The problem with the mechanistic theories of physio-psychology is that they lead to passivity. If one is simply a victim of some chemical imbalance or genetic aberration, then some chemical solution is available to correct the deficiency. The sufferer needn't take any more responsibility for his condition than going to a doctor for a prescription.
There are clearly cases where the root cause of depression is chemical. But just as heliobacter is not the sole source of ulcers, chemical imbalances are not the sole source of depression. And just as the brain is capable of creating the chemicals that cause depression, it is capable of creating those that cause euphoria.
So one walks a dangerous line when one relies completely on a mechanistic model of psychology, just as one does if the model is entirely mystical.
Agreed. As I said, Does doubt and worry cause these imbalances, or do they result from them? However, we once believed wrong things about disease until we found the microbe was the cause. Then there is vitamin defficiency, trauma from physical wounds that appear in other areas, and much more. I agree with the balancing, however. Still, the world today will (hopefully) soon be gone. The Kingdom to come will not have disease in any form.
Until such Glorious Times, we need to understand that a broken mind may be very much like a broken bone, and needs medical help, not Spiritual. The Spiritual let's us deal with the pain and transcend it, not cure it.