and very happy to hear your psychiatrist answered your question in this way! I've posted the following info, several times:
Since 1956, the American Medical Association has recognized and defined alcohol addiction as a primary disease, not a secondary symptom of an underlying psychological or medical illness. Since then, this definition has been extended to define all chemical addictions as "chronic, progressive diseases characterized by significant impairment that is directly associated with persistent and excessive use of psychoactive substances. Impairment may involve physiological, psychological, or social dysfunction."
Research into the neurochemical basis of addiction points to the dysfunction of one or more of six major neurotransmitter types as being the basis of the symptoms of addiction, withdrawal, and drug cravings. Studies have shown strong genetic predisposition to some types of chemical dependency regardless of social environment.
http://www.lakesidemilam.com/DiseaseOfAddictionSynopsis... Glossary of relevant terms, fyi:
http://www.lakesidemilam.com/GlossaryOfTerms.htm