How the seasons affect dementia and mental health

A new study suggests the seasons can affect mental health.

How the seasons affect dementia

How is your mind functioning this spring? If you experience sluggishness or mild cognitive impairment at certain times of the year, you’re not alone. A new study suggests that the memory and thinking abilities of healthy older adults declines over winter and early spring. It also suggests that we see an increase in cases of mild cognitive impairment and dementia during these seasons.

Dementia is a condition classified by a significant deterioration in memory and thinking ability (cognitive function). This deterioration can lead to a decline in a person’s ability to complete everyday tasks, such as staying oriented while running errands, paying a bill and experiencing rapid mood changes.

The study, conducted by researchers in the United States and Canada, aimed to find out whether seasons might influence poorer cognition in healthy adults, along with those with dementia. The research arose from previous findings, linking ‘seasonal affective disorder’ (seasonal-related depression) and first episodes of schizophrenia, which occurred during specific times of the year.

What the research found
The results of the study suggest that seasonal changes in a person’s psychological state could be influenced by stress and other social factors, which may correlate with seasonal trends.

The study involved 2700 healthy older adults from Chicago, and 500 people with dementia from Toronto, who were tested on their ability to retain information for a short time and process information quickly.

In activities such as memorising a phone number and ability to quickly perform a task (i.e. draw a clock on a piece of paper) participants performed better during summer and autumn than in other months. What’s more, the results didn’t change when the person’s moods, physical activeness, sleep quality, time of day or thyroid health were factored in.

The researchers concluded that these cognitive changes were linked more strongly with the season, and unlikely to be driven by environmental factors (i.e. lower physical activity in winter).

What should we take away?
While this study provides interesting insights into how seasons can affect cognitive function, further research is needed to make any solid claims.

In the study, participants were not followed during each season over a whole year. Rather, already-existing data was used to fill in the blanks.

Additionally, the results stem from Northern Hemisphere samples – and this may or may not be pertinent to the Southern Hemisphere.

Finally, on a large-scale reflection, it’s true the study suggests a trend of lowered cognitive performance and an increase in dementia cases during winter and early spring. However, further study is needed to make a strong case against this simply being evidence of ‘winter blues’.

Ultimately, what we can take away is that a greater awareness for the mental wellbeing of vulnerable people in our communities should be observed during certain times of the year. 

The results of this study were published in the journal PLOS Medicine. To read more, visit

Have you noticed changes in your cognitive function during particular seasons? If you’ve been diagnosed with dementia, did this occur during winter or early spring?



    To make a comment, please register or login
    26th Oct 2018
    It sounds like they only researched temperate climates and didn't even consider tropical heat and humidity.
    26th Oct 2018
    I can't see any particular places listed for the Southern Hemisphere either.
    Within Australia we have classifications of several different climates, tropical heat and humidity being one of them. People in those are less likely to be out and about as much, especially the elderly or asthmatics who don't cope well with that type of weather and are advised to stay indoors.

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