Both groups showed changes in ventral limbic sites associated with emotion (mood) AND dorsal cortical regions thought to mediate reason and cognition -- a relationship that was first identified by Dr. Mayberg in a landmark study in the American Journal of Psychiatry last year.
But in this study of veterans who did and did not respond to Prozac, the researchers identified a more widespread chain of events kicking in across a system of brain regions from one week to six weeks -- and only in the responders! This chain of events was not limited to the limbic and cortical sites. The cingulate, an area associated with emotional processing, and the hippocampus, an additional limbic region associated with memory and modulating stress, showed signs of "switching off" -- or decreased metabolism -- as the depression went into remission. Failure of these two regions to switch off was seen in those patients not responding to Prozac.
"We know anti-depressants work, but we don't know why they don't work for everyone," says Dr. Mayberg, an internationally-renowned neurologist who specializes in depression.
"Now that we have identified a distinct chain of events in the brains of people who respond well to a specific anti-depressant, we can start to investigate if the same is true for other anti-depressant medications as well as non-drug therapies. We can also use this knowledge as a basis for investigating new strategies, including more aggressive treatments, that induce or manipulate this chain reaction for all patients earlier in their treatment."
Dr. Mayberg likened the anti-depressant's effect on brain regions to "recalibrating" the system to bring it into a healthy balance once again.
"It's not as simple as adding Prozac or any other anti-depressant drug to the tank and depression will go into remission," she says. "There is a whole set of changes that need to happen in the brain to set a path for recovery."
Contact: Kelly Connelly, Media Relations
kconnelly@baycrest.org
416-785-2432
Baycrest
13-Oct-2000