Symptoms of mental illness in children and adolescents do not appear to be increasing, according to a large study of Canadian youth published in CMAJ (Canadian Medical Association Journal)

"Popular media tends to perpetuate the idea that the prevalence of mental disorders is increasing," writes Dr. Ian Colman, Canada Research Chair in Mental Health Epidemiology and associate professor at the University of Ottawa, Ottawa, Ontario, with coauthors. "However, research supporting this position has been inconsistent."

Dr. Colman and colleagues sought to better understand whether symptoms of mental illness are increasing, specifically hyperactivity, aggression, depression and anxiety, suicidal thinking and behaviour. They looked at data from the National Longitudinal Survey of Children and Youth, which involves a group of children and adolescents from across the country who are followed every two years. Their study included 11 725 children aged 10-11 years (1994/95-2004/05), 10 574 aged 12-13 years (1996/97-2006/07) and 9835 aged 14-15 years (1998/99-2008/09). Participants were asked by confidential questionnaire to describe their feelings and behaviours and the frequency at which they experienced them in the previous week.

Some trends:

Depression and anxiety: mean symptom scores did not change significantly in children aged 10-11 years and 12-13 years.

There was a small but statistically significant decline in depression and anxiety in adolescents aged 14-15.

Physical aggression and indirect aggression such as antisocial or manipulative behaviour declined in all three age groups.

Suicidal behaviour: a decline in the percentage of youth aged 12-13 and 14-15 years who reported or attempted suicide.

Hyperactivity increased significantly in children aged 10-11 and 12-13 years.

"Encouragingly, results from this study suggest that suicidal ideation and suicide attempts may be declining," write the authors.

The authors suggest that perceptions of increases in prevalence of mental illness may be a result of successful efforts to destigmatize mental illness, which can lead to increased recognition of symptoms and treatment-seeking behaviour.

"Though there is no conclusive evidence for the efficacy of various efforts in preventing suicide, some strategies, including physician education and certain school-based strategies, show promise in reducing suicidal behaviours. Continued effort in suicide prevention, rigorous research into the efficacy of prevention programs, and improved interventions targeting mental illness in adolescents is crucial for improving the mental health of Canadian adolescents," they conclude.