders. In depression, CBT attempts to train patients to handle negative events without sliding into depression.
Some depressed patients respond to CBT and not to anti-depressants, or the other way around. Some do best with both. Dr. Mayberg hopes that her studies are the first step toward a diagnostic tool that would allow doctors to determine which therapy to try first.
Using brain imaging, her team found that patients who recover from depression with the help of CBT have different physical changes to their brain than patients who recover by taking drugs.
While both drugs and CBT are equally effective, CBT may be better at preventing a relapse.
Many people, however, don't have access to CBT, especially if they live in rural areas.
Dr. Mayberg's study, published in the January edition of the Archives of General Psychiatry, is the first to show that the networks in the brain involved in depression can be corrected in different ways.
In their study, Dr. Mayberg and fellow researchers Kimberly Goldapple and Zindel Segal did brain scans of 14 clinically depressed patients who underwent a full course of CBT, 15 to 20 sessions.
They compared their findings to previous brain scans done on patients who underwent successful drug therapy, and found the results were different.
They found that CBT brings about changes in the top of the brain, in areas associated with thinking. Depressed patients probably use these parts of their brain when they ruminate about their problems. The study showed that the therapy resulted in a decrease in activity there.
Scans of patients who were successfully treated with drugs showed a decrease of blood flow to the bottom of the brain, in areas that drive more basic emotional behaviour. The theory is that changes there eventually result in changes in depressive thinking, Dr. Mayberg says.