Seasonal plasticity of cognition and related biological measures in adults with and without Alzheimer disease

Seasonal plasticity of cognition and related biological measures in adults with and without Alzheimer disease

https://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.1002647

Abstract

Background

There are few data concerning the association between season and cognition and its neurobiological correlates in older persons—effects with important translational and therapeutic implications for the diagnosis and treatment of Alzheimer disease (AD). We aimed to measure these effects.

Methods and findings

We analyzed data from 3,353 participants from 3 observational community-based cohort studies of older persons (the Rush Memory and Aging Project [MAP], the Religious Orders Study [ROS], and the Minority Aging Research Study [MARS]) and 2 observational memory-clinic-based cohort studies (Centre de Neurologie Cognitive [CNC] study at Lariboisière Hospital and the Sunnybrook Dementia Study [SDS]). We performed neuropsychological testing and, in subsets of participants, evaluated cerebrospinal fluid AD biomarkers, standardized structured autopsy measures, and/or prefrontal cortex gene expression by RNA sequencing. We examined the association between season and these variables using nested multiple linear and logistic regression models. There was a robust association between season and cognition that was replicated in multiple cohorts (amplitude = 0.14 SD [a measure of the magnitude of seasonal variation relative to overall variability; 95% CI 0.07–0.23], p = 0.007, in the combined MAP, ROS, and MARS cohorts; amplitude = 0.50 SD [95% CI 0.07–0.66], p = 0.017, in the SDS cohort). Average composite global cognitive function was higher in the summer and fall compared to winter and spring, with the difference equivalent in cognitive effect to 4.8 years’ difference in age (95% CI 2.1–8.4, p = 0.002). Further, the odds of meeting criteria for mild cognitive impairment or dementia were higher in the winter and spring (odds ratio 1.31 [95% CI 1.10–1.57], p = 0.003). These results were robust against multiple potential confounders including depressive symptoms, sleep, physical activity, and thyroid status and persisted in cases with AD pathology. Moreover, season had a marked effect on cerebrospinal fluid Aβ 42 level (amplitude 0.30 SD [95% CI 0.10–0.64], p = 0.003), which peaked in the summer, and on the brain expression of 4 cognition-associated modules of co-expressed genes (m6: amplitude = 0.44 SD [95% CI 0.21–0.65], p = 0.0021; m13: amplitude = 0.46 SD [95% CI 0.27–0.76], p = 0.0009; m109: amplitude = 0.43 SD [95% CI 0.24–0.67], p = 0.0021; and m122: amplitude 0.46 SD [95% CI 0.20–0.71], p = 0.0012), which were in phase or anti-phase to the rhythms of cognition and which were in turn associated with binding sites for several seasonally rhythmic transcription factors including BCL11A, CTCF, EGR1, MEF2C, and THAP1. Limitations include the evaluation of each participant or sample once per annual cycle, reliance on self-report for measurement of environmental and behavioral factors, and potentially limited generalizability to individuals in equatorial regions or in the southern hemisphere.

Conclusions

Season has a clinically significant association with cognition and its neurobiological correlates in older adults with and without AD pathology. There may be value in increasing dementia-related clinical resources in the winter and early spring, when symptoms are likely to be most pronounced. Moreover, the persistence of robust seasonal plasticity in cognition and its neurobiological correlates, even in the context of concomitant AD pathology, suggests that targeting environmental or behavioral drivers of seasonal cognitive plasticity, or the key transcription factors and genes identified in this study as potentially mediating these effects, may allow us to substantially improve cognition in adults with and without AD.

My depression was somewhat related to SAD. However it was even more related to eating lots of carbs. Now it is almost non-existent though I do tend to slow down a bit in winter. I suspect a long time ago it may have been adaptive to stuff your face with carbs when they were available in autumn, then slow down both physically and mentally until the real food came back in spring.

I didn't know before that there was a seasonal effect to Alzheimers too.

It appear that seasons affect cognition and in some moods.

I know I always feel better as the daylength starts to visibly increase.

The strange thing is that some people get "reverse SAD" and are worse in summer. Maybe they spent a long time as cave people.

Some people have researched the effects of blue light to the extent they sell those blue-blocking glasses. I wonder what effect they would have on Alzheimers.

Chris said:
"Some people have researched the effects of blue light to the extent they sell those blue-blocking glasses. I wonder what effect they would have on Alzheimers."


In a 2017 post called "Blue Light May Help Alzheimer’s Patients "
It says "Now, Alzheimer’s patients may use a specific type of blue light to reset their internal clocks in order to sleep better."

more to read here
https://www.alzheimers.net/2014-02-24/blue-light-helps-alzheimers/

All the best Jan

Wow interesting!

Long ago I read something freaky - that the pineal gland is the original "third eye" and light can penetrate that far into the brain if it is strong enough. Don't know how true that is, but you can see light penetrating your hand if you hold it over your eyes while looking at the sun