OBJECTIVE: The study investigated whether contingency management could
reduce cocaine use by patients with schizophrenia. METHODS: An A-B-A
research design, with two-month baseline, intervention, and follow-up
phases, was used to study two homeless, treatment-resistant male
outpatients with DSM-III-R diagnoses of schizophrenia and cocaine
dependence. During the intervention phase, subjects provided daily urine
specimens for testing for the cocaine metabolite benzoylecgonine (BE) and
received $25 for each negative test. Concentrations of BE and metabolites
of other illicit drugs were assayed twice a week to determine the amount of
drug use in addition to frequency. Analysis of variance was used to compare
drug use during the three study phases. RESULTS: During the intervention,
the proportion of tests positive for cocaine was lower for both subjects.
Mean urinary concentrations of BE were significantly lower during the
intervention than during the baseline. CONCLUSIONS: These results suggest
that modest monetary reinforcement of abstinence may decrease cocaine use
among cocaine- dependent patients with schizophrenia.