Large doses of caffeine are known to constrict blood vessels supplying the brain. Now researchers have found that going without the brew for about a day and half increases blood flow to the brains of heavy coffee drinkers 30% more than it does in light coffee drinkers.
"It's way above what a person normally experiences," study coauthor Dr. Paul J. Laurienti says of the increased blood flow.
The surge may explain the headaches that plague people when they first give up coffee. But what concerns Laurienti and Jonathan H. Burdette, assistant professors of radiology at Wake Forest University Baptist Medical Center in Winston-Salem, N.C., is that it may make perfusion MRIs, which allow physicians to identify differences in blood flow, hard to read.