More than 3 million people in the world suffer from depression, according to the World Health Organization.
This year's World Health Day aims to bring attention to a sickness the WHO says costs the global economy almost a trillion dollars in lost productivity - and causes a lot of misery.
In Turkey, the Ministry of Health says the use of anti-depressants has increased by about 70 percent in the past five years.
And like the rest of the world, the most at risk are young adults and the elderly.
TRT World’s Andrew Hopkins reports from Istanbul.