Cocaine-induced psychosis and schizophrenia.
You are working in an emergency department. A patient presents in an acutely psychotic state, but his urine drug screen is positive for cocaine. You have no prior records or knowledge of the patient.
Is it possible to differentiate between cocaine-induced psychosis and schizophrenia?
We performed a Medline search combining cocaine and "psychotic, psychosis, delusion, or hallucination."
Patients in inpatient rehabilitation for uncomplicated cocaine dependence were asked about a spectrum of cocaine effects (Neuropsychopharmacology 1997;16:77-82). Although the sample size was unknown, researchers in a follow-up study found that about one-half of the patients in the sample developed brief paranoid delusional episodes that were intense enough to influence their behavior. For example, these patients checked locks, hid, or armed themselves (Am. J. Addict. 2004;13:305-15).
Nineteen patients with amphetamine- or cocaine-induced psychosis were recruited from a psychiatric emergency service. Interviews occurred, on average, 58 hours after last drug use (Am. J. Addict. 2000;9:28-37). Patients were evaluated, in part, using the Positive and Negative Syndrome Scale (PANSS). Positive symptoms corresponded to the 95th percentile of schizophrenic norms, and negative symptoms corresponded to the 17th percentile. The thought disturbance and anergia symptom clusters corresponded to the 80th and 25th percentiles, respectively. All subjects had paranoid delusions; 89% had referential delusions, 53% had grandiose delusions, 32% had somatic delusions, 95% had bizarre delusions, 95% had auditory hallucinations, 68% had visual hallucinations, 26% had tactile hallucinations, 26% had olfactory hallucinations, and 63% had Schneiderian forms of hallucination (such as hearing running commentary or two or more voices conversing with each other). One patient had gustatory hallucinations.
In another study, 54 patients with schizophrenia without current substance abuse (SZ), 30 cocaine-abusing patients without schizophrenia (CA), and 32 cocaine-abusing schizophrenia patients (CA+SZ) were selected from patients entering psychiatric emergency services at Bellevue Hospital in New York (Schizophr. Bull. 1999:25:387-94). Subjects were evaluated, in part, using the Schedule for the Assessment of Positive Symptoms (SAPS) and Schedule for the Assessment of Negative Symptoms (SANS).
In a comparison of SAPS scores, the ratio of the SZ group's mean total to the CA group's was 2.2:1, with the presence of thought disorder in the SZ group accounting for most of the difference (4.3:1). The ratio of the two groups' mean total SANS scores was 1.6:1, with the presence of alogia and flat affect accounting for most of the difference (2.0:1 and 1.4:1, respectively).
Over a 2-year period, 988 patients were examined at an inpatient psychiatric unit in New York (Schizophr. Bull. 1997;23:187-93). Study subjects suffered with either substance-induced psychosis (about 50% of these subjects used cocaine) or schizophrenia. The authors found that formal thought disorder and bizarre delusions significantly predicted the diagnosis of schizophrenia (odds ratios of 3.55:1 and 6.09:1, respectively).
Psychotic phenomenology was compared between 35 cocaine-dependent patients and 16 acutely psychotic schizophrenia patients who had not abused substances within the past year (Clin. Neuropharmacol. 1994;17:359-69). The authors found that certain first-rank Schneiderian symptoms were more commonly observed in patients with schizophrenia, including delusions of control and thought broadcasting. Thought insertion and thought withdrawal were not experienced in this sample of cocaine-dependent patients, but were experienced by patients suffering with schizophrenia.
The subjective psychotic phenomena of 18 patients who had recently used cocaine and 18 patients with schizophrenia were compared in another study (Psychopathology 1992;25:71-8). The authors found that certain phenomena--such as increased intensity of colors, increased vividness of objects, macropsia, micropsia, and transient paranoia--were specific to the cocaine-induced psychotic state.
Investigators examined the experience of cocaine-induced psychosis in 55 individuals diagnosed with cocaine dependence (J. Clin. Psychiatry 1991;52:509-12). Subjects with primary psychotic disorders were excluded. Of these 55 patients, 90% experienced transient paranoid delusions, mostly directly related to drug use (such as delusions of being followed or surrounded by law-enforcement personnel or by people wanting to steal their drugs); 83% experienced auditory hallucinations, which is often consistent with paranoid delusions; 38% experienced visual hallucinations (such as people following them or looking in windows); 21% experienced tactile hallucinations (such as bugs or foreign objects on the skin); and 27% experienced transient behavioral stereotypies. Only 3 of 55 subjects reported delusions or hallucinations that were not specifically about drug use.
Many of these studies were limited by sample size, but the available evidence challenges the notion that cocaine-induced psychosis is indistinguishable from schizophrenia.
DR. LEARD-HANSSON is a forensic psychiatrist affiliated with Atascadero (Calif.) State Hospital. DR. GUTTMACHER is chief of psychiatry at the Rochester (N.Y.) Psychiatric Center. They can be reached at email@example.com.
BY JAN LEARD-HANSSON, M.D.
BY LAURENCE GUTTMACHER, M.D.