An MS Mystery - the Role of Childhood Suntan

Robert W. Griffith, MD

An interesting study of twins has been reported in the journal Neurology. Sun exposure levels were compared in 79 pairs of identical twins, where only one twin had multiple sclerosis (MS). The twin with the disease was found to have less sun exposure than the healthy twin. Of course, the investigator didn't focus on the sun exposure - it was just one question in a 60-page questionnaire exploring as many causative factors as possible. This just makes it all the more surprising.

Each twin was asked whether they or the other twin spent more time out of doors during hot weather, cold weather, spring, summer, winter, and fall. Also, which twin went sunbathing, going to the beach, and played team sports.

Each of the nine different sorts of sun exposure-related activities seemed to provide strong protection against MS. The known risk factors for MS are genetic (ruled out in this study), viral infections (e.g. infectious mononucleosis or mono), northern European descent (also ruled out for identical twins), and a cold climate. Maybe the sun exposure preventive factor is a corollary of the cold climate risk factor. Or perhaps sun exposure increases vitamin D, which in turn affects the immune status in a significant but not-yet-determined way.

Whatever the actual explanation, the finding represents an intriguing phenomenon that may well be an important clue as to the cause of MS. And when that is known, advances in treatment (and prevention) will follow.

Source
HealthandAge Blog

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