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Powerless chemistry of depression.

Laboratory animals exposed to uncontrollable and unpredictable stress, such as foot shocks or loud noises, rapidly learn that they cannot control their environment. When experimenters subsequently offer them various tactics to avoid these intrusions, such as pressing a lever, the animals refuse the options and resign themselves to further discomfort.

Psychologists have theorized that a comparable type of giving up, or "learned helplessness," lies at the root of some cases of human depression. A new report, published in the June AMERICAN JOURNAL OF PSYCHIATRY, suggests that severely depressed people who show evidence of elevated activity by a particular chemical messenger in the brain are most likely to feel powerless and at the mercy of others.

Pervasive perceptions of powerlessness may be either the cause or the result of a surfeit of this chemical messenger, norepinephrine, assert psychologist Jacqueline A. Samson of McLean Hospital in Belmont, Mass., and her colleagues.

The researchers measured concentrations of a norepinephrine by-product, MHPG, in urine samples obtained over a 24-hour period from 20 adults hospitalized for severe depression. Participants-who had not taken any psychoactive medication for at least 10 days-also filled out a psychological questionnaire with separate scales that measure feelings of alienation, security and powerlessness.

In previous studies, urinary MHPG levels ranged widely among depressed patients. But Samson's team found higher MHPG levels among volunteers who believed that society in general or specific others controlled their lives. In contrast, no association appeared between MHPG levels and feelings of powerlessness due to fate, chance, luck or forces beyond one's comprehension.

Although scientists do not know the exact proportion of urinary MHPG that derives from the brain, Samson and her coworkers note that animal studies have shown a strong link between learned helplessness and higher brain levels of the substance.

Depressed patients with greater amounts of urinary MHPG often prove less likely to benefit from antidepressant drugs, they add. Cognitive-behavioral therapy, which attempts to correct negative perceptions and behaviors, may provide the best treatment for "powerless" depression, the researchers suggest.
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Publication:Science News
Article Type:Brief Article
Date:Jun 13, 1992
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