It’s ritual: You stumble into the kitchen at dawn, pour yourself a hot cup of coffee, and let the caffeine smooth your rough edges. It jump-starts your mental alertness, so it sounds paradoxical that coffee could also…shrink your brain?
Scientists at the University of Basel took stock of the gray matter in people’s brains after 10 days of daily caffeine consumption versus none, and found the caffeinated group had measurably less gray matter in the part of the brain that controls things like memory. “Daily caffeine consumption affects our cognitive hardware,” says study co-author Carlin Reichert.
While researchers are still trying to understand the direct effect of caffeine on brain neurons, one thing is clear: The loss of gray matter is not due to sleep disturbances from a java-wired brain. The people in the study slept the same with or without caffeine, indicating that it’s the drug itself that messes with your mind.
The good news: After 10 days of no caffeine, gray matter returned to higher levels.
While it’s not time to sell your espresso machine just yet, it may be wise to modify your coffee and cola habits: Study participants consumed 450 milligrams daily, so aim for less than half of that—200 mg or about two cups of coffee—to lessen the brain-shrinking effects.
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