Using chess for therapy? Have there been any studies on using chess for therapy?

If so, what conditions or illnesses have benefited most from using chess as a therapy? Are there certain conditions or illnesses were it has actually been more stressful?
I am not an expert, but an active chess player at chess.com and participate in its forums. Yes, chess can be therapeutic. Playing chess involves co-ordination of different mental abilities like strategy, tactics, intuition, visual imagery, risk analysis, control of emotions, etc. Actively playing chess everyday keeps the mind sharp and attentive. In most cases, it has also shown improvements in mental conditions like ADHD, OCD, Depression, etc.

However, over indulgence into anything is bad and playing compulsively over long duration can effect the individual's thought process. Many schizophrenic persons who play chess start visualizing everything including this life, its people and events as chess moves. If the connection with chess is too deep, real life relations with people are affected. These studies are not confirmed, and are said to be more like "adding order to chaos" from schizophrenic mind's perspective.