Mental health problems are common among adults who smoke cigarettes and those with substance use disorders, illustrating a need for treating smoking and mental health problems together, according to a new study by Indiana University.

The research, done in conjunction with other universities, found mental health problems were more than twice as common among adults with substance use disorder who smoke cigarettes compared to those without substance use disorder who do not smoke cigarettes.

"Our study shows that there is a need for consistency in treating mental health, smoking and substance use problems together," said Maria Parker, assistant professor at the IU School of Public Health-Bloomington and lead author of the study. "Smoking cessation does not undermine progress made in mental health or substance use treatment programs."

The study, published in Drug and Alcohol Dependence journal, used data from the United States National Survey on Drug Use and Health. The prevalence of mental health problems (i.e., serious psychological distress) was estimated over 10 years for adults who had current daily, current non-daily, former and never cigarette smoking by substance use disorder status.

Mental health problems continue to increase in the U.S. and is associated with negative health consequences including premature mortality and chronic health conditions.

"It is critical that we identify groups with higher prevalence of mental health problems that could be targeted for interventions," Parker said.

The study found serious psychological distress varied significantly by substance use disorder status and cigarette smoking status, such that serious psychological distress was between three and five times higher for those with substance use disorder compared to those without across all smoking statuses.

These patterns were found for nearly every sex, age, race/ethnicity, income and marital status subgroup. The prevalence of serious psychological distress was highest for those with substance use disorder and daily cigarette smoking, with a quarter or more of these adults reporting distress.

The study also found that serious psychological distress increased over time for all smoking statuses, and increases over time were higher for people with substance use disorder than those without.

Parker said to address cigarette smoking and substance use disorder for those with mental health problems, incorporating a broad psychiatric symptom assessment into cigarette smoking cessation or substance use disorder treatment programs may be beneficial. Additionally, when assessing and treating individuals for cigarette smoking and substance use disorder, providers might screen for psychiatric symptoms.