Psychological problems are also an emerging risk, not only for the health of the middle-aged, but also the younger generation. In South China's Guangzhou, the capital of Guangdong province, the incidence of major psychosis has tripled in the past decade, according to the Guangzhou Association of Mental Health.

Zhao Zhenhuan, general secretary of the association, said that in the decade between 2000 and 2010, mental illnesses were usually discovered between the ages of 18 and 30. "Now the problem occurs in people aged 16 to 25," he said.

In the first three month of this year, nearly half of the 1,000 calls received by the Shanghai 24-hour Hotline for Psychological Crisis Intervention were made by people aged 25 to 40, most of whom were white-collar workers.

"Those people are in the most stressful period of their lives. They are taking the responsibility of caring for both their parents and their children, and are also subjected to great pressure at work, meaning they may be more susceptible to psychological crises," Zhao said.

He said that more than 80 percent of Chinese people who displayed symptoms of depression never ask for professional assistance, and that nearly 90 percent of patients in hospitals across China have moderate or severe depression.

"People can adjust their psychological state, but without treating the condition effectively at an early stage, the problem may develop into a severe issue," he said.

Lack of research

At present, there is no national epidemiological investigation into the diseases, including cancers, diabetes, and heart diseases, that have become the major causes of death among the middle-aged group and directly affect life expectancy.

"There's a lack of such research because it costs a lot of money and human resources and so isn't economically viable in the short term. But it takes a huge toll on people's health and will cost the country's medical services a lot of money in the years to come," said Wan Weiqing, a physician at Beijing Tiantan Hospital.

For example, if the average incidence age for a certain disease is known to be 60, based on the epidemiological investigations, and the cost of a diagnostic test is very high, doctors may be reluctant to suggest to young patients that they should undergo it.

However, the results of epidemiological investigations can be a reliable guide to the formulation of a disease-prevention policy, according to Wan. "The more we know about the epidemiological rules of a certain disease, the better able we will be to treat it at an early stage," he said.

Wan suggested that people should take preventative measures long before they reach middle age. "Exercise is a good safety valve to release the tensions that build up at work. Don't let a bad mood control you for a long time. Rather, learn to control your mood and live a better, healthier life," he said.

Contact the writer at yangwanli@chinadaily.com.cn