From Yale: Psychiatric disease and drug abuse

http://www.ncbi.nlm.nih.gov/pubmed/22327950

Curr Opin Pediatr. 2012 Feb 9. [Epub ahead of print]
Psychiatric disease and drug abuse.
Santucci K.
Source
Yale University School of Medicine, New Haven, Connecticut, USA.

Abstract
PURPOSE OF REVIEW:
The term 'dual diagnosis' most commonly refers to the combination of severe mental illness and substance-use disorder (SUD). It is estimated that 7-10 million people in the USA alone have at a minimum one psychiatric disorder in addition to a SUD. As many of the psychiatric illnesses implicated have their origins in childhood, the pediatric population is not immune to this 'dual diagnosis', particularly with the increasing availability of street drugs and increasing accessibility to prescription drugs. The purpose of this review is to identify the magnitude of the problem and strengthen awareness among pediatric healthcare professionals who may provide prevention and/or early intervention.

RECENT FINDINGS:
Causes for the dual diagnosis are unknown, but there are four hypotheses: common factors (risk factors common to both disorders), secondary mental disorder (substance use precipitates mental disorder), secondary substance use ('self-medication hypothesis') and bidirectional (presence of either mental illness or SUD can contribute to the development of the other).

SUMMARY:
Those with the presence of this dual diagnosis are more likely to be nonadherent to treatment and may well have poorer outcomes. Integrated care for the maladies rather than split or isolated care is recommended. Psychosocial therapy holds promise for treating patients with dual diagnosis.