NEW YORK – Teenagers who use cannabis, alcohol and nicotine are more likely to have underlying psychiatric symptoms, and worse symptoms, than their peers who are not regularly using substances, new research has found.

The research, published on Jan 29 in Jama Paediatrics, found that such substances are linked to an array of symptoms and conditions, including anxiety, depression, hyperactivity and suicidal ideation.

These findings suggest that asking adolescents about substance use may provide a powerful screening tool when looking for underlying mental health issues, researchers said.

“Universally screening for psychiatric symptoms in the context of all types of substance use is what we think might be most important,” said Assistant Professor Brenden Tervo-Clemmens, a psychiatry expert at the University of Minnesota and lead author of the paper.

“All the symptoms of mental health we examined, be it depression, suicidal thoughts, ADHD (attention-deficit hyperactivity disorder), were elevated no matter what the substance was,” he added.

The paper found that the link between substance use and mental health existed even at low levels of drug and alcohol use.

Asst Prof Tervo-Clemmens said adolescents with low levels of substance use may be self-medicating, and that their relatively modest substance use was not likely to be causing the underlying mental health challenges.

But the research also found that the most frequent and intensive users of the substances experienced the most severe mental health symptoms.

In these instances, Asst Prof Tervo-Clemmens said, the adolescents may be worsening their symptoms even as they use substances to self-medicate.

Specifically, the study found that daily or near-daily use – but not weekly or monthly use – of substances was linked to a moderate increase in symptoms.

Researchers described the connection as “dose dependent”, because the level of use was linked to the intensity of symptoms.

The strength of the study came from its use of two data sets that yielded similar findings.

One sample used survey data from 15,600 Massachusetts high school students, with a median age of around 16. The second sample drew on similarly self-reported data from 17,000 respondents to the national Youth Risk Behaviour Survey.

In both groups, the study’s authors noted, “alcohol, cannabis and nicotine use each had significant, moderate dose-dependent associations with worse psychiatric symptoms, including suicidal thoughts”.

Another key finding was that the link was present between multiple symptoms and between multiple substances.

“It’s not just cannabis, it’s not just alcohol, it’s not just nicotine,” Asst Prof Tervo-Clemmens said. “It seems to be, no matter the substance.”

Compared with prior generations, today’s adolescents are experiencing more mental health symptoms but a declining use of drugs and alcohol.

Binge-drinking and cigarette smoking, in particular, have fallen sharply, affecting a smaller portion of the adolescent population.

That is because the group of regular substance users is smaller than it once was and may be more closely linked to individuals who are self-medicating or otherwise dealing with mental health challenges. NYTIMES