(HealthDay News) — When the seasons change, immune system response may also change, which might explain why conditions such as rheumatoid arthritis and cardiovascular disease are worse in the winter than in the summer, according to a study published online May 12 in Nature Communications.
The researchers from the University of Cambridge in the United Kingdom analyzed genes from more than 16,000 people worldwide, including those from both the Northern and Southern hemispheres. They found that the activity of nearly one-quarter of the genes differed according to the time of the year. Some are more active in winter and some are more active in summer, the research revealed. Seasons also affect immune cells, and the composition of blood and fat, according to the study.
One gene that was more active in the summer and less active in the winter has been shown to suppress inflammation in mice. If the same is true in people, those in the Northern Hemisphere would have higher levels of inflammation in the winter. The researchers also found that certain genes associated with people’s responses to vaccines were more active in winter. This means that some vaccination programs might be more effective during that season.
“In some ways, it’s obvious – it helps explain why so many diseases, from heart disease to mental illness, are much worse in the winter months – but no one had appreciated the extent to which this actually occurred,” John Todd, professor and director of the JDRF/Wellcome Trust Diabetes and Inflammation Laboratory at the University of Cambridge, said in a university news release. “The implications for how we treat disease like type 1 diabetes, and even how we plan our research studies, could be profound.”