Few dietary exposures are as culturally embedded as coffee and tea. In an article published online yesterday in JAMA (February 9, 2026), Zhang et al reported findings from two huge US cohorts – female participants from the Nurses’ Health Study (n = 86 606; 1980-2023) and males from the Health Professionals Follow-up Study (n = 45 215; 1986-2023). (Zhang 2026)

The study examined associations between coffee and tea consumption and incident dementia, as well as trajectories of cognitive function over time. Their analyses suggest that moderate intake of coffee and tea is associated with a lower risk of dementia and more favourable cognitive ageing. This adds to a growing body of literature linking these widely consumed beverages to brain health.

The appeal of these findings is obvious. Dementia remains a leading cause of disability and dependency worldwide, and effective disease-modifying therapies remain limited. If a simple, low-cost, and culturally familiar habit such as coffee or tea consumption were shown to meaningfully reduce risk, the public health implications would be substantial. As always in nutritional science, however, careful interpretation is essential.

Strengths of the Evidence

This study is notable for its large sample size, long duration of follow-up, and use of repeated cognitive assessments rather than reliance on a single cross-sectional measure. The authors adjusted for a wide range of sociodemographic, lifestyle, and health-related confounders, and explored non-linear dose–response relationships, identifying apparent thresholds beyond which benefit plateaued or diminished. The internal consistency of associations across both dementia incidence and cognitive decline lends coherence to the findings.

Biological plausibility also supports these observations. Coffee and tea contain caffeine alongside polyphenols and other bioactive compounds that may influence neuroinflammation, oxidative stress, insulin sensitivity, and cerebrovascular function—mechanisms increasingly implicated in cognitive aging and dementia pathogenesis. (Socala 2020)

Persistent Methodological Challenges

Despite these strengths, the study remains observational, and its conclusions must be interpreted within that limitation. Residual confounding remains a central concern. Coffee and tea consumption are strongly patterned by education, socioeconomic status, social engagement, and other health-promoting behaviors—factors independently associated with lower dementia risk and difficult to fully disentangle statistically.

Reverse causation also warrants consideration. Subtle cognitive changes may precede clinical dementia diagnoses by many years and could influence dietary habits well before disease recognition. While sensitivity analyses reduce this concern, they cannot eliminate it entirely.

Measurement limitations further complicate interpretation. Self-reported beverage intake may not capture long-term patterns, preparation methods, cup size, or additives such as sugar and cream, all of which may meaningfully alter metabolic and vascular effects. Moreover, effect sizes, though statistically significant, are modest—important at the population level but easily overstated at the individual level.

Implications for Practice and Research

From a clinical perspective, these findings do not justify prescribing coffee or tea as a dementia prevention strategy as this was not RCT level evidence. They do, however, offer reassurance (for me personally) that moderate consumption appears safe, and may even be beneficial, within the context of an overall healthy lifestyle. For individuals who already enjoy coffee or tea, these beverages could possibly be framed as compatible with brain-healthy behaviors rather than as exposures to avoid.

For researchers, the study highlights both the promise and the limitations of large observational cohorts. Future work integrating biomarkers, genetic risk stratification, and more granular exposure assessment may help clarify causality and identify subgroups most likely to benefit. Ultimately, randomized trials—though challenging in this domain—will be required to move from association to actionable prevention.

Reflecting on our morning rituals

What this study invites, beyond epidemiology, is a quieter reflection on how everyday rituals can shape health across decades. Coffee and tea are rarely consumed as isolated compounds. They arrive with plant polyphenols, with preparation traditions, with pauses in the day, and often with conversation or contemplation.

The potential signal observed here may lie not in caffeine, polyphenols or bioactive ingredients alone, but in the broader matrix of self-care rituals and in the rhythms of life that often accompany these drinks. This may also explain why such findings do not translate neatly to other caffeinated beverages stripped of their botanical context or burdened with added sugars.

For those of us who cook, share meals, and return to familiar foods for comfort and grounding, the lesson is not that coffee or tea are protective in any deterministic sense. Rather, it is that health often accumulates through small, repeated choices embedded in daily life—through foods and habits that nourish not just the body, but attention, connection, and continuity over time.

P.S. If you’d like to read the full-text PDF of the JAMA paper by Zhang et al., feel free to reach out. Please note that this is shared for personal, educational use only, in keeping with academic access guidelines.

P.P.S. A special thank you to Dr Janice Bell for bringing this paper to my attention.

References

Zhang Y, Liu Y, Li Y, et al. Coffee and Tea Intake, Dementia Risk, and Cognitive Function. JAMA. Published online February 9, 2026. doi:10.1001/jama.2025.27259

Socała K, Szopa A, Serefko A, Poleszak E, Wlaź P. Neuroprotective Effects of Coffee Bioactive Compounds: A Review. Int J Mol Sci. 2020;22(1):107. Published 2020 Dec 24. doi:10.3390/ijms22010107