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Depression has become the leading cause of ill health and disability across the world, now affecting more than 300 million people globally, the World Health Organization said Thursday. However, half of people suffering from depression don't get treatments they need to live healthy, productive lives.

The worldwide depression rates increased 18 percent between 2005 and 2015, according to the WHO. Yet, there still exists a stigma associated with the condition, as well as a lack of support in many countries for those suffering from mental disorders. "These new figures are a wake-up call for all countries to re-think their approaches to mental health and to treat it with the urgency that it deserves," WHO director-general Dr. Margaret Chan said in a statement.

If helping out their fellow man doesn't convince health leaders to take depression seriously, doing so would also make economic sense, according to the WHO. Only 3 percent of government health budgets on average goes toward mental health, with the figure dipping to less than one percent in low-income countries, and up to just 5 percent in high-income areas. And yet, for every $1 USD invested in increasing depression and anxiety treatment, countries would see returns of $4 USD, because of better health and increased ability to work. Failure to adequately address depression can lead to financial loss for families, employers, and governments alike, the WHO noted.