Re: Exercise Decreases Depression --> Why?
thanks a lot for your insight! In short I really like the psychological mechanisms you discussed, and they do have evidence supporting them.
The article I am going to publish with Gabriel in particular addresses actual structural changes that occur in the brain with exercise.
Its interesting, but the theme of the article is this
1. The evidence is clear that exercise lowers depression as well as and in cases to a greater extent then drugs
2. Both drugs and exercise appear to raise similar hormone and neurotrophic factors (factors that increase neuron health, and even new neuron formation).
These include for example
1. Insulin like growth factor
2. Epinephrine / Norephinephrine
4. Endorphins ( which has a lot of contraversy but we argue that there is a great deal of support for this).
3. We propose that the mechanism that these substances operate are to actually cause structural changes in the brain, in particular 'neurogenesis' or the formation of new neurons in the brain.
4. Evidence for this
1. People depressed have atrophied or lower brain volumes
2. Exercise appears to reverse this
3. In animal models of depression, if neurogenesis is hindered then the depression effects of both exercise and or drugs is also hindered.
So the take home message is this: Exercis actually has real, substantial structural, and measurable changes in the brain, including the formation of new neurons, and increases in the complexity of those neurons! In contrast a sedentary lifestyle does the opposite.
Also I will discuss intensity and other factors.
I'll release a more detailed paper on our site in about 2 weeks with the other articles, like leucine and such like. But the paper for the site will be less technical and more clear than the technical version submitted to Medicine and Science in Sports and exercise