When patients first began reclining on the couches of psychoanalytic psychiatrists, the depressed folks talked about their past. This led the founders of psychology and psychiatry to believe that issues that began in childhood caused many mental health problems. But questions were still not answered. Why would a bad relationship with your mother create the appetite loss found in depression, especially when eating problems only started several months prior to the session? By what strange mechanism would a childhood issue create an auditory hallucination, often years after the reported traumatic event? Many people had difficult childhoods, but they didn't hallucinate and have a great appetite. It became clear that many mental health problems also had a physical component that involved changes in concentration, sleep, appetite, speech pattern, energy level, perceptions (hallucinations), and motivation. Studies began to determine the connection, if indeed one was present, between the condition of the patient and the physical signs/symptoms that were also present.

Quoted from:
http://www.mental-health-matters.com....php?artID=160