Story at a glance
- Seasonal affective disorder is a mood disorder characterized by depression that occurs at the same time every year.
- A new study suggests a potential link between seasonal conditions and the volume of the human brain.
- The study examined thousands of brain scans taken at a Connecticut hospital over 15 years.
The seasons rule much of our experience on Earth: the weather, length of the day, harvest, even religious and cultural practices. Now, evidence suggests that the size of your brain could also change with the colors on the trees.
After studying the brains of more than 3,000 people in Connecticut over 15 years, scientists found that the volume of the cerebellum, which is the part of the brain responsible for voluntary movements and motor skills, grew in the summer and shrank in the winter, while the subcortical structures, which are responsible for memory, emotion, pleasure and hormone production, did the opposite. These results were also more pronounced in female brains than male brains, the study found.
"Investigating these changes further may be informative for seasonal disorders or discover previously unknown seasonal effects on other diseases," researchers said, noting that about 5 percent of Americans experience seasonal affective disorder. The results could also have consequences for people who struggle with chronic headaches, which other studies have suggested could be influenced by weather.
Why does this happen? It's not clear, but the study does hazard a few guesses, including changing vitamin D levels and a change in blood flow. But there’s still much more research to be done, scientists say.
These preliminary results still leave a lot of questions unanswered, including how the changes in brain volume would vary if done in different parts of the world, where seasonal weather is different. It also didn't make many allowances for a range of other factors, including race, ethnicity, education, body mass index, medication, menstrual cycle, recreational drug use and smoking status.
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