A new study in JAMA yesterday gave us a smug feeling about our coffee habit. Researchers found that drinking two to three cups of caffeinated coffee daily has an association with an 18% lower risk of dementia and a 15% lower risk of subjective cognitive. But decaffeinated coffee had no such association.

This does not mean that coffee is good medicine for preventing dementia. An association with lower risk is not evidence for an effect. But is does give us a measure of permission for guilt-free enjoyment of this lovely beverage.

Oh, and let’s not leave the tea drinkers behind. Their habit had a similar association with less dementia risk.

Four Decades, 130,000 Persons

This new study set out to answer a simple but important question: do coffee and tea help protect our brains as we age? And does it matter whether the coffee has caffeine?

To find out, researchers followed more than 130,000 U.S. nurses and health professionals for up to four decades. Every two to four years, participants reported how much caffeinated coffee, decaffeinated coffee, and tea they drank. Over time, the researchers tracked who developed dementia, who reported worsening memory, and – among some women – how well they performed on standard cognitive tests.

The results were clear. People who drank caffeinated coffee or tea had a lower risk of developing dementia and were less likely to report memory problems. Those with the highest intake of caffeinated coffee had about an 18% lower risk of dementia than those who drank little or none. Tea showed a similar pattern. In contrast, decaffeinated coffee offered no such benefit.

The sweet spot appeared to be moderate use – about two to three cups of coffee or one to two cups of tea per day. More than that didn’t seem to add extra protection.

Is Caffeine the Factor?

In short, this long-term study suggests that caffeine, not coffee alone, has a link to better brain health and a lower risk of dementia.

Is it the cause of the better outcomes? Or is it merely a marker for them? This is a good study, but an association can only offer us clues. Not a definitive answer about cause and effect.

Click here for the study in JAMA, here and here for further perspective.

Lorette with Cup of Coffee, painting by Henri Matisse / WikiArt