Between 1990 to 2019, Alzheimer's disease increased worldwide especially among elderly populations. Notably, women were at a higher risk for the disease, but the risk in men showed a faster increase13. By 2050 it is estimated that there will be 152 million people with Alzheimer's disease and other dementias13. However, in Europe there appears to have been a slight decline in dementia since 2008 in both men and women, but AD remains an issue with over 10 million people affected14-16 and it is predicted these rates will increase significantly. It is also suggested that women are disproportionately affected by dementia15.
Coffee, caffeine and risk of Alzheimer’s disease
The majority of studies suggest that moderate and regular coffee/caffeine consumption is associated with a reduced risk of developing AD17. However, some studies do show varying results.
- A 2017 review concluded that moderate coffee consumption may lower the risk for common neurodegenerative conditions including AD. However, the authors concluded that methodological differences in studies mean comparisons and conclusions can be difficult to reach, therefore further research is required 18.
- However, a 2018 meta-analysis of prospective studies that focused on Alzheimer’s disease revealed no association between coffee consumption and AD. The relative risk of Alzheimer’s disease for every 1 cup per day increment of coffee consumption was 1.0111.
- A 2022 review suggests that caffeine may be neuroprotective against dementia and possibly AD, but further studies are required to prove this link. The authors suggest that caffeine may be a cognitive normaliser and not a cognitive enhancer, and that gender may influence the neuroprotective effect of caffeine4.
- Additionally a 2017 theoretical review suggested an association between genetically predicted higher coffee consumption and higher odds of AD, however the role of genetic polymorphisms in diet and AD warrants further investigation 19.
Mechanism of action
A 2021 review suggested that methylxanthines, such as caffeine, are considered to act as antagonists of the adenosine receptor or as antioxidants. In turn they are believed to modulate molecular mechanisms associated with neurodegenerative diseases like the accumulation of misfolded proteins; oxidative stress and neuroinflammation20.
One hypothesis suggests that the modulation of adenosine receptors, namely the A2A receptor, affords neuroprotection through the control of neuroinflammation, but further work is required to explore this hypothesis 21.
Additionally, a 2021 review of bioactives in coffee suggested potential roles for other coffee compounds, including trigonelline, chlorogenic acid and caffeic acid, with further research required to confirm any associations22.