If you’re feeling better now that spring is here, it’s not all in your head. A study led by San Diego State University Graduate School of Public Health research professor, John W. Ayers, links a number of major mental illnesses, disorders and problems to the seasons.
For some time, scientists have understood seasonal affective disorder (SAD), but new research by Ayers and his team — published today by the American Journal of Preventive Medicine — finds that Google searches for information about all major mental illnesses and problems follow seasonal patterns. This suggests mental illness may be more strongly linked with the seasons than previously thought.
Using Google’s public database of queries, the research team identified and monitored mental health searches in the United States and Australia from 2006 through 2010.
All searches relating to mental health were captured and then grouped by type of mental illness – including attention deficit hyperactivity disorder (ADHD), anxiety, bipolar disorder, depression, eating disorders such as anorexia or bulimia, obsessive-compulsive disorder (OCD), schizophrenia and suicidal ideation.
Identifying trends
Researchers used advanced mathematical methods to identify trends and found all mental health searches in both countries were consistently lower in summer than in winter. This pattern appeared to closely mirror the length of daylight according to the season.
The research showed eating disorder searches were down 37 percent in summers versus winters in the U.S., and 42 percent in summers in Australia. Schizophrenia searches decreased 37 percent during U.S. summers and by 36 percent in Australia.
Bipolar searches were down 16 percent during U.S. summers and 17 percent during Australian summers; ADHD searches decreased by 28 percent in the U.S and 31 percent in Australia during summertime. OCD searches were down 18 percent and 15 percent, and bipolar searches decreased by 18 percent and 16 percent, in the U.S. and Australia respectively.
“We didn’t expect to find similar winter peaks and summer troughs for queries involving every specific mental illness or problem we studied, however, the results consistently showed seasonal effects across all conditions ..."
Searches for suicide declined 24 and 29 percent during U.S. and Australian summers and anxiety searches had the smallest seasonal change — down 7 percent during U.S. summers and 15 percent during Australian summers.
While some conditions, such as seasonal affective disorder are known to be associated with seasonal weather patterns, the connections between seasons and a number of other major disorders was surprising to Dr. James Niels Rosenquist, a psychiatrist at Massachusetts General Hospital.
“We didn’t expect to find similar winter peaks and summer troughs for queries involving every specific mental illness or problem we studied, however, the results consistently showed seasonal effects across all conditions — even after adjusting for media trends,” said Rosenquist, a researcher on the study.
Historic challenge
Typically, telephone surveys are used to assess respondents, but this approach has a large margin of error because respondents may be reluctant to give honest answers about their mental health. This approach also has high material costs and as a result, investigators are not able to collect as much data as they need to assess seasonal patterns, especially for rare mental illness.
“Monitoring population mental illness trends has been an historic challenge for scientists and clinicians alike — the Internet is a game changer,” said Ayers, the lead investigator of the study.
“By passively monitoring how individuals search online we can figuratively look inside the heads of searchers to understand population mental health patterns.”
Broader potential
“It is very exciting to ponder the potential for a universal mental health emollient, like Vitamin D (a metabolite of sun exposure). But it will be years before our findings are linked to serious mental illness and then linked to mechanisms that may be included in treatment and prevention programs,” said Ayers.
“Is it biologic, environmental or social mechanisms explaining universal patterns in mental health information seeking? We don’t know.”
“Our findings can help researchers across the field of mental health generate additional new hypotheses while exploring other trends inexpensively in real-time,” said Benjamin Althouse, a doctoral candidate at Johns Hopkins Bloomberg School of Public Health and researcher on the study.
“For instance, moving forward, we can explore daily patterns in mental health information seeking … maybe even finding a ‘Monday effect.’ The potential is limitless.”
More information
Dr. Daniel Ford, vice dean for clinical investigation in the Johns Hopkins University School of Medicine, and Jon-Patrick Allem, doctoral student at University of Southern California Keck School of Medicine also contributed to the study.
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