A new study by a researcher at Karolinska Institutet in Sweden has found that exercise stimulates the production of new brain cells.
The finding also helps explain just how exercise keeps depression at bay.
Previous research had shown that exercise has similar effect to antidepressants on depression, and now Astrid Bjornebekk has found that this process happens as exercise stimulates the formation of new brain cells.
Bjornebekk conducted experiments on rats, and found that both exercise and antidepressants increase the formation of new cells in an area of the brain that is important to memory and learning.
Her studies confirm previous research results, and she proposes a model to explain how exercise can have an antidepressant effect in mild to moderately severe depression. Her study also shows that exercise is a very good complement to medicines.
The effects of exercise were also compared with pharmacological treatment with an SSRI drug.
"What is interesting is that the effect of antidepressant therapy can be greatly strengthened by external environmental factors," she says.
Previous studies have shown that drug abusers have lowered levels of the dopamine D2 receptor in the brain's reward system. It has been speculated that this may be of significance to the depressive symptoms drug abusers often suffer from.
These rat studies show that genetic factors may influence how external environmental factors can regulate levels of the dopamine D2 receptor in the brain.
"Different individuals may have differing sensitivity to how stress lowers dopamine D2 receptor levels, for example. This might be significant in explaining why certain individuals develop depression more readily than others," she says.