Couldn't agree more!! I also have a chem imbalance, chronic depression - spent some serious time hospitalized, am also a serious runner (compete open @ the D1 level, elite roads) and agree there is a huge connection between my training and disease.
Last hospitalization, was treated by a former Kenyan marathoner (?Olympian) now PhD - Jerry Mungadze - unfortunately, not a psychiartist (dealing w/ meds), but can speak some to running & effects on neurotransmitters and brain chemistry. Recommended that I not drop my mileage below 50/wk...ever
I know I am at extremely high risk if for any reason I have a sudden, significant drop in training - eg, in Jan, went from 75 to 0 due to serious illness, out for 3 weeks.
Running & mental illness is a tricky issue for individuals who at baseline are already athletes - whether D1, mileage hounds, dedicated weekend warriors, runners who just love to run, whatever - than it is for those who have never run before. The benefit is substantially greater for those who have not regularly "indulged"...
SUPER topic though - I'd definately look up Mungadze - and do NOT be spooked by his reputation - suspend judgement until you talk to the man...