October 31, 2018
Memory and thinking skills may vary by season for people with Alzheimer’s disease, according to a new report. Investigators found that during the summer and fall, the brain appeared to be nearly five years “younger” than during the winter and spring.
The findings could have implications for testing and care of those with Alzheimer’s and other forms of dementia, as well as those suspected of having the disease.
Someone suspected of having Alzheimer’s disease might, for example, do worse on memory screening tests and hence be more likely to get a diagnosis of Alzheimer’s during the winter than in the summer. Better understanding of seasonal variations in cognitive skills could also have implications for clinical trials of new drugs for Alzheimer’s disease, as researchers should take monthly and seasonal variations into account when assessing results. Often, clinical studies of Alzheimer’s disease take many months, if not years, to be completed.
Family members caring for a loved one with Alzheimer’s might also need extra help during the cold 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,” said researcher Andrew Lim, from Sunnybrook Health Sciences Center and the University of Toronto.
For the study researchers looked at 3,353 older men and women living in the United States, Canada and France. All were over 70 and part of larger ongoing studies. About a quarter of them had Alzheimer’s disease.
Participants underwent tests of memory and thinking skills. Some were tested as well for the presence of biological markers tied to Alzheimer’s.
The researchers found that overall, cognitive functioning tended to be higher in the summer and fall compared to the winter and spring. The variation was equivalent to a 4.8 years difference in terms of age-related memory decline.
People were more likely to meet the diagnostic criteria for Alzheimer’s disease or mild cognitive impairment, a brain disorder that often leads to full-blown Alzheimer’s, in the winter or spring. Levels of proteins in the spinal fluid that correlate with Alzheimer’s disease were also higher in the winter months.
The researchers considered various conditions that may lead to memory and thinking problems, including depression, sleep problems, thyroid disease and levels of physical activity. The seasonal variations persisted even when these factors were ruled out.
Scientists aren’t sure why seasonal variations in cognition may occur, though light temperature, and hormone fluctuations as well as changes in diet, exercise habits and mood during the warmer months may play a role. Further research into the possible causes of seasonal variations in memory and thinking skills could lead to new and more effective ways to boost cognition in those with dementia, the researchers say.
By ALZinfo.org, The Alzheimer’s Information Site. Reviewed by Marc Flajolet, Ph.D., Fisher Center for Alzheimer’s Research Foundation at The Rockefeller University.
Source: Andrew S.P. Lim, Chris Gaiteri, Lei Yu, et al: “Seasonal plasticity of cognition and related biological measures in adults with and without Alzheimer disease: Analysis of multiple cohorts. PLoS Medicine Volume15(9, September 2018.