Comorbidity of severe psychotic disorders with measures of substance use

Abstract

Importance: Although early mortality in severe psychiatric illness is linked to smoking and alcohol, to our knowledge, no studies have comprehensively characterized substance use behavior in severe psychotic illness. In particular, recent assessments of substance use in individuals with mental illness are based on population surveys that do not include individuals with severe psychotic illness.

Objective: To compare substance use in individuals with severe psychotic illness with substance use in the general population.

Design, setting, and participants: We assessed comorbidity between substance use and severe psychotic disorders in the Genomic Psychiatry Cohort. The Genomic Psychiatry Cohort is a clinically assessed, multiethnic sample consisting of 9142 individuals with the diagnosis of schizophrenia, bipolar disorder with psychotic features, or schizoaffective disorder, and 10,195 population control individuals.

Main outcomes and measures: Smoking (smoked >100 cigarettes in a lifetime), heavy alcohol use (>4 drinks/day), heavy marijuana use (>21 times of marijuana use/year), and recreational drug use.

Results: Relative to the general population, individuals with severe psychotic disorders have increased risks for smoking (odds ratio, 4.6; 95% CI, 4.3-4.9), heavy alcohol use (odds ratio, 4.0; 95% CI, 3.6-4.4), heavy marijuana use (odds ratio, 3.5; 95% CI, 3.2-3.7), and recreational drug use (odds ratio, 4.6; 95% CI, 4.3-5.0). All races/ethnicities (African American, Asian, European American, and Hispanic) and both sexes have greatly elevated risks for smoking and alcohol, marijuana, and drug use. Of specific concern, recent public health efforts that have successfully decreased smoking among individuals younger than age 30 years appear to have been ineffective among individuals with severe psychotic illness (interaction effect between age and severe mental illness on smoking initiation, P = 4.5 × 105).

Conclusions and relevance: In the largest assessment of substance use among individuals with severe psychotic illness to date, we found the odds of smoking and alcohol and other substance use to be dramatically higher than recent estimates of substance use in mild mental illness.

Figure 1

Frequency of alcohol (Figure 1A), smoking (Figure 1B), marijuana (Figure 1C) and other drug (Figure 1D) use contrasted among subgroups. Odds ratios correspond to odds of the prevalence of the symptom among cases with chronic psychotic illness versus controls. The OR's are contrasted with one another. When an OR is statistically different from the reference (European descent for ethnicity, male for gender, and 30-49 for age group), this is indicated by * (p<0.05) or ** (p<0.001).

Figure 1

Frequency of alcohol (Figure 1A), smoking (Figure 1B), marijuana (Figure 1C) and other drug (Figure 1D) use contrasted among subgroups. Odds ratios correspond to odds of the prevalence of the symptom among cases with chronic psychotic illness versus controls. The OR's are contrasted with one another. When an OR is statistically different from the reference (European descent for ethnicity, male for gender, and 30-49 for age group), this is indicated by * (p<0.05) or ** (p<0.001).

Figure 1

Frequency of alcohol (Figure 1A), smoking (Figure 1B), marijuana (Figure 1C) and other drug (Figure 1D) use contrasted among subgroups. Odds ratios correspond to odds of the prevalence of the symptom among cases with chronic psychotic illness versus controls. The OR's are contrasted with one another. When an OR is statistically different from the reference (European descent for ethnicity, male for gender, and 30-49 for age group), this is indicated by * (p<0.05) or ** (p<0.001).

Figure 1

Frequency of alcohol (Figure 1A), smoking (Figure 1B), marijuana (Figure 1C) and other drug (Figure 1D) use contrasted among subgroups. Odds ratios correspond to odds of the prevalence of the symptom among cases with chronic psychotic illness versus controls. The OR's are contrasted with one another. When an OR is statistically different from the reference (European descent for ethnicity, male for gender, and 30-49 for age group), this is indicated by * (p<0.05) or ** (p<0.001).