Was Abraham Lincoln mad as a hatter? Perhaps, says retired physician and medical sleuth Norbert Hirschhorn. A decade before Lincoln became president, he may have suffered from mercury poisoning, the same malady that caused the shakes among felt-curing Victorian hatters.
Hirschhorn uncovered historical accounts that Lincoln had tried to combat melancholia by taking "blue mass," a commonplace medication made from mercury, licorice root, honey, sugar, and dried rose petals. His cure apparently had some untoward effects. During the 1850s, Lincoln suffered from insomnia, forgetfulness, hand tremors, and bizarre outbursts of rage— symptoms consistent with mercury poisoning. When Hirschhorn's colleagues reformulated blue mass from a 19th-century recipe, they found that a dose of just two pills contained 40 times as much mercury as the current safe limit set by the National Institute for Occupational Health.
Lincoln stopped taking the pills in 1861, five months into his presidency, after confiding to a former law partner that they "made him cross." It's a decision for which Americans should be grateful, Hirschhorn says. "If he had continued mercury while in the White House, could he have had the calm steadiness that was needed in such a stressful, terrible time? The answer, I think, is clearly no."