When things get really complicated I find I look for ways to simplify them. The following chart (I like flow charts too) helps me to stick with the basics when considering mental health problems:
This chart comes from Blame It On The Brain?, Edward T. Welch, page 116.
Very simplistic? Yes. Too simplistic? No. There is much value in being reminded that there is always heart/spiritual roots with mental health problems that must be addressed.