RT Journal Article SR Electronic T1 Antidepressant effects of exercise: Evidence for an adult-neurogenesis hypothesis? JF Journal of Psychiatry and Neuroscience JO JPN FD Canadian Medical Association SP 84 OP 92 VO 31 IS 2 A1 Carl Ernst A1 Andrea K. Olson A1 John P.J. Pinel A1 Raymond W. Lam A1 Brian R. Christie YR 2006 UL http://jpn.ca/content/31/2/84.abstract AB It has been hypothesized that a decrease in the synthesis of new neurons in the adult hippocampus might be linked to major depressive disorder (MDD). This hypothesis arose after it was discovered that antidepressant medications increased the synthesis of new neurons in the brain, and it was noted that the therapeutic effects of antidepressants occurred over a time span that approximates the time taken for the new neurons to become functional. Like antidepressants, exercise also increases the synthesis of new neurons in the adult brain: a 2–3-fold increase in hippocampal neurogenesis has been observed in rats with regular access to a running wheel when they are compared with control animals. We hypothesized, based on the adult-neurogenesis hypothesis of MDD, that exercise should alleviate the symptoms of MDD and that potential mechanisms should exist to explain this therapeutic effect. Accordingly, we evaluated studies that suggest that exercise is an effective treatment for MDD, and we explored potential mechanisms that could link adult neurogenesis, exercise and MDD. We conclude that there is evidence to support the hypothesis that exercise alleviates MDD and that several mechanisms exist that could mediate this effect through adult neurogenesis.