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International study reveals mental disorders are leading cause of disability in young people worldwide

Lancet

The first study to provide a comprehensive picture of the global causes of disability in adolescence and to outline the main risk factors that emerge in these years and cause disease in later life, shows that neuropsychiatric disorders (mostly unipolar major depression, alcohol use, schizophrenia, and bipolar disorder), which are largely absent from public health programmes, are the leading cause of disability worldwide--representing 45% of the disease burden among young people aged 10󈞄 years. Furthermore, the key global risk factors that affect health in later life include alcohol use, unsafe sex, iron deficiency, and lack of contraception.

The findings published Online First in The Lancet, show that in this age group, the burden of disease is increasingly driven by conditions causing disability rather than death and highlight the need to focus on the prevention of, and health promotion against, non-communicable and non-fatal causes of disease in adolescence. According to the authors, these findings will be a challenge to the political willingness of key stakeholders to investment in prevention programmes that take many years to reveal their full effects (such as tobacco taxes, and human papillomavirus vaccination of adolescent girls).

Young people aged 10󈞄 years represent 27% (more than 1.8 billion) of the world's population and their number is set to rise to about 2 billion by 2032. Although important health problems and risk factors for disease in later life emerge during these years, because adolescence is generally thought to be a time of good health, opportunities for prevention of disease and injury have not been fully exploited.

Recent research has reported the global patterns of death in young people, but has not investigated the lifestyle risk factors that start during adolescence and can lead to future disability.

In this study, Fiona Gore from WHO, Geneva, Switzerland and colleagues used data from the 2004 Global Burden of Disease to estimate the cause-specific disability-adjusted life-years (DALYS) for young people aged 10-24 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 (YLLs) and Years Lost due to Disability (YLDs), with one DALY representing the loss of the equivalent of 1 year of full health.

Findings showed that total DALYs for people aged 10-24 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 15-19 years.

The three main causes of disability worldwide for both sexes were neuropsychiatric disorders (45%; mostly unipolar major depression, alcohol use, schizophrenia, and bipolar disorder), unintentional injuries (12%; mainly road traffic accidents), and infectious and parasitic diseases (10%).

The main global risk factors for future disability in all age groups (0-80 years) are underweight, unsafe sex, alcohol use, unclean water, poor sanitation and hygiene. In contrast, the research showed that the main health risks emerging during adolescence were alcohol use, unsafe sex, iron deficiency, and lack of contraception.

The authors say: "The 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, and overweight and obesity, their contribution to disease becomes apparent only in mid-to-late adulthood."

They conclude: "Our risk factor data suggest that preventive strategies should adopt a life-course approach whereby the focus on the adolescent and young-adult years is prominent."

In a Comment, John S Santelli and Sandro Galea from Columbia University, New York, USA say: Health promotion and efforts for disease prevention in young people aged 10-24 years should recognise both the burden of disease in this age group and the influence of risk behaviours on health in later life. Interventions should address the behaviours and social conditions that have both short-term and long-term health consequences. 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."

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Ms Fiona Gore from WHO, Geneva, Switzerland. T) +41 22 791 16 19 E) goref@who.int

Dr John S Santelli, Columbia University, New York, USA. T) +1 917 846 3288 (mobile) E) js2637@columbia.edu

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