Does coffee protect against Alzheimer's disease?

Hi there, coffee enthusiasts!

As a physician, I get asked a lot if coffee fits in a healthy lifestyle. Usually, I tell people that coffee will not harm your health when consumed in moderation. Since I work in the field of dementia, people often follow up by asking if it can help prevent Alzheimer’s disease.

In the current blog, we will address this question as research claims that coffee can help prevent Alzheimer’s disease.

Indeed, some studies have shown that associations exist between coffee consumption and lower rates of Alzheimer’s disease or cognitive decline for that matter (1-4). So should we all start drinking coffee more?

Unfortunately, it is a little more complicated than that. Let me try to explain. It is true that some researches have shown these associations. However, studies claiming the opposite also exist. So, which should you believe? My answer is both!

But how can both be true? The answer to that question lies in the nature of these studies. In research, it all comes down to how you approach the thing you want to study. For example, you can explore the history of dementia patients and examine whether (excessive) coffee consumptions co-occur and if this differs from non-demented individuals. You could also observe coffee drinkers over a long period of time and wait and see if they develop dementia. These types of experiments determine the reliability of your results. Therefore, both findings can be true, but the interpretation may be different.

So how reliable is the current evidence. Every study which has been done about this topic has a low to medium level of reliability. However, it seems there exist more evidence in favor of coffee and its protective effects than there is ‘negative’ evidence. Even though, it is low-level evidence, it does suggest a relationship may exist when these results pile up (the perfect experiment just hasn’t been executed yet).

Coming back to your question if you should drink more coffee. I would recommend to consume in moderation and try to drink a maximum of 4 cups a day. In addition to the accumulation of low-level evidence, the literature also states that the protective effects of coffee against dementia is dose dependent. And this dependency is not linear. This means that more coffee does not necessarily equal more protection.

In fact, when you consume too much coffee you are even ‘less protected’ than someone who doesn’t drink coffee at all!

Let’s take a look at figure below to visualize this. If you follow the brown line, you can see that your risk of cognitive decline lowers with higher coffee consumption up until a certain threshold. Above this threshold, your risk increases. This threshold is set around 3-4 cups a day.

In conclusion, there is definitely evidence that coffee up to 4 cups a day may have protective effects against Alzheimer’s disease and dementia. However, this evidence is not 100% verified and might be more nuanced in reality.

My advice: just keep drinking that lovely cup of coffee as long as you do it in moderation 😊

 References

1. Chen JQA, Scheltens P, Groot C, Ossenkoppele R. Associations Between Caffeine Consumption, Cognitive Decline, and Dementia: A Systematic Review. Journal of Alzheimer's Disease. 2020;78:1519-46.
2. Eskelinen MH, Ngandu T, Tuomilehto J, Soininen H, Kivipelto M. Midlife coffee and tea drinking and the risk of late-life dementia: a population-based CAIDE study. J Alzheimers Dis. 2009;16(1):85-91.
3. Zhang Y, Yang H, Li S, Li W-d, Wang Y. Consumption of coffee and tea and risk of developing stroke, dementia, and poststroke dementia: A cohort study in the UK Biobank. PLOS Medicine. 2021;18(11):e1003830.
4. Wasim S, Kukkar V, Awad VM, Sakhamuru S, Malik BH. Neuroprotective and neurodegenerative aspects of coffee and its active ingredients in view of scientific literature. Cureus. 2020;12(8).