By JOHN O'NEIL
Cognitive therapy and medication are regarded as equally effective in treating depression. But they work in very different ways, according to a study released yesterday comparing brain scans of depressed patients before and after treatment.
The study, which was published in The Archives of General Psychiatry, involved 14 patients who attended 15 to 20 sessions of therapy and 13 comparably depressed patients who were treated with paroxetine, an antidepressant better known by its brand name, Paxil.
The cognitive therapy provided for the patients aimed to reduce depression by teaching them to recognize and derail negative habits of thought.
The study's senior author, Dr. Helen Mayberg of the Rotman Research Institute of Toronto, said scientists had speculated that the therapy had a "top down" action on the brain: changes beginning in the cortex, the area dealing with higher reasoning, go on to affect other areas of more basic functioning.
By contrast, research has suggested that antidepressants work as "bottom up" agents, working first on areas like the limbic system that play a big role in memory and basic emotions.
The brain scans supported this analysis, the study said. The scans showed that the therapy led to changes in the use of parts of the frontal cortex that were not changed in the patients who took Paxil. Those patients, by contrast, showed changes in the brain stem and parts of the limbic system where the cognitive therapy appeared to have no effect.
Dr. Mayberg said the findings could help explain why a combination of the two approaches was often better than either one alone. "They're having effects on areas that don't overlap," she said.
Since some patients respond to one kind of therapy but not the other, the research could lead to better tailoring of treatment, she said.