NEUROBIOLOGY OF CYCLIC AFFECTIVE ILLNESS: IMPLICATIONS FOR TREATMENT, excerpts from a presentation1 by Robert M. Post, M.D.,2 Smooth Sailing, Summer 1996, pp. 2,3.

Dr. Robert Post [discussed] the vital roles that neurobiology can play in helping to explain affective disorders and in targeting treatment.

We have known for about 75 years that an episode of affective disorder may be triggered by a major experience in a person's life, such as the death of a loved one. Only recently, however, have advances in neurobiology begun to show us how this can happen. Research indicates that the impact of a traumatic experience actually changes gene expression (that is, what genes are currently acting) and, therefore, brain biochemistry. Each episode of depression is thought to increase vulnerability to further episodes. At present, it seems probable that a traumatic experience sets off a chain reaction of changes in neuronal (nerve cell) firing, messenger RNA, gene expression, and hormones that influence the central nervous system, eventually producing symptoms. We need to understand more about the mechanisms involved in this process. The structure of the hippocampus has been shown to change, and very recent research by Dr. Post and coworkers suggests that most depressed patients have decreased glucose metabolism in the frontal cortex of the brain.

In other words, life events affect the central nervous system and actually tune both long-term regulation of impulse transmission between neurons and functioning within neurons. This sensitization model suggests that as depressive illness continues, increasingly fewer stressors are needed to trigger an episode. This model is not unique. The kindling model, as it applies to seizures, suggests that each seizure occurrence increases the chance for another seizure. Eventually, Dr. Post said, a trigger stressor is no longer needed, and the system goes on automatic. At this point, neuronal pathways are sufficiently sensitized that depression can occur spontaneously.

Dr. Post strongly emphasized the importance of "ganging up" on the depressive illness—that is, treating it aggressively, early, and preventively to keep the nervous system from becoming set in the patterns of the disorder. According to the sensitization model, each depressive episode can increase the chance of a future episode. Family members can be instrumental in helping the patient get proper treatment. Depression is a serious illness and should be treated as one.

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1Presented at a DRADA/Johns Hopkins symposium, April 23, 1996.

2Chief, Biological Psychiatry Branch, National Institute of Mental Health.

by Ann M. Bain, Ed.D.
Smooth Sailing: Summer 1996

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