Scope of the Problem

Substance use and a mental illness, alone or in combination, put people at high-risk for getting entangled in the legal system [3]. Already in their first episode of schizophrenia, 30% of patients have a substance use disorders (the exact percentage will vary with region and definition of substance use). Substance-misusing first-episode patients are typically young men, and they often have better premorbid social but poorer academic adjustment compared to their non-using counterparts [4]. In the Clinical Antipsychotic Trials of Intervention Effectiveness (CATIE) cohort, which is more representative of chronic patients, almost four in ten patients had a current substance use problem [5]. Lifetime rates of any substance use problem are even higher.

In the United States, alcohol and cannabis are the most common problems among patients with schizophrenia. Cocaine use, and, interestingly, hallucinogen use, occurs with some frequency as well, whereas, curiously, opiate misuse seems to be infrequent to almost nonexistent in typical community mental health centers. Know your particular epidemiologic situation (e.g., is methamphetamine or phencyclohexylpiperidine [PCP] use common in your community?) and the drug use patterns in your patient population (e.g., college students misusing prescription stimulants or party drugs, including ketamine).

Those with alcohol problems seem to have a worse prognosis because alcohol is quite simply a rather toxic substance if used excessively. It is interesting that despite the adverse consequences of drug use, patients with schizophrenia and drug use problems (other than alcohol) tend to look better with regard to negative symptoms, even though positive symptoms are exacerbated. This suggests some drugs either remedy a deficit (the “self-medication hypothesis”) or that drug use flags those patients who have a better prognosis because they are less biologically impaired; you have to be more “with it” to be able to obtain drugs. Many epidemiologic studies suggest that cannabis use is especially problematic as it may represent a risk factor for schizophrenia. Frequent premorbid cannabis use (i.e., more than 50 times) increases the risk for the development of schizophrenia by sixfold, for example [6]. This is seen as evidence that – in susceptible patients – cannabis can trigger psychosis (see Chap. 4 for a longer discussion of this important public health concern).

Drug use can have devastating effects on patients, families, and society. Other than the obvious social (e.g., homelessness, drug-related crimes), legal (i.e., arrests), financial (i.e., compounding poverty), and medical (e.g., human immunodeficiency virus [HIV] which can lead to patients being “triply diagnosed” with HIV, a drug problem, and a psychiatric disorder) problems from drug use, drugs can maintain or cause psychiatric symptoms, and drug use is an important factor in psychotic relapse. One consequence of drug use is poorer compliance with medical and psychiatric treatment of all its sequelae from poorly treated diseases. Violence is much more likely if there is drug use. Substance use is a potentially avoidable contributor to premature mortality in schizophrenia patients. Unfortunately, substance use starts early, around or often before a first-episode psychosis, and is a significant problem in young, first-episode patients (see Chap. 11).

Assessment

Given the prevalence of substance use in schizophrenia, screening all patients to detect substance use problems is important. All too often, significant substance use is either not recognized at all or its severity not acknowledged. Your interview needs to include careful probing for use of substances of all classes, past and current. Make sure you get collateral information and do not rely on self-report alone. In addition, a structured screening tool for substance use problems that is part of an initial patient evaluation facilitates its detection and treatment planning. I use the abbreviated Alcohol Use Disorders Identification Test for Consumption (AUDIT-C), for example, to screen all new patients for problems with alcohol use even though the tool was not specifically developed for use in schizophrenia populations; cutoffs in particular may not apply (even low-grade drinking can be problematic for some patients) [7]. I would argue that it does not matter so much which specific tool you use: using one tool consistently for all your patients is what matters most. Laboratory screening to help diagnose unrecognized problems is essential. Urine drug testing is one tool that can provide valuable information if its limitations (false-positive and false-negative results) and ramifications (legal difficulties) are also taken into account and openly discussed with a patient. Saliva drug testing for point-of-care use in the office and hair testing for drugs ingested in the previous 3 months are options to consider. Hair testing poses its own problems – depending on the hair style in fashion (you need a sufficient amount). For our profession, drug testing is never a tool to “catch patients” but ought to be seen as clinical information that can inform your treatment plan.

Diagnostically, you have two problems. First, it can be next to impossible to disentangle the contributions to psychopathology from the primary disorder and from substances. In many cases, however, the longitudinal history will eventually clarify the diagnoses (see Chap. 4 for a longer discussion). Second, patients with schizophrenia lead different lives, and the usual screening questions and diagnostic categories do not necessarily work well: if you never worked or if you never married, you cannot lose your job or your marriage over drinking.

Related posts:

Persecutory Delusional Disorder and Social Anxiety Psychosis and Clinical Staging Drug Interactions Nonmotor Side Effects Aspects of Schizophrenia Care

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