Departments: Your Questions Answered
Q Does long-term, severe clinical depression have neurologic effects on the brain?
DR. KENNETH HEILMAN RESPONDS:
A Depression has many harmful effects that extend beyond mood. For example, depression has been shown to damage the immune system: People with depression have longer recovery rates from diseases as well as shorter life expectancies than people without depression. In addition, the anxiety associated with depression has been shown to put people at risk for high blood pressure.
Recent studies suggest that the increased level of stress associated with depression may raise levels of glucocorticoid. This steroid can have harmful effects on the nervous system, damaging a region of the brain called the hippocampus that is crucial to creating long-term memories. In patients with Alzheimer's disease, the hippocampus is one of the first regions in the brain to degenerate.
The importance of the hippocampus in memory function was demonstrated by the famous case of H.M., a man who had his temporal lobes and much of his hippocampus removed in 1953 to treat his severe epilepsy. Although the epilepsy was alleviated, H.M. experienced a rare form of amnesia—called anterograde amnesia—as the result of the surgery. Anterograde amnesia makes it difficult to form memories of new events, experiences, or situations.
Some depressed patients may show symptoms of dementia, such as memory loss. Once their depression is treated, these symptoms often lessen.
When it comes to depression, the earlier treatment begins and symptoms are controlled, the better. As a result, neurologists and psychiatrists treat the condition aggressively. A combination of psychotherapy and drug therapy has been shown to be very effective in combating depression.