Brief reportInvestigating the use of contingency management in the treatment of cocaine abuse among individuals with schizophrenia: a feasibility study
Introduction
Substance abuse is common among persons with schizophrenia, with some estimates suggesting that as many as 47% have abused drugs (Regier et al., 1990). Estimates further suggest that 17–27% of patients with schizophrenia have abused cocaine (Shaner et al., 1993). Drug use by persons with schizophrenia is associated with a number of undesirable outcomes, such as poor compliance with medication and treatment regimens, and increased utilization of emergency services. This represents a significant public health problem (Shaner et al., 1999).
One of the most effective interventions available for treating cocaine abuse among persons without schizophrenia is voucher-based reinforcement therapy (VBRT), a type of contingency-management intervention wherein vouchers, redeemable for goods or services, are provided for abstaining from cocaine (Higgins and Silvennan, 1999, Petry, 2000). A growing body of literature suggests that cocaine abuse by patients with schizophrenia might also be amenable to treatment with VBRT. For instance, Tidey and colleagues have demonstrated that the substance use of persons with schizophrenia is maintained, at least in part, by the same factors that maintain substance use in individuals without schizophrenia (Tidey et al., 1999a, Tidey et al., 1999b). Furthermore, several groups have demonstrated that drug use by persons with schizophrenia can be reduced in VBRT analogs using cash as an alternative reinforcer to vouchers (cocaine: Shaner et al., 1997; cigarette smoking: Roll et al., 1998; marijuana: Sigmon et al., 1998).
The present study was conducted strictly as a feasibility study to ascertain if a VBRT program, using vouchers instead of cash, would be effective in reducing cocaine use in persons with schizophrenia. This is important because research suggests that cash and vouchers are not always equally effective in controlling drug use (Reilly et al., 2000). The provision of cash also raises ethical issues for some clinicians who believe it is likely to trigger a relapse to drug use by virtue of the association between cash and drug use. Furthermore, we wanted to examine the unique contributions of VBRT to abstinence, so this initial experiment was conducted without the provision of any other psychosocial treatment focusing on the participant's substance abuse.
Section snippets
Participants
Three male African–American Veterans (aged 41, 49 and 53 years) who had been referred to the study by their case managers participated in this study. All three had a primary diagnosis of schizophrenia, had been abusing cocaine (primarily ‘crack’) for more than 3 years, and were stabilized on individualized antipsychotic medication regimens. None of the three had any source of legal income other than their disability income. All were judged competent to provide informed consent by a licensed
Results and discussion
As can be seen by inspection of Fig. 1, there was a decrease in cocaine use during the intervention period relative to the two baseline periods. This decrease is approximately the same magnitude as that reported by Shaner et al. (1997) when they used cash as a reinforcer for cocaine abstinence in two individuals with schizophrenia. Although the decreases in cocaine use were modest, they represent clinically significant periods of abstinence, especially when it is recalled that each
Acknowledgements
This work was supported by Joe Young Sr. funds for biomedical research and the National Institute on Drug Abuse (DA 13941-02). The authors gratefully acknowledge the assistance of Drs C.R. Schuster and J. Grabowski as well as the staff at the John D. Dingell Veterans Administration Medical Center.
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