A study by Canadian researchers found that just three hours of therapy in a school setting can have lasting effects on reducing the incidences of mental health disorders in adolescents.

The study was designed to test whether researchers could train educators in schools to deliver early intervention programming to stop teens vulnerable to mental health disorders from turning to alcohol or illicit drugs.

Among 509 British 13-year-olds, researchers found that incidences of mental health issues were reduced by 25 to 33 per cent over two years following only two 90-minute group sessions facilitated by educators.

The trial, conducted by a team from the University of Montreal-affiliated Research Center of CHU Sainte-Justine, is one of several trials the team has conducted that look at teen brain development and psychology.

The students, from 19 schools in Greater London, signed on to participate in what the researchers call "coping skills workshops."

Based on personality assessments, students were grouped according to four self-described personality profiles: those who identified as impulsive or thrill-seeking, those prone to anxiety, and negative thinkers.

With guidance from an educator, the students were encouraged to discuss their emotions, thought patterns and triggers. After, they were asked to explore ways to manage their problems.

In the two years following the therapy sessions, researchers tracked the students' progress through regularly submitted questionnaires.

Researcher Dr. Patricia Conrod said the workshops provided vulnerable students with psychological interventions before "they even enter into situations" in which they would be offered drugs or alcohol.

"It was delivered early in their trajectory, before the onset of substance abuse, before mental health problems may begin to interfere with their social and cognitive development," Conrod, said in an interview with CTVNews.ca.

"By delivering interventions in a targeted way, you're able to do a lot more focused work in a shorter amount of time."

While the group sessions didn't necessarily produce positive results for all the students two years later, a broad spectrum of participants, were helped, Conrod said.