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