Substance Abuse as a Risk Factor for Schizophrenia and Related Disorders

Abstract

The concept that substance abuse might be a risk factor for schizophrenia and related disorders is somewhat controversial. It seems clear from clinical experience that substance abuse, often involving several potentially psychotogenic agents, may precede, for varying periods, the onset of psychosis. However, the interpretation of this phenomenom in retrospect is problematic. Some observers, for example, believe that drug use may be an attempt to self-medicate depression or other early symptoms of impending psychosis though much adolescent drug use seems to be related primarily to peer behavior. Most studies indicate that patients who first become psychotic after a period of substance abuse do not have atypical developmental histories and prominent negative symptoms, as do many adolescents who develop a chronic psychotic disorder. It may be that relapsing psychosis initiated by psychotogenic drug use, but not dependent upon continued use, is a partial phenocopy of schizophrenia and related disorders with primarily positive symptoms. However permanent a drug-initiated psychosis becomes, most investigators would agree that even temporary psychosis is neurobiologically harmful. Thus, ideas of reducing drug use as a risk factor for the major psychoses are worthy of consideration. How often does psychotogenic drug use precede the onset of first-episode psychosis? The answer to this question is critical if we are to entertain possibilities for primary prevention. In our initial study of first-episode patients who became psychotic after cannabis and/or lysergic acid diethylamide (LSD) use, all had started their drug use before being initially hospitalized for psychosis [1]. Alienbeck, Adamsson, & Engstrom [2] found that 69 percent of a sample of 1 12 patients with schizophrenia who used cannabis had started using the drug at least a year before the onset of psychosis. Linszer, Dingemans, & Lenior [3] reported cannabis use