How Temperature Affects Cognition
It’s hard to remember more atypical circumstances. In my own life, I can’t recall such a freakish winter storm as the one I’m experiencing while I’m typing these words. Single digit temps, blankets of snowfall, frozen pipes, power outages lasting days, everything closed (Walmart too) – in South Central Texas?
In truth, I love the cold and the serenity of looking out to see the still, white majesty of an overnight snowfall. Winter’s the time when I feel energetic, curious, refreshed. Yet I fully understand why others disagree and will “take the heat” over a chilly day, hands- down.
But what does the brain say?
Is SAD Real?
SAD stands for Seasonal Affective Disorder, a type of depression that's related to changes in seasons. It begins and ends at about the same times every year. The assumption is that for most people who experience SAD, symptoms start in the fall and continue into the winter months, draining energy and increasing irritability. That makes for a lot of grouchy, depressed folks in January.
But research refutes the SAD theory as a general truth and notes that cold impacts us differently. In a large-scale study published in the journal Clinical Psychological Science, researchers found no evidence of any kind that symptoms of depression tend to be higher in winter — or at any other time of year. This study factored in geographical latitude and sunlight exposure on the day of the survey were also unrelated to depression scores.
Another study published in the journal Proceedings of the National Academy of the Sciences found that in younger populations experiencing normal levels of cold for winter, the brain actually works more efficiently than any other time of year. The study tested participants vigilance and working memory as well as other indicators of cognitive performance. The participants sense of alertness, their emotional state and melatonin levels didn’t vary with the seasons and their performance on tasks was largely the same.
In older populations, however, a study published in the journal Plos Medicine found that memory and cognitive performance were at their worst in spring and winter. They also concluded that diagnosing new cases of dementia and mild cognitive impairment were 30% more likely during these seasons.
Does this suggest SAD is age-related? If so, I can look forward to becoming a crabby old lady in winter.
Cold V. Hot
Sorry, summer lovers. When brain function is compared during different seasons, cold looks like the winner for being easier on the brain.
Studies show that hot weather is harder on cognitive function because of heat’s effect on glucose consumption. Like all organs, the brain requires energy to function produced by burning glucose. Generally, temperature regulation is more difficult in heat than in cold and the body needs more glucose in maintaining homeostasis when it’s hot outside. That means fewer energy resources for the brain resulting in problems with mental clarity and decision-making.
For the elderly, higher temperatures may increase the risk of mental disorders. One study analyzed data on emergency admissions related to mental diseases and daily temperatures over a period of more than 10 years in 6 different cities. The results indicated that high temperatures might threaten mental health and exacerbate symptoms of mental diseases. According to the results, more than 30% of admissions for anxiety were attributed to hot temperatures. Researchers postulate that exposure to hot temperatures brings reactions in the body that may cause an increase in stress hormone levels and brain temperature. Extremely hot weather, representative of a Texas summer day, may meddle with levels of serotonin and dopamine, the happy neuro-regulators that bring one a sense of well-being. No surprise that we’re snapping at one another in August.
Of course, no matter the weather, the principles of brain health stay consistent. Get some exercise, lay off the sweets, challenge your brain with new tasks rather than Netflix-bingeing from the couch. Go out and help a neighbor who needs food, clearing a driveway or repairing a burst pipe. Bundle up and marvel at the force of nature. Make plans for a sunnier day.
Studies cited in this blog:
https://journals.sagepub.com/doi/abs/10.1177/2167702615615867
https://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.1002647#pmed.1002647.ref002
Lee, S., Lee, H., Myung, W., Kim, E.J., Kim, H. (2018) Mental disease-related emergency admissions attributable to hot temperatures. The Science of Total Environment.616-617: 688-694. doi: 10.1016/j.scitotenv.2017.10.260