Dementia symptoms peak in winter, spring: Study

Dementia symptoms are more pronounced in the winter and spring, say scientists who found that people with and without Alzheimer's disease have better cognition skills in the late summer and early fall.

There have been few previous studies concerning the association between season and cognition in older adults.

The study, published in the journal PLOS Medicine, analysed data on 3,353 people who had undergone neuropsychological testing. For some participants, levels of proteins and genes associated with Alzheimer's disease were available.

Researchers from University of Toronto in Canada found that average cognitive functioning was higher in the summer and fall than the winter and spring, equivalent in cognitive effect to 4.8 years difference in age-related decline.

In addition, the odds of meeting the diagnostic criteria for mild cognitive impairment or dementia were higher in the winter and spring, than summer or fall.

The association between season and cognitive function remained significant even when the data was controlled for potential confounders, including depression, sleep, physical activity, and thyroid status.

Finally, an association with seasonality was also seen in levels of Alzheimer's-related proteins and genes in cerebrospinal fluid and the brain.

"There may be value in increasing dementia-related clinical resources in the winter and early spring when symptoms are likely to be most pronounced," researchers said.