Scott Drevs, 52, doesn’t just feel it in his bones when winter is coming—he feels it in his brain. Drevs has frontotemporal dementia, a rare form of dementia marked by changes in personality and trouble understanding and using language. Drevs can always tell when winter is on the way. “It feels like I want to hibernate,” said Drevs, who feels an increase in symptoms like brain fog, agitation, low energy and mood from Labor Day to Memorial Day.
Drevs lives in Green Bay, Wisconsin, where the temperature dips to a low of 39 degrees in October and doesn’t usually creep back up until May. In January, the low is an average of 9 degrees. Day length in the winter is about nine hours and the average snowfall is 13 inches in both December and January. It makes for bleak conditions for someone with dementia.
“It’s hard to be motivated to do anything,” said Drevs. “Even leaving the house is a challenge. One winter the neighbors came over to check on me because they didn’t notice any movement or lights going on and off.”
But it’s not just people with dementia that experience a change in cognition in the winter; a new study shows that older adults without cognitive disease experience a dip in brain power during the winter months. If you lose a glove at the grocery store or forget your scarf at home, can you blame it on ‘winter brain’?
“Season affects many aspects of human biology including human brain biology,” wrote the study authors in the journal PLOS Medicine.
Study authors from the U.S., Canada and France looked at 3,353 people from Chicago and Toronto who took cognitive tests and had their spinal fluid measured for Alzheimer’s disease related proteins. Their brains were sharpest in early fall and summer, but in winter, performance dipped.
And the effect of colder weather and drearier days didn’t result in just forgetting an item from the grocery list. For some study participants, the effect was significant enough that they changed from scoring in the normal range on a cognitive test to qualifying for a dementia diagnosis. In fact, study authors found a 31 percent greater chance of meeting criteria for mild cognitive impairment or dementia when tests were given during winter. The difference in cognition was equal to almost five years of cognitive decline that would happen normally as a person ages.
It wasn’t just the cognitive tests that changed in winter; researchers also measured higher levels of Alzheimer’s proteins and genes in cerebrospinal fluid.
Findings remained the same even when researchers accounted for the person’s mood, level of physical activity, sleep quality or the time of day of testing. That means the factors that go hand in hand with winter—like being cooped up inside or lower levels of activity—aren’t likely behind the drop in cognition.
The findings are limited because they only included data from Chicago and Canada. The same might not apply to those in the Southern Hemisphere. And the participants weren’t followed specifically for this study; researchers drew on readily available data. Participants were only tested once per year, and the study was correlational—meaning there was an association between winter and lower cognitive performance and Alzheimer’s-related proteins, but a direct cause can’t be concluded.
What the findings do suggest is that communities should be aware that dementia patients may be more vulnerable during the winter months.
“There may be value in increasing dementia-related clinical resources in the winter and early spring when symptoms are likely to be most pronounced,” the authors said. “By shedding light on the mechanisms underlying the seasonal improvement in cognition in the summer and early fall, these findings also open the door to new avenues of treatment for Alzheimer’s disease.”