Mental disorders are becoming a major public health problem in China, with a national survey suggesting about 17.5 percent of Chinese adults suffer different forms of mental disorders.

The survey also found rural residents suffer a higher prevalence of mental disorders than urban residents.

Mental disorders include mood disorders, anxiety disorders and substance abuse.

The survey was conducted by the Beijing Suicide Research and Prevention Center at Beijing Huilongguan Hospital and five other local institutions on mental disorder research in Zhejiang, Shandong, Qinghai and Gansu provinces.

It was based on interviews of 113 million respondents, covering 12 percent of all adults in the country above 18 years old in 96 cities and 267 rural areas of four provinces including Zhejiang, Shandong, Qinghai, and Gansu.

People above 40 years old have higher rates than people who are under 40, according to the survey.

Female adults suffered higher rates of mood disorder and anxiety disorder than men.

But for alcohol abuse, the rate among men is 38 times that among women, the survey showed.

According to the survey, people from different provinces suffer different forms of mental disorders due to their specific characters and local customs.

"In Gansu and Shandong provinces, people suffer severely from alcohol abuse since many of them really love to drink heavily due to their forthright and uninhibited nature," said Li Xianyun, director of the Beijing Suicide Research and Prevention Center at Beijing Huilongguan Hospital. Li said mental disorders have become a common public health issue. However, only a few people have realized the necessity of treatment.

The survey showed that less than 11 percent of people with mental disorders in Shandong have received treatment, and the rate is even lower in Qinghai, where only 3 percent went to hospital.

"Most people who have mental disorders may not even know it, and some even try to cover it up since they have been looked down upon by society for such a long time," she said. "This kind of situation occurs especially in developing countries, including China."

The survey lasted from 2001 to 2005 and was the third of its kind in China. The previous two were conducted in 1982 and 1993.

"Based on statistics from the research, policy makers in the public health sector will know the real reasons why many people with mental disorders have not received treatment in different provinces, such as in Qinghai, where only one hospital can provide treatment for mental disorders," Li said. "Building more hospitals and training more doctors are imminent."

"In most other provinces in China, helping people cast away misunderstanding toward mental disorders and getting disorders treated is the future task," she added.