Substance use ‘dramatically’ high in severe psychosis

By Eleanor McDermid, Senior medwireNews Reporter

Patients with severe psychotic disorders have a risk for smoking, heavy alcohol use, and other drug use that “far exceeds” that documented in patients with mild mental illness, shows a large study.

The findings also suggest that “public health efforts to reduce substance use have not been successful in one of our most vulnerable populations, individuals with severe psychotic illness,” say lead researcher Sarah Hartz (Washington University School of Medicine, St Louis, Missouri, USA) and team.

The researchers assessed 9142 patients in the Genomic Psychiatry Cohort with a diagnosis of schizophrenia, bipolar disorder with psychotic features, or schizoaffective disorder. They say that such individuals are hard to contact for population-based surveys, so the rate of drug use is unknown.

The team found that “the prevalence of substance use in severe psychosis has been underestimated and spans social and cultural strata.”

Relative to 10,195 mentally healthy controls, the likelihood for drug or heavy alcohol use was elevated about fourfold after accounting for age, gender, and race, and this increased risk was present across all diagnoses. For example, the rates of heavy drinking (>four drinks/day) were 28% in schizophrenia patients versus 8% in controls. Also, 74% versus 33% reported ever smoking, 43% versus 18% used marijuana more than 21 times per year, and 35% versus 12% had used recreational drugs more than 10 times.

The highest risk was for daily smoking, which the researchers highlight “because most of the mortality seen in severe psychiatric illness is due to smoking-related disorders.” They add that public health measures to reduce smoking seem to have been ineffective in patients with psychotic disorders; among controls participants, smoking was less common in those younger than 30 years, but this was not seen in younger patients, who had an 8.2-fold increased risk for daily smoking relative to controls of the same age.

“The most striking finding of this study was the evidence that societal-level protective effects do not extend to individuals with severe mental illness,” write Hartz et al in JAMA Psychiatry.

Indeed, groups that normally have the lowest rates of substance use, such as women and people of Hispanic or Asian ethnicity, had the most increased risks relative to controls in this study. In women, for example, the risk for heavy drinking was elevated 6.1-fold relative to controls, whereas men had a smaller 3.5-fold increase.

“This highlights the need for targeting substance use specifically among individuals with severe psychotic illness because protective influences may not carry over from the general population,” the team concludes.

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