February 18, 2026
By Dr. K S Parthasarathy
Somewhere between your morning coffee and your evening tea, please read what a group of very serious scientists has quietly confirmed. This is probably what every Indian household has known since the invention of the tumbler! Life runs on caffeine, and the brain apparently agrees! I am unable to understand how this morning coffee and evening tea itself started as a daily ritual in many Indian homes particularly so in South India. I gratefully recall that I drank the best coffee decades ago when my friend V G R Subramanian took me to a small eatery he used to visit as a student in Tirunelveli. VGR’s nostalgia and the aroma of the dicoction still linger on!
On 9 February 2026. JAMA (Journal of the American Medical Association) published the study by Yu Zhang et al., titled “Coffee and Tea Intake, Dementia Risk, and Cognitive Function”, on line. The researchers analyzed data from over 131,000 U.S. adults (86,606 women from the Nurses Health Study and 45,215 men from the Health Professionals Follow-up Study) followed for up to 43 years.
This paper is an eye opener for science communicators and researchers in this field. Thirteen scientists mainly from various departments of the Harvard University carried out this massive, long term, humongous study to unravel what cofee and tea does to human brain!
Before this study was published, evidence linking coffee and tea to cognitive health remained inconclusive, and most studies fail to differentiate caffeinated from decaffeinated coffee. The researcher’s objective was to investigate associations of coffee and tea intake with dementia risk and cognitive function. Now they claim that they conclusively showed that greater consumption of caffeinated coffee and tea was associated with lower risk of dementia and modestly better cognitive function, with the most pronounced association at moderate intake levels. After reading the crirical appraisal of the paper by ten scientists from the UK my conclusion is MORE RESEARCH IS NEEDED!
Let me invite researchers in the field to read experts comments at this link: (My apologies for including the comments of some experts in my article.
Key FindingsReduced Dementia* Risk: Higher intake of caffeinated coffee was associated with an 18% lower risk of developing dementia compared to those with the lowest intake.
Optimal “Sweet Spot”: The strongest protective associations were observed at moderate levels:2 to 3 cups of caffeinated coffee per day.
1 to 2 cups of caffeinated tea per day.
Caffeine as a Key Factor: The benefits were specifically linked to caffeinated beverages; decaffeinated coffee showed no significant association with lower dementia risk or improved cognitive function.
Cognitive Function: Caffeinated beverage intake was also linked to lower prevalence of subjective cognitivedecline (perceived memory or thinking issues) and modestly better performance on objective cognitive tests.
Genetic Risk: The protective association remained consistent regardless of whether participants had a high or low genetic predisposition for Alzheimer’s disease
*Dementia is a progressive syndrome involving a decline in cognitive function—memory, thinking, and behavior—that interferes with daily life, primarily affecting older adults.
While these results are significant, the authors and experts emphasize that this is an observational study showing an association, not direct causation.
This is certainly not a miracle cure. Not a “drink this and become Einstein.” suggestion either! Just a gentle scientific nod that your daily cup may be doing more than keeping you awake during Zoom calls.
What are the highlights?
Caffeinated coffee: Good for the brain.
(Your doctor may or maynot agree, but your brain apparently won the argument.)
Tea: Also, good. Especially if consumed with the solemnity of a 4 pm ritual.
Decaffeinated coffee: No benefit. (Frankly, even the scientists looked confused. “Why would anyone drink this?” was not written in the paper, but you can sense the emotion.)
What happens in real life? If you’re the one type who says, “Don’t talk to me until I’ve had my coffee,” congratulations—you may have been practicing preventive neurology without knowing it. If you are a tea person, sipping thoughtfully while staring out of the window, you too are on the right track. (Extra points if you swirl the cup like a philosopher.)
But here’s the middle-column twist (I forgot mine is not a middle column piece,though the topis is worth only that!)
Of course, this doesn’t mean you should drink seven cups daily and blame JAMA when you can’t sleep. Again, let me remind you, as in all habits, moderation is the key. Even the brain likes its caffeine in reasonable doses—like a good Malayalam movie: not too long, not too loud, just right.
What is the final word?
So, tomorrow morning, when you lift that cup, do it with pride. You are not just drinking coffee or tea. You are participating in a long-term cognitive wellness program—self-administered, culturally approved, and now scientifically validated/ endorsed
Expert reaction to the study (These comments are from a Science Media Centre Press release)
Most of the experts lauded the study as well designed and well conducted with large numbers of subjests.
Dr Mohammad Talaei, Lecturer in Life Course Epidemiology, Queen Mary University London (QUML) said: “The paper reports a robust association, supported by strong methodological approaches, leveraging the exceptional advantages of these American longitudinal studies: large sample sizes, long follow-up, and, most importantly, repeated assessments of lifestyle factors at later stages of the life course. Interestingly, they not only showed a lower risk of dementia but also modestly better cognitive function, as assessed by subjective and objective measures. However, there are two major considerations in this study:
“1. Dementia has a long prodromal phase, and, as the authors have mentioned, reverse causation is a concern. It means that a decline in coffee drinking or reporting coffee drinking could be a consequence of cognitive decline rather than the assumption that exposure precedes outcome. They have done a 4-year lag analysis, which is insufficient given the long prodromal phase of dementia, but also a 12-year lag analysis that apparently showed similar inverse associations, which makes reverse causation a less plausible alternative explanation. Another approach I wish authors had considered to address reverse causation is to verify the inverse association with dementia in a subgroup of participants with the least evidence of cognitive decline over the first 10 years of their luxurious 3-4 decades of follow-up.
“2. The second topic is a common complexity in nutritional epidemiology. Dietary exposures are inherently substitutional (when people don’t eat something, they usually eat something else as a substitution): Associations with coffee and tea consumption may reflect beverage substitution rather than the effect of coffee and tea in isolation, as non-consumers typically replace them with other beverages or habits. To address this, the authors controlled the associations for tertiles of non-caffeinated sugar-sweetened beverage intake and categories of alcohol intake. While it is a reasonable first step and necessary, I am not sure if statistical adjustment can fully address the issue. Stronger controlling approaches, such as testing these associations among abstainers, could have strengthened the evidence for a potential benefit of coffee and tea for brain ageing.”
Prof Jules Griffin, Director of the Rowett Institute, University of Aberdeen, said: “While this is an impressive study in terms of scale, the reduction in risk is quite a small decrease and so my message would be that if people wanted to reduce their risk of developing dementia there are other things they could consider that would have a bigger effect – not smoking, doing exercise, and reducing the intake of saturated fat and free sugar in our diets. As with any study based on associations there is also the question whether coffee or tea consumption is just part of a wider dietary or lifestyle pattern – for example, what are the non-coffee drinkers drinking and doing instead?”
Prof Eef Hogervorst, Professor of Biological Psychology, and Director of Dementia Research, National Centre for Sports and Exercise Medicine, Loughborough University, said:
“There is good biological plausibility for protective effects of caffeine on brain function. Caffeine is an adenosine antagonist and thus inhibits the inhibitor (adenosine) of many activating and memory improving neurotransmitter activity. These neurotransmitters activities are reduced by age, neuronal dysfunction and loss and dementia pathology affecting cognitive decline (e.g. dopamine) and dementia (e.g. acetylcholine) symptoms. Caffeine acts on many other mechanisms associated with brain health and dementia, including reduction of inflammation and regulation of dysfunctional glucose metabolism. In people without dementia, lifetime consumption of >2 cups per day of caffeine was associated with lower levels of the toxic amyloid plaques
(https://www.nature.com/articles/s41398-019-0604-5.pdf) seen in Alzheimer’s disease (AD), the most common form of dementia. Lastly, coffee and tea have many other anti-oxidant components and vascular benefits. Unfortunately, green tea, which is thought to be very beneficial for health due to its multiple compounds, was not investigated separately. It was odd that in this study only 1-2 cups of tea were associated with optimal risk reduction, but this could relate to people in the US perhaps consuming less tea than coffee.
Dr. K S Parthasarathy
Dr. K S Parthasarathy is former Secretary, Atomic Energy Regulatory Board and a former Raja Ramanna Fellow in the Strategic Planning Group, Department of Atomic Energy, Mumbai. Dr. K S Parthasarathy may be contacted at ksparth@yahoo.co.uk
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