Researchers at Washington University School of Medicine in St. Louis and University of Southern California conducted the largest assessment of substance use among people with psychiatric illnesses. They found that rates of smoking, drinking, and drug use are considerably higher among those with psychotic disorders compared to the general population.

Published in the journal JAMA Psychiatry, the finding is of particular concern because individuals with severe mental illness are more likely to die younger than people without psychiatric disorders.

Lead researcher Sarah M. Hartz, MD, PhD, from Washington University School of Medicine says, “These patients tend to pass away much younger, with estimates ranging from 12 to 25 years earlier than individuals in the general population. They don’t die from drug overdoses or commit suicide — the kinds of things you might suspect in severe psychiatric illness. They die from heart disease and cancer, problems caused by chronic alcohol and tobacco use.”

Hartz also says 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.”

The study assessed smoking, drinking, and drug use in nearly 20,000 participants. 9,142 of the participants had psychiatric disorders like schizophrenia, bipolar disorder, or schizoaffective disorder — an illness categorized by psychotic symptoms like hallucinations and delusions, and mood disorders such as depression.

75 percent of the participants with mental illness were regular smokers, compared to 33 percent of the individuals with no mental illness (the control group). Similarly, half of the people with psychotic disorders used marijuana regularly compared to 18 percent of the control group. Lastly, half of than participants with a mental illness also used other recreational drugs compared to 12 percent of the control group.

“I take care of a lot of patients with severe mental illness, many of whom are sick enough that they are on disability,” said Hartz. “And it’s always surprising when I encounter a patient who doesn’t smoke or hasn’t used drugs or had alcohol problems.”

Dr. Hartz noted that once a person develops a psychotic disorder, protective factors like race and gender do not have their usual influence. It has been known from previous research that Hispanics and Asians tend to have lower rates of substance abuse than European Americans. Also, women tend to gravitate less toward recreational substances than men.

“We see protective effects in these subpopulations,” Hartz clarified. “But once a person has a severe mental illness that seems to trump everything.”

Smoking among individuals with no psychiatric disorders range from 40 percent, for those over the age of 50, to 20 percent, for individuals under the age of 30; however, the smoking rate among the mentally ill is more than 75 percent, regardless of age. “With public health efforts, we’ve effectively cut smoking rates in half in healthy people, but in the severely mentally ill, we haven’t made a dent at all,” she said.

Hartz believes health professionals who treat the mentally ill must do better in trying to get them to stop substance abuse.