title: Revisiting the 'self-medication' hypothesis in light of the new data linking low striatal dopamine to comorbid addictive behavior.
abstract: Persons with schizophrenia are at a high risk, almost 4.6 times more likely, of having drug abuse problems than persons without psychiatric illness. Among the influential proposals to explain such a high comorbidity rate, the 'self-medication hypothesis' proposed that persons with schizophrenia take to drugs in an effort to cope with the illness and medication side effects. In support of the self-medication hypothesis, data from our earlier clinical study confirmed the strong association between neuroleptic dysphoria and negative subjective responses and comorbid drug abuse. Though dopamine has been consistently suspected as one of the major culprits for the development of neuroleptic dysphoria, it is only recently our neuroimaging studies correlated the emergence of neuroleptic dysphoria to the low level of striatal dopamine functioning. Similarly, more evidence has recently emerged linking low striatal dopamine with the development of vulnerability for drug addictive states in schizophrenia. The convergence of evidence from both the dysphoria and comorbidity research, implicating the role of low striatal dopamine in both conditions, has led us to propose that the person with schizophrenia who develops dysphoria and comorbid addictive disorder is likely to be one and the same.
authors.affiliation: Department of Psychiatry and Institute of Medical Science, University of Toronto, Humber River Hospital, 2175 Keele Street, Room 243A, Toronto, Ontario M6M 3Z4, Canada.
authors.forename: A George
authors.initials: AG
authors.lastname: Awad
authors.affiliation: Department of Psychiatry, Oakville-Trafalgar Memorial Hospital, Oakville, Canada.
authors.forename: Lakshmi L N P
authors.initials: LL
authors.lastname: Voruganti
keywords: DSM5; antipsychotics; comorbid drug abuse; low striatal dopamine; neuroleptic dysphoria; schizophrenia; subjective negative responses