Drug Abuse in Schizophrenia and Bipolar Disorder

ABSTRACT

The incidence and type of drug abuse for 50 male schizophrenic patients and 60 male and female bipolar, manic patients were determined. Fifty percent of schizophrenic patients and 25% of bipolar patients abused one or more drugs. Alcohol, cannabis, and cocaine accounted for 82% of the drug abuse.

INTRODUCTION

In recent years the relationship between various psychiatric disorders and drug abuse has received increased attention[1-7]. Some workers have speculated that specific psychiatric disorders may predispose to specific drug abuse[8, 9]. Invariably drug abuse has been regarded as influencing negatively the course of the disease. In this study we documented the incidence and type of drug abuse in newly hospitalized bipolar, manic patients and in newly hospitalized schizophrenic patients in order to assess the similarities and differences between them.

The psychiatric inpatient records of 50 consecutively admitted male schizophrenic patients and 60 bipolar, manic patients (17 male and 43 female) were studied retrospectively. Patients were included if they met DSM-III-R Axis I criteria for schizophrenia, paranoid type or bipolar disorder, manic type, diagnosed by a senior attending psychiatrist, were at least 17 years of age and were not suffering from an Axis III diagnosis with the single exception of tardive dyskinesia.

Charts were reviewed to identify patients meeting DSM-III-R Axis I criteria for alcohol, opiate, cocaine, amphetamine, cannabis, hallucinogen, phencyclidine, sedative-hypnotic, and anxiolytic drug abuse. Data from the preadmission evaluation, the admitting office psychiatric history, the PGY II psychiatric history, the senior attending psychiatrist note, and the discharge summary were examined and correlated. In all cases the most extensive documentation of substance abuse was considered the most reliable. No patient was identified as a substance abuser by this method who had not been identified and diagnosed at the time of discharge from the index admission.

During the period of the study only 17 male patients met criteria for the DSM-III-R Axis I diagnosis of bipolar, manic type. Therefore female bipolar, manic patients were included. Age at the time of the index admission, race, marital status, employment status, number of prior psychiatric hospitalizations, and private versus public health insurance were determined for both groups.

Data were analyzed using means and SDs, and Student’s t test (two-tailed). Categorical data were analyzed using [Chi.sup.2] statistic.

RESULTS

Twenty-five of 50 male schizophrenic patients abused one or more drugs. Twelve (24%) abused alcohol, 13 (26%) abused cannabis, and 8 (16%) abused cocaine. Diazepam, psilocybin, phencyclidine, amphetamine, and codeine were each abused by one patient. Ten patients abused more than one drug. Alcohol-cannabis combinations accounted for two, cocaine-cannabis accounted for four, cocaine-amphetamine accounted for one, cocaine-cannabis-phencyclidine accounted for one, cocaine-cannabis-psilocybin accounted for one, and alcohol-cocaine-opiate accounted for one. While 25% of alcohol-abusing schizoprenic patients combined alcohol with another drug, 61% of cannabis abusers and 100% of cocaine abusers did so. These differences are significant (df = 2, [Chi.sup.2] = 11.2, p [is less than] .01).

Fifteen of 60 bipolar manic patients (4 of 17 males and 11 of 43 females) abused one or more drugs. Eleven (18%) abused alcohol, five (8%) abused cannabis, six (10%) abused cocaine, and three (5%) abused opiates. Benzodiazepines and phencyclidine were each abused by two patients. Six patients abused more than one drug. Alcohol-cocaine-cannabis combinations accounted for two, opiate-cocaine-cannabis-phencyclidine accounted for one, alcohol-cocaine-opiate-benzodiazepine accounted for one, alcohol-cocaine-cannabis-phencyclidine accounted for one, and alcohol-cocaine-benzodiazepine accounted for one. While 45% of alcohol-abusing bipolar patients combined alcohol with another drug, 80% of cannabis abusers and 100% of cocaine abusers did so. These differences approached significance (df = 2, [Chi.sup.2] = 5.74, p [is less than] .06). When the alcohol use data for schizophrenic and bipolar patients was pooled, the tendency for alcohol to be used alone was evident. While 33% of alcohol-abusing schizophrenic and bipolar patients combined alcohol with other drugs, 66% of cannabis abusers and 100% of cocaine abusers did so. These differences are significant (df = 2, [Chi.sup.2] = 16, p [is less than] .001).

Although apparent, differences in drug use between the schizophrenic and bipolar cohorts were not analyzed. Examination of demographic and clinical variables revealed that the cohorts were significantly different on measures of age, gender, and marital and employment status (Table 1), and, therefore, not comparable.

DISCUSSION

There are several methodological limitations in the design of this study which should be noted. The study is retrospective and naturalistic, and depends upon observations made by clinicians and not by researchers employing standardized diagnostic assessment instruments. The sensitivity, validity, and reliability of retrospective substance abuse diagnoses are difficult to assess. The most extensive documentation of substance abuse was presumed the most reliable, but the possibility remains that the patient or interviewer provided an exaggerated report.