Zheng used several large multinational datasets to examine changes in how people rated their health between 1981 and 2007 and compared that to medical expansion in 28 countries that are members of the Organization for Economic Co-operation and Development, an organization of countries, including the United States and many countries in Europe.

“Access to more medicine and medical care doesn’t really improve our subjective health," said Zheng. "For example, in the United States, the percentage of Americans reporting very good health decreased from 39 percent to 28 percent from 1982 to 2006."

One reason for the decline could be that more aggressive screening techniques have detected more diseases in more people, including “over diagnosis,” which Zheng says can be harmful to healthy people.

He also says the study suggests more diseases are discovered or “created,” which increases the risk of being diagnosed with new diseases, such as attention deficit hyperactivity disorder, depression and autism.

He conducted a “counterfactual analysis” to see what would have happened if the medical industry had not expanded at all in these countries since 1982 while other factors that are generally linked to improved health, such as economic development, were left unchanged.

The analysis predicted that people’s feelings about their own health would have increased, about 10 percent in the United States for example.

Zheng measured three kinds of medical expansion: medical investment, which includes health care spending per capita and total health employment; medical professionalization and specialization, including the number of practicing physicians and specialists; and expansion in the pharmaceutical industry, which includes pharmaceutical sales per capita.

The study appears in the July 2015 issue of the journal Social Science Research.