Multiple sclerosis has skyrocketed in Tehran, increasing almost sevenfold between 1989 and 2005. In Iran’s central province of Isfahan, the incidence nearly tripled from 2005 to 2009. Now Oxford University researchers suggest, for the first time, that the 1979 Iranian Revolution may deserve some of the blame for the extraordinary jump. They say the revolutionary mandate for modest dress and head coverings for women may have inadvertently fueled the increase by limiting their exposure to sunlight.
Scientists have long recognized a link between lack of sunlight and multiple sclerosis (MS), a neurological disease that typically first strikes people in their 20s and 30s, and women more often than men. The disease, in which the immune system attacks the protective coverings on nerve fibers, is known to be more common among people at higher latitudes, possibly because of less vitamin D, which the body manufactures when skin is exposed to sunlight. Vitamin D deficiency might even come into play in the womb . Studies conducted in the United States and Europe, for example, show that babies born in April, whose mothers were pregnant during cold, dark months, have a higher risk of MS than babies born in October, whose mothers had spring and summer pregnancies.
The Oxford researchers—Julia Pakpoor and Sreeram Ramagopalan, who both study genetics —are careful to make clear that they aren’t telling women to abandon the hijab any more than they would tell New Englanders to move to Florida . Instead, the researchers encourage Iranians to supplement their diets with vitamin D pills. That advice goes for women and men in other cultures, too. Data show, for instance, that modestly dressed Orthodox Jewish mothers in Israel have lower vitamin D levels than women with more exposed skin.
The duo’s revolution-MS theory is consistent with studies published as recently as 2011 showing that Iranians do have low levels of vitamin D. But Pakpoor acknowledges that the theory is speculative. For one thing, MS rates are also going up in many other places, including parts of southern Italy, Norway, Kuwait and Japan. There’s no data showing exactly when MS rates started to rise in Iran, she says, and it’s unclear how much of the increase may be the result of better diagnoses. Still, the change is dramatic, with yearly diagnoses in Tehran rising from 0.68 per 100,000 people in 1989 to 4.58 per 100,000 in 2005. Though MS data are sparse for much of the world, Iran’s rates now appear comparable to those in some European countries.
“In order to explain such a rapid rise, you’re looking for something that is specific to Iran,” Pakpoor says.
But Iranian researcher Amir-Hadi Maghzi is cautious . Maghzi, who at age 26 has published more than 40 studies on MS and is now a postdoctoral fellow at the University of California San Francisco, believes that clothing may be just one of many factors acting in combination with a genetic predisposition among Iranians. Increased sunscreen use, as well as a move toward apartment living and better hygiene, might also contribute, he says.
Maghzi agrees that Iranians should take vitamin D supplements. He does. After getting his own blood tested, he discovered that despite moving to California for his fellowship, he doesn’t have enough D.