In middle-income countries, more people suffer from some kind of mental or neurological illness than infectious diseases or heart ailments. But these problems often go unrecognized and untreated. A new survey finds mental illness in China is more common than previously thought.

A recent study finds mental illness is more common in China than previously thought, and some who suffer from it have associated problems that don't conform exactly to Western definitions

Earlier studies in China had found between 1 and 9 percent of the population had some kind of mental disorder. But a new study in the British journal The Lancet found that the rate is closer to 17 percent. That's about the same rate as in the United States or Australia.

Substance abuse, mood and anxiety disorders were the most common in the study, which looked at 63 thousand people in both urban and rural China.

Only about 8 percent of those with mental illness actually sought help.

That's partly because there isn't much help available, says Lawrence Yang, a psychologist and epidemiologist at Columbia University in New York. He wrote an editorial accompanying the article in The Lancet.

"The provision of mental health services is a huge issue," he says. "Just to give you a sense of it, in urban China, they have major hospitals. But these only exist in large urban centers. So you have, in the rural areas, they have to travel very, very far. I mean, sometimes a day or days."

The authors of the study write that mental health has become better recognized in China over the last quarter century, but access to mental health care is lagging far behind.

Dr. Yang says one of the advantages of this study over earlier studies is that patients were examined by psychiatrists who knew the local culture. Earlier studies used standardized questionnaires given by unskilled health workers, which could have missed more subtle clues of mental illness. Interestingly, Dr. Yang says, about a quarter of the people in the study with mental illness had depression or anxiety or other problems that interfered with their lives, but didn't fit into the standard definitions. 

"This study highlights that there are cultural variants of depression and anxiety that we probably don't understand very well yet," he says.

He added that understanding those cultural differences in mental illness is one of the next frontiers of psychiatry.