Vaidya and his colleagues subjected rodents to the early-life stress of maternal separation, then examined its impact on the animals' brains and behaviors in early adulthood and midlife. They found that in early adulthood and compared with controls, the animals exhibited enhanced neurogenesis in the hippocampus; enhanced expression of brain-derived neurotropic factor (BDNF), which is a key modulator of neurogenesis, and enhanced learning while under stress—all signs of adaptation to early-life stress. In contrast, in middle age, the animals showed reduced neurogenesis in the hippocampus, reduced BDNF expression, and reduced memory capabilities—all signs of maladaptation to early-life stress.
The findings thus "raise the intriguing possibility that while early adaptive outcomes may enhance cognitive function under stressful conditions, such enhanced fitness may eventually extract a high cost," the researchers said. However, the deleterious effects can be remedied, they also found. When rodents that experienced maladaptation to early life stress were treated with an antidepressant, it prevented neurogenic decline in the hippocampus, decreased BDNF expression, and memory decline.
For more on rodent models of studying mental illness, see Psychiatric News here. Neurogenesis was also the topic in an edition of the PBS television series "Healthy Minds," in which host Jeffrey Borenstein, M.D., editor-in-chief of Psychiatric News, interviews Eric Kandel, M.D., winner of the 2000 Nobel Prize in Physiology or Medicine, and award-winning writer Sharon Begley, science editor for Newsweek, who explains how neuroplasticity can help stroke victims and provide insight into brain cancer and other areas.