Dr. sutton performed some tests and beieves the abnormal behaviors richard is displaying are casued by

 The answer is "a chemical imbalance".

Human body is full of various chemicals in various forms; some are hormones, some enzymes and neurotransmitters etc. A research into the study of these chemicals shows that various behaviors as well as disorders are caused by an imbalance of various chemicals in our bodies.

answer; migrate from a region;