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The Scientist, Redheads and pain, November 11, 2002

November 11, 2002 By Hal Cohen

Redheads often turn the heads of passers-by with their distinctive hair color, and now they’re drawing particular notice from anesthesiologists. A study released last month at the annual meeting of the American Society of Anesthesiologists linked red hair to an increased need for anesthetics. Edward Liem, University of Louisville, Ky., says the study was conducted based upon anecdotal, clinical observations from several anesthesiologists. It is the first example of a phenotype associated with anesthetic dosage. “We’ve seen differences due to age, but no one before has shown any difference between hair color,” he says. Redheads have a dysfunction in the melanocortin 1 receptor that is responsible fir their freckles and their hair color. Liem hypothesizes that the defect causes an increase in α-melanocyte stimulating hormone and is responsible for lowering the pain perception threshold. The study indicates that redheads need about 20% more anesthesia than brunettes and blondes. Other physiological observations, such as the tendency toward bleeding and hypertension while under anesthesia, have previously been observed in redheads. But, Liem says, it’s questionable whether those are due to receptor dysfunction.