As John stated the whole sub-specialty of psycho-physiological sciences is the object of much controversy and debate amongst medical researchers and clinicians.While further study may finally, and definitively answer the question about pathologic mechanisms/causal link(s) between brain chemistry and mood states(like Parkinson’s diease,etc).What will be needed is to establish valid, reliable diagnostic test(s) that demonstrate true pathology. However,even if a valid, reliable and reproducable evidence is established ,for beleivers the treatment approach, just like treating any other bodily disease would still include include spiritual care.

On the flip side , if we’re operating on theory, and subjectivism when messing with ones brain chemistry,and assigning causation to “disease” then we’re confusing the matter even more than helping a believer dealing with heart/life issues.In fact, we’re doing more harm that good!Dealing with the fallenness of man will always be a part of any biblical approach to shepherding God’s people.
Peter Spiers

Examples:
http://tinyurl.com/bp2hzb
http://tinyurl.com/ahz42y
http://tinyurl.com/d7fblh
http://tinyurl.com/cgtbc4
http://tinyurl.com/btfvux
http://tinyurl.com/5fnkfz

When dealing with behavior that’s abnormal for an individual, physiological and spiritual causes should both be considered. If no objective, verifiable physiological issues arise out of testing, then special and particular attention should be given to the soul. (And even when physiological issues are evident, Scripture notes that those can sometimes be the result of sin, e.g. Ps 32:3-4.)

In all matters of the soul and psyche, we do believe that the Bible is totally & completely sufficient and authoritative, providing all that we need for life and godliness through a vital relationship with Jesus Christ (2 Pet 1:3, 2 Cor 9:8, Ps 19:7-9). This core supposition is the foundation for all biblical counseling.

Hope this helps clarify. For specifics on a particular situation, I’d encourage you to talk to Bob or Peter.