20/04/2026
Koffie irt dementie en Alzheimer
Observational cohort studies have consistently linked moderate coffee drinking to lower dementia risk. The relationship is not linear. It follows a U-shape, and the shape matters as much as the direction.
The most recent comprehensive meta-analysis, Mazzoleni and colleagues (2026, J Epidemiol Popul Health) pooled 10 cohort studies with more than 450,000 participants and a mean follow-up of 11.5 years. The lowest risk of all-cause dementia sat at 2 to 3 cups per day, roughly 300 to 450 mL. Above 3 cups, Alzheimer's-specific risk started to rise.
A larger 2024 meta-analysis by Li and colleagues (Food Funct) looked at 38 cohorts totaling 751,824 participants with 13,017 dementia cases. The pooled highest-versus-lowest comparison for coffee showed only a weak signal (RR 0.95, 95% CI 0.87-1.02). When they modeled the dose-response properly with restricted cubic splines, the non-linear protective effect appeared in the 1 to 3 cups per day range. The shape is the finding.
The strongest single-study signal comes from the CAIDE cohort. Eskelinen and colleagues (2009, J Alzheimers Dis) followed 1,409 Finnish adults for 21 years. Those who drank 3 to 5 cups per day at midlife had 65% lower odds of developing dementia or Alzheimer's by ages 65 to 79, adjusted for demographics, lifestyle, vascular risk factors, APOE ε4 status, and depressive symptoms. Midlife exposure appeared to matter more than late-life intake.
UK Biobank data extends this into cognitive decline specifically. Rainey-Smith and colleagues (2025, J Alzheimers Dis) tracked 8,715 older adults over a mean 9.1 years. Moderate coffee drinkers (1 to 3 cups/day) showed slower fluid intelligence decline and fewer pairs-matching errors than high consumers (4+ cups/day).
A few caveats that matter.
This is observational data. Coffee drinkers differ from non-drinkers in many ways the statistical models can only partially adjust for. No randomized trial has ever assigned adults to drink coffee for 20 years and tracked dementia outcomes. The direction of the association is consistent across cohorts and continents, but correlation at this scale still leaves room for residual confounding.
The mechanism is plausible but unconfirmed in humans at endpoint. Caffeine antagonizes adenosine A2A receptors implicated in amyloid and tau pathology in preclinical models. Chlorogenic acids, trigonelline, and other polyphenols carry antioxidant and anti-inflammatory activity. These are reasonable hypotheses. They do not prove causation.
All-cause dementia and Alzheimer's disease respond differently. The U-shape is cleanest for all-cause dementia. For Alzheimer's specifically, Mazzoleni 2026 found the curve flat up to 3 cups, then rising. The protective signal is strongest for vascular and mixed dementia subtypes, not pure AD.
What the data actually supports: moderate, habitual coffee drinking (1 to 3 cups per day) is associated with lower dementia risk across hundreds of thousands of participants and decades of follow-up. More coffee is not more protective. For people already drinking 2 to 3 cups, the evidence base does not argue for changing anything. For people drinking 5 to 6 cups, the benefit curve has flattened and the Alzheimer's-specific curve has turned upward.
Sources:
Mazzoleni et al., J Epidemiol Popul Health, 2026
Li et al., Food Funct, 2024
Eskelinen et al., J Alzheimers Dis, 2009
Rainey-Smith et al., J Alzheimers Dis, 2025
