She's been described as perhaps the most troubled first lady to set foot in the White House, with fearsome moods, depression, and paranoia. Now a doctor says he may have uncovered the secret to Mary Todd Lincoln's behavior: a vitamin deficiency. Interestingly, this latest theory in Perspectives in Biology and Medicine comes from cardiologist John G. Sotos, who helped come up with all those strange diseases decoded on the TV show House, per the New York Times. In what might as well be a plot from the show, Sotos was researching Abraham Lincoln—whom he suspects had a genetic syndrome that led to cancer—when he found an 1852 letter describing Mrs. Lincoln's sore mouth and set out to discover what ailed her. His theory? She suffered from pernicious anemia, an autoimmune disease "that impairs the body's ability to absorb food efficiently," says Sotos, per CBS News.
Sufferers become B12-deficient, and a lack of B12 can cause a wide range of health problems—including a sore tongue. It can wreak havoc on the entire body over time, reports the Washington Post. "You get a long list of symptoms," from headaches to irritability and hallucinations, Sotos says. "Mary had just about all of them." The first lady—who spent months in a mental hospital in later life—also had "a wide face, wide jaw, and widely separated blue eyes," as do many with pernicious anemia, he writes. What's more, her ancestors came from an area of Scotland where the disease was once prevalent. One doctor calls Sotos' study "ingenious," though there's no proof he's correct. But Sotos simply hopes historians cut Mrs. Lincoln some slack. "To have done as well as she did with the kind of handicaps that she had, I think that deserves admiration." (Someone stole Abraham Lincoln's hand.)