Seasonal Fluctuation in the Cognitive Skill of Elderly People
The cognitive skills of elderly people (geriatric population) appear to rise and fall with the seasons, according to a research study released recently in the journal PLOS Medication.
Specifically, the study discovered that older people who took cognitive tests throughout winter and early spring had the tendency to have lower scores– particularly for tasks including working memory and perceptual speed– than those who took the tests at other times of the year.
The research study likewise found that when the elderly do cognitive testing in winter and spring, they are significantly more likely to meet the diagnosis of mild cognitive impairment than if they took the tests in summertime or early fall. Mild cognitive impairment is mired in controversy. Some academics say this condition is a possible precursor to the advancement of dementia.
“Cognitive function normally declines with age, and the seasonal difference we found is roughly equivalent to four years of aging. This means that an older person functioned as if they were four years older in the winter, compared to how they functioned in the summer.”
For the research, De Jager and his team examined data collected from a string of cognitive tests conducted on 2,761 healthy older adults and 592 dementia patients. The patients originated from diverse pool of racial and ethnic groups living in the United States, Canada and France. Most of them were above 70 years of age.
The individuals went through the testing on a single day, but those days were scattered throughout the year. When the researchers compared the screening dates with the outcomes, they found that individuals tested in July through October scored better, typically, than those tested in the other months.
Undoubtedly, the scientists found that ratings tended to peak around the fall equinox in late September.
These findings was true for both the healthy adults and those detected with Alzheimer’s disease, although the seasonal differences were smaller among those with dementia.
The two cognitive abilities most impacted by the seasons were working memory (the capability to hold information in the mind for a brief time, such as while memorizing a pin number) and perceptual speed (the time it requires to acknowledge or compare signs or figures or to do other simple tasks).
The seasonal association was so “robust,” state the scientists, that the individuals’ ratings were 30 percent more most likely to fulfill the diagnostic criteria for mild cognitive impairment when the tests were taken in the winter and spring than in the summer season and fall.
Overall, the average decline in cognitive operating observed throughout winter and early spring was about the exact same as if the individuals had actually aged by 4.8 years, the researchers concluded.
These findings held even after adjusting for possible confounding aspects, such as the time of day the test was administered and the participants’ mood, self-reported hours of sleep and exercise, and thyroid health. (Some research study suggests that levels of thyroid hormones can impact cognition even in individuals who have actually not been identified with a thyroid condition.)
The scientists also examined the spinal fluid drawn from some of the participants in the study who were diagnosed with dementia, as well as the autopsied brains of participants who had passed away.
In those samples they discovered more proof of seasonal rhythms, particularly in the levels of Alzheimer-disease-related proteins in the spine fluid and in the expression of dementia-related genes in the brain.
What might be driving these seasonal effects is uncertain. It might be environmental aspects, such as light and temperature, De Jager and his co-authors write. Or it might be cognition-impacting factors that had not been controlled for in the study, such as older people being more socially isolated throughout the winter season or having winter season related injuries or pain. (The symptoms of rheumatoid arthritis, for example, tend to intensify when weather turns cold and moist).
Limitations and ramifications
The study does have its caveats. To start with, it is an observational study, so it can reveal only a connection in between cognitive function and the changing seasons, not a cause-and-effect relationship. In addition, the participants were only tested once. They weren’t repeatedly assessed throughout the year to figure out if their cognitive skills altered with the seasons.
Another limitation is that the research study included individuals living only in temperate environments of the Northern Hemisphere. It is not a worldwide study, of participants living in climatic conditions where wide differences are seen in temperatures between the winter and summer months. The results might have been different if it had included individuals from warmer climates with less seasonal variation.
Still, this study’s crucial finding– that season may be related to cognitive function– is not that improbable. As background details provided in the paper explains, we already know that seasonal rhythms modulate human behavior and physiology, including brain functions. Individuals with seasonal affective disorder (SAD), for instance, experience a distinct drop in their mood throughout late fall and winter season. Research study has likewise found that the onset of schizophrenia symptoms is more likely to happen in late summer season.
The existing research study suggests that “researchers may need to take the time of year into account when measuring how diseases like Alzheimer’s develop over time, and there may be a need for additional care and support provision in the winter months but we need to see more work to be sure of these findings.”
But for individuals, the implications of the research study’s findings are less clear.
The outcomes of this research study do not suggest we ought to all rush to book sunlight breaks over the winter season.
While there is no sure-fire way to prevent dementia, research has highlighted things we can do to lower our threat of the condition, including regular work outs, frequently, balanced diet, healthy weight, avoidance of smoking, and keeping blood pressure and cholesterol in check.