Mental Disorders Leading Cause of Disability in World's Youth

Caroline Cassels

June 07, 2011

June 7, 2011 — Major depression, alcohol use, schizophrenia, and bipolar disorder are the main causes of disability worldwide among young people — accounting for almost half of the disease burden in this population, new research by investigators at the World Health Organization (WHO) shows.

A large study published online June 7 in The Lancet reveals that across the globe these disorders account for 45% of the disease burden among youth aged 10 to 24 years.

According to the study, young people aged 10 to 24 years represent 27% of the world's population. Although important health problems and risk factors for disease in later life emerge in these years, the contribution of the global burden of disease is unknown.

Although recent research has reported global patterns of death in young people, the study authors note there has been no investigation of lifestyle factors that start in adolescence and can lead to future disability.

"This is the first systematic description of global disease burden arising during adolescence and young adulthood...It provides the most complete overview until now of disease burden for this age group and is seen as complementary to Patton and colleagues' 2009 paper, which provided an overview of global mortality patterns," the study authors, led by Fiona M. Gore, MSc, write.

Risk Factors Rise in Late Adolescence

To describe the global burden of disease arising in young people and the contribution of risk factors to that burden, the investigators used data from the Global Burden of Disease to estimate the cause-specific disability-adjusted life-years (DALYs) for young people aged 10 to 24 years and to describe the contribution of the key global and regional risk factors for the burden of disease.

DALYs are a combined measure of years of life lost due to premature deaths and years lost to disability, with 1 DALY representing the loss of the equivalent of 1 year of full health.

The study showed that total DALYs for people aged 10 to 24 years were about 236 million, representing 15.5% of total DALYS for all age groups. Africa had the highest all-cause rate of DALYs, which was 2.5 times higher than in high-income countries. Across all regions, the disease burden was 12% higher in girls than in boys aged 15 to 19 years.

At a total of 45%, the main causes of disability worldwide for both sexes were neuropsychiatric disorders, including unipolar major depression, alcohol use, schizophrenia, and bipolar disorder. These were followed by unintentional injuries (12%), and infectious and parasitic diseases (10%).

The investigators also report the main global risk factors for future disability in all age groups (0 to 80 years) are underweight, unsafe sex, alcohol use, unclean water, and poor sanitation and hygiene. The main risk factors in adolescence were alcohol used, unsafe sex, iron deficiency, and lack of contraception.

The study authors point out that "disease burden arising in early adolescence from major risk factors is low. However, rates rise sharply in late adolescence and early adulthood for both alcohol use and unsafe sex. For other risk factors that commonly start in adolescence, such as tobacco use, low physical activity, high blood pressure, overweight, and obesity, their contribution to disease become apparent only in mid-to-late adulthood," the investigators write.

They call for preventive strategies that "adopt a life-course approach whereby the focus on the adolescent and young adult years is prominent.

Consider Long-Term Health

In an accompanying comment, John S Santelli, MD, MPH, and Sandro Galea, MD, DrPH, Columbia University, New York City, said the study provides new risk estimates for global disease burden in young people.

"This work is important in generating data for health status by region and national income and by age of young people and for identifying leading risk factors for incident DALYs...," they write.

They add that any health promotion and disease prevention efforts should take into account the burden of disease in this population and consider the influences of risk behaviors on long-term health.

"Interventions that increase resilience — eg, efforts for increasing the connections of adolescents to communities, schools, and families — are crucial for health promotion in young people. Furthermore, targeted public health interventions, including enforcement of seatbelt laws, redesign of cars, implementation of tobacco taxes, and distribution of condoms, are essential for reducing morbidity and mortality," they write.

The study authors have disclosed no relevant financial relationships.


Comments on Medscape are moderated and should be professional in tone and on topic. You must declare any conflicts of interest related to your comments and responses. Please see our Commenting Guide for further information. We reserve the right to remove posts at our sole discretion.