More threads by David Baxter PhD

David Baxter PhD

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Alcohol and cannabis use in schizophrenia explored
By Liam Davenport
14 January 2008
J Clin Psychiatry 2007; 68: 1939-1945

Alcohol use is linked to positive symptoms among first-episode schizophrenia-spectrum patients, potentially due to self medication, while cannabis use correlates with reduced negative symptoms, which may be due to the minimize drug-seeking behaviors, suggest US scientists.

Previous studies have shown that concurrent substance abuse is extremely common in patients diagnosed with schizophrenia and related psychotic disorders, with alcohol the most common substance misused. However, research into the nature of any associations between substance abuse and psychotic symptoms has yielded conflicting results.

Michael Compton, from Emory School of Medicine in Atlanta, Georgia, and colleagues therefore conducted a retrospective chart review of 72 patients aged 18-40 years. All of the patients were African American and had been admitted for a first episode of psychosis to a university-affiliated hospital that serves a socially disadvantaged, urban population.

The team used discharge summaries from 2002-2005 to collate data on basic demographic and clinical characteristics, the presence of 11 psychotic symptoms, and alcohol and cannabis use for the previous 6 months.

The average age of the patients was 23.4 years, and the average length of hospital stay was 15.9 days, ranging from 3-55 days. In all, 44.4% were diagnosed with schizophreniform disorder, 31.9% with paranoid type schizophrenia, 6.9% with undifferentiated type schizophrenia, 1.4% with catatonic type schizophrenia, 4.2% with schizoaffective disorder, and 11.1% with otherwise unspecified psychosis.

Alcohol had been used in the past 6 months by 36.1% of the patients, while 48.6% had used cannabis. Interestingly, 27.8% of the group had used both alcohol and cannabis whereas 43.1% had used neither alcohol nor cannabis in the previous 6 months.

Patients who had used alcohol were significantly more likely to exhibit positive aggressive symptoms, specifically auditory hallucinations, visual hallucinations, delusions, paranoia, and homocidal ideation, than those who had not used alcohol,. Cannabis users were significantly less likely to have prominent negative symptoms than patients who did not use cannabis.

Logistic regression analysis revealed that independent predictors of alcohol use were cannabis use, auditory hallucinations, visual hallucinations, and paranoia, while those for cannabis use were gender, alcohol use, and negative symptoms.

The team concludes in the Journal of Clinical Psychiatry: "The association between positive psychotic symptoms and alcohol use could be consistent with a self-medication hypothesis, although the association is likely multi-determined."

Discussing the explanations for the link between cannabis and reduced negative symptoms, they add: "Prominent negative symptoms cause motivational and hedonic effects that would interfere with drive and desire to obtain and use cannabis."

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