John W. Ayers of San Diego State University, Benjamin Althouse of the Santa Fe Institute and colleagues examined Americans' Google search patterns and discovered during the recent Great Recession, people searched considerably more frequently for information about health ailments such as ulcers, headaches and back pain.
In total, the research team found there were more than 200 million excess queries of this kind during the Great Recession than expected, Ayers said.
"While it's impossible to uncover the motives for increased searches, they likely indicate a person being ill, and ill enough to seek out online information or remedies," Ayers said in a statement.
The research team previously published a report showing queries for anxiety and depression also increased substantially during the Great Recession.
The researchers used five root words indicative of the most common health problems: chest, headache, heart, pain and stomach and controlling for search terms that might return false positives such as "tool chest."
The researchers measured how frequently people in the United States searched for queries involving those root terms during the Great Recession, defined as December 2008 through 2011, and came up with a list of 343 symptom queries.
The team calculated what the search volume of those symptoms' queries would have been if there had been no Great Recession -- what statisticians call synthetic controls -- correcting for such variables as the growing availability of the Internet and increased usage.
The study, published in the American Journal of Preventive Medicine, found searches for stomach ulcer symptoms were 228 percent higher than would be expected and headache symptoms were 193 percent higher, representing about 1.48 and 1.52 million excess searches.
The study also found several broad categories of health concerns stuck out: Queries about headaches were 41 percent higher than expected; hernias, 37 percent; for chest pain, 35 percent; and for heart arrhythmias, 32 percent.
The project was supported by a Google.org grant from 2012, although Google.org played no role in designing or conducting this study, the researchers said.