The recent tragedy in Newtown, Connecticut, perpetrated by 20 year-old Adam Lanza, has intensified the discussion about how mental health is handled and documented in the US. Officials have not provided information about Lanza’s motivation and state of mind, and many are rightfully quick to point out that it is wrong to equate mental illness with the fatal sociopathic actions of a small group of individuals. The conversation about access to mental health care should, however, take into account new data showing an increasing contribution of mental and behavioral disorders to deterioration in the health-related quality of life among teenagers in the US and Canada over the last two decades, and increases elsewhere around the globe.

The estimation of ‘years lived with disabilities’, or YLDs, is used as a collective metric to determine how much a particular disorder deprives the population of healthy years of life during a particular window of time. In 2010 just as in 1990, depression ranked as the number two contributor of YLDs, affecting 4% of the global population, eclipsed only by back pain that affected almost 10% of population worldwide. Among 10 to 14 year olds, the top contributor worldwide is iron deficiency. Asthma had been the largest contributor to YLDs for youths in that age range in the US and Canada in 1990, but the study published in The Lancet on Thursday led by researchers at the Institute of Health Metrics and Evaluation (IHME) at the University of Washington in Seattle showed that depression surpassed asthma to claim the number one spot in this group in 2010. Among this cohort, the collective number of ‘years lost to disability’ grew from about 140,000 in 1990 to almost 180,000 in 2010, a 30% increase. Notably, global figures for the same age group show that the number of years lost to disability from depression grew from 4.9 million in 1990 to 5.5 million in 2010, a 13% increase as shown in the graphs below.

A question remains as to whether the change in numbers reflects an actual increase in children who develop depression, or better diagnosis, documentation and the way healthcare practitioners and policy makers view mental health now compared with 1990. “There is a good possibility that the rise in disease burden related to mental health in some regions is due to better diagnosis, at the same time, the magnitude of the rise in some areas should draw policymakers attention, as should the very high level of the burden from mental health problems across regions,” says Mohsen Naghavi, an author of the study and a health expert at IHME.

Whereas depression accounted for the most YLDs among adolescents, the disease burden from anxiety, schizophrenia and bipolar disorder in the US and Canada of all ages ranked 5, 10 and 18, respectively. By comparison, anxiety, schizophrenia and bipolar disorder ranked 7, 16 and 18, respectively, among the world population of all ages. “When you are seeing more years lived with disability from depression and anxiety than you are from most injuries, chronic diseases and infectious diseases, then you need to start thinking about addressing them by borrowing from lessons we have learned from those other areas or by innovating new tools,” Naghavi says.

Whereas we have learned a lot about mental disorders and their specific characteristics over the past 20 years, more work needs to be done in terms of care. “We haven’t done as good a job with improving care for depression and reducing its burden as we have for other conditions that were considered important in the 1990 estimates,” says Jurgen Unutzer, a psychiatrist and behavioral scientist at the University of Washington who was not involved in the study.

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