It is not something to be taken lightly. Left untreated it can kill as quickly as a physically debilitating disease. Liu Zhihua takes a closer look at depression.

It is more than just feeling low all the time. Depression can kill you. "I choose to die because I have depression. No particular reason. No big deal, and bye-bye." These were the final words a depressed college student in Nanjing posted on her weibo, or micro blog, before taking her own life.

Depression is a mental disorder that causes a constant feeling of sadness, helplessness and apathy paired with physical symptoms such as sleeplessness and psychosomatic or physical pain. It inflicts great suffering - so much so that in extreme cases, patients may finally commit suicide.

The estimated number of Chinese suffering depression is about 26 million to 30 million, but many of them have not been diagnosed, according to Chen Lin, director of the depression ward with Beijing Huilongguan Hospital, a famous mental health institution in the capital.

"Public awareness and knowledge of the condition have improved to some extent in the past decades, but it is not enough," Chen says. "Patients may have no idea they are suffering from depression. Even doctors in general hospitals may not recognize the symptoms."

A study by the World Health Organization indicates that the diagnosis rate of patients with depression in Shanghai is only 21 percent, much lower than the international ration of 55.6 percent.

Even worse, Chen adds, those who are diagnosed may not have access to treatment, because of the lack of medical resources.

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