A half-century ago, doctors from Europe and North America who spent time in central Africa were struck by the absence of multiple sclerosis there. Indeed, the farther from the equator people lived, the more prevalent multiple sclerosis (MS) seemed to become. Scandinavians faced a higher risk than most other people. Thus arose the “latitude hypothesis” of MS, suggesting that a lack of direct sunshine somehow contributed to the nerve-damaging immune malfunction underlying the disease.
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