Antidepressant drugs not only relieve depression, but may protect the brain too, according to research that has shown a direct link between antidepressant consumption and size of the hippocampus in women with a history of depression.
Studies have shown that bouts of severe depression increase vulnerability to more of it and are associated with a smaller hippocamus, the seat of memory. Animal research suggests that antidepressants can help keep the hippocampus intact (Science, 13 October 2000, p. 258).
The latest study, headed by psychiatrist Yvette Sheline at Washington University in St. Louis, has now shown that this principle appears to hold true for humans. Subjects were 38 women with a history of recurrent depression. Brain scans revealed that the subjects had hippocampal volumes about 10% smaller than those of undepressed controls. Among the depressed women, those who had suffered the most days of untreated depression also showed the greatest reductions in hippocampal volume, the researchers report in the August issue of the American Journal of Psychiatry. In other words, antidepressants not only counter depression but may well be bolstering the brain against damage that could lead to further onslaughts of depression.
Psychiatrist Robert Post of the National Institute for Mental Health says the research supports the relatively new idea that antidepressants may boost levels of growth factors that keep neurons healthy. Levels of brain-derived neurotrophic factor (BDNF), for instance, are low in depressed patients. Animal research has shown that stress reduces BDNF levels and antidepressants raise them. "This is the first study to suggest the preclinical findings might be relevant to humans," says Post.
The message to doctors and patients is clear, Post adds. People hounded by depression should be encouraged to look at antidepressants as having a role like digitalis, a routine daily medication for heart disease. "People would rarely recommend family members go off digitalis and see if they have a new bout of congestive heart failure," Post says. "But that's what often happens" for people taking antidepressants.