Depression is the second most common cause of disability worldwide after back pain, according to a review of research. The disease must be treated as a global public health priority  , experts report in the journal PLOS Medicine. The study compared depression with more than 200 other diseases and injuries as a cause of disability. "Globally, only a small part of patients have opportunities to be treated," the World Health Organization (WHO) says. Depression was ranked at number two as a global cause of disability, but its effects varied in different countries and regions. For example, rates of major depression were highest in Afghanistan and lowest in Japan. In the UK, depression was ranked number three in terms of years when people lived with a disability. Dr Alize Ferrari from the University of Queensland's School of Population Health led the study.   "Depression is a big problem and we definitely need to pay more attention to it than we do now," she told BBC News. "There's still more work to be done in terms of awareness of the disease and also successful ways of treating it. The burden is different between countries, so the rate of depression tends to be higher in low and middle income countries and lower in high income countries." Policy-makers have made an effort to bring depression to the forefront, but there is still a lot more work to be done." "There're lots of confusions we know related to mental health," Prof. Alize Ferrari explained. "What one person recognizes as disabling might be different to another person and might be different across countries as well, there are lots of cultural effects and explanations that are related to depression, which makes it more important to raise awareness of the size of the problem and also signs and how to find depression." The data--for the year 2010--follows similar studies in 1990 and 2000 looking at the global burden of depression. Commenting on the study, Dr Daniel Chisholm, a health economist at the department of mental health and substance abuse   at the WHO said depression was a very disabling condition. "It's a big public health challenge and a big problem to be thought about but not enough is being done. Around the world only a tiny part of people get any sort of treatment or diagnosis." Dr Daniel Chisholm said. The WHO recently started a global mental health action plan to raise awareness of depression among policy-makers. Who is Alize Ferrari?
She is a doctor working in a hospital. She is a professor at a university leading the study. She is an official from the government. She is a common teacher taking part in the study.