The story
- Researchers using the UK Biobank tracked 461,586 people aged 40 to 69 for a median of 13.4 years, watching for mood disorders (depression, bipolar) and stress disorders (PTSD, acute stress). None of the participants had been diagnosed with anything when the study began.
- The pattern that emerged was J-shaped. Two or three cups a day sat at the floor of the curve — the lowest associated risk. Drinking less didn't help; drinking more — five-plus cups — and the protection started to fade.
- The protective association held across instant, ground, and decaffeinated coffee — which complicates the obvious explanation. If decaf is helping too, it isn't simply the caffeine doing the work. Researchers don't yet know what is.
- The association between coffee consumption and mood disorders was stronger in men. The paper does not try to settle why.
- Studies like this don't prove coffee causes anything. They show what showed up next to what, across a very large group of people, over a long stretch of time. Moderate coffee drinkers tend to also do other things — sleep on a schedule, leave the house, sit with other humans in a kitchen — that can't be cleanly separated from the coffee.
- The findings were published in the Journal of Affective Disorders on April 15, 2026.
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Currently, there is growing interest in the role of diet and nutrition in the prevention and management of mental disorders.
— Study authors, Journal of Affective Disorders
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