I agree that physical and mental health are intertwined anatomically and functionally. AD's and counseling go hand in hand for effective treatment of depression. I'm curious how psychs quantify this though. The more we research human health, physically and mentally, the more we realize the underlying mechanisms are biochemical and commissural in nature. What is it a psych thinks he does, physiologically, to alleviate mental health problems? I understand the concept of coping mechanisms and can easily couple it with learned behavior. This does not explain the underlying physiological mechanisms. What is it a psych imagines he compensates or makes a difference by in, say, irreversible neurological damage to the CNS?
Those are really good questions, and I'll answer in two ways. First, we know that psychological interventions work, and in many cases have long term benefits equal to or exceeding medication (and in other cases are inferior to medicine). Since all behavior must necessarily come from the brain, if behavior or thoughts are modified, the brain necessarily is also.
As to the question of how it all happens, that's still a pretty new area of research and I'm no way qualified to represent it. However, can give a pretty basic example of pretty simple rational. Skydiving, an environmental event, produces a rush of dopamine in the brain. We also know that many drugs act directly on the dopamine system. And long term drug use has been proven to cause permanent functional changes in the brain, changes which are visible via MRI and other imaging. That's a pretty simple run down and an actual researcher in that realm could give a much better explaination, but the gist is that the mechanism exists.
As for "irreversible neurological damage", no, psychological interventions are not claimed to heal brain damage. If youre referring to the fact that the brains of chronic depressive patients look different than those of non depressed people, there are 2 things to remember: (1)it says nothing of the cause (the brain could have degenerated and caused depression, or long term depression due to environmental factors could have changed the brain itself over time), and (2)over time, psychological interventions may be able to partially or fully reverse that change
The biological perspective has gained lots of ground recently, and for good reason. But no longer is it an "either or" picture between the environmental folks and the biological folks. Everyone now recognizes that both contribute substantially to who we are and what we become (and the environmental factors must necessarily act through the biological)