Dementia protection through coffee?
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A large prospective cohort study has shown that the consumption of caffeinated coffee and tea could reduce the risk of dementia. This only required 2.5-4.5 cups of coffee a day. According to the German Neurological Society, there are certainly plausible explanations for this observed effect, although the society also emphasizes that this is not controlled randomized data, but an observational study.
The underlying hypothesis of the current study was that the consumption of caffeinated coffee or tea is associated with a lower risk of dementia and better cognitive function. Data from the "Nurses' Health Study" (NHS) and the "Health Professionals Follow-up Study" (HPFS) were analyzed, in which the participants were prospectively followed up for 43 years. During this period, repeated surveys of dietary habits and cognitive status (subjective and objective) were carried out, including examinations for dementia. "This alone sets the new study apart from others in which dietary habits were only recorded at the beginning and which often only had a short follow-up period," explains DGN Secretary General Prof. Dr. Peter Berlit. The patients were also selected with the necessary care: not only people with previous illnesses such as tumors, Parkinson's disease or dementia were excluded, but also those who provided implausible information on their daily calorie intake and thus proved to be unreliable in documenting their dietary habits on the questionnaires.
A total of 86,606 female participants from the NHS cohort and 45,215 male participants from the HPFS cohort were included in the analysis. Of the 131,821 people, 11,033 developed dementia during the follow-up. The study participants were divided into quantiles according to their coffee consumption and then statistically analyzed to determine which quantile was associated with the lowest incidence of dementia. Two multivariate models were used to ensure data robustness. Model 1 adjusted for demographic characteristics, family history and total energy intake (the latter to account for differences in body size and metabolic efficiency, among others). Model 2 adjusted for lifestyle factors, diet quality, social factors and clinical comorbidities.
In the top quartile, women consumed an average of 4.5 cups per day (1 cup was defined as 237 ml of caffeinated coffee or tea) and men 2.5 cups per day. In the lowest quartile no coffee or tea was consumed, in the second quartile 0.43 cups (women and men) and in the third quartile 2.5 cups (women) and 1.25 cups (men).
The results showed that higher coffee consumption was associated with a significantly lower risk of dementia (141 vs. 330 cases per 100,000 person-years when comparing the fourth [highest] quartile with the first [lowest] quartile; this corresponds to a hazard ratio (HR) of 0.82 [95% CI, 0.76 to 0.89]). There was also a lower prevalence of subjective cognitive impairment (7.8% versus 9.5%; HR 0.85 [95% CI, 0.78 to 0.93]). "This means that those who drank caffeinated coffee were able to reduce their risk of dementia by 18%, which would certainly be a significant effect," emphasizes Prof. Berlit. Caffeine-free drinks (coffee or tea), on the other hand, had no protective effect.
But is such an effect plausible? What explanations are there for a possible dementia-protective effect of coffee? According to the authors, this could be due to various mechanisms:
- Caffeine reduces beta-amyloid (Aβ) deposits in the brain. Experimental studies have shown that caffeine lowers Aβ levels, suppresses β- and γ-secretase activity, improves neuronal plasticity and stimulates mitochondrial function and other signaling pathways.
- In addition, caffeine can lower proinflammatory cytokines in the brain and reduce neuroinflammation as a driver of cognitive decline. In addition to caffeine, coffee and tea also contain bioactive compounds such as polyphenols, chlorogenic acid and catechins, which reduce oxidative stress and improve cerebrovascular function.
- Caffeine's ability to improve insulin sensitivity and reduce the risk of type 2 diabetes could also contribute to its protective effect on cognitive health.
The results of the study are therefore physiologically plausible, emphasizes Prof. Berlit. "However, this is only observational data, even if the study is of very high quality."
Note: This article has been translated using a computer system without human intervention. LUMITOS offers these automatic translations to present a wider range of current news. Since this article has been translated with automatic translation, it is possible that it contains errors in vocabulary, syntax or grammar. The original article in German can be found here.
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