Abraham Lincoln is a deified figure in American history. His wife hasn’t been so lucky.

History has portrayed Mary Todd Lincoln as scandalous. Her spending habits, her long period of mourning for her three sons who died young and her husband who died next to her and her erratic behaviour later in life have all been examined in minute detail, a pattern of scrutiny that First Ladies continue to face today. For Lincoln, born on this day in 1818 as Mary Ann Todd, it has led many people to attempt to name a medical condition that might have explained her behavior.

Even in her own lifetime, Lincoln was considered eccentric, writes Ruth Graham for Slate. A decade after Lincoln’s death, she was tried for insanity by her only living son, Robert, and forcibly institutionalized in an asylum for months.

At that trial, documents Jean Harvey Baker in Mary Todd Lincoln: A Biography, the housekeeper of an hotel where Lincoln had stayed gave a testimony describing the former First Lady’s manner as “often nervous and excitable. She was not like ladies in general.”

Earlier in her life, Lincoln was portrayed as unhinged and volatile, writes Jeffrey Bloomer for Slate. She spent money—a lot of money—and had family ties to the Confederate South. After her husband’s death, the death of a third son six years later and her incarceration, she went overseas where she spent most of her remaining years.

“After her death in 1882, historians—all of them initially male—began to mine her legacy, advancing a questionable theory of lifelong mental illness that remains hotly debated today,” Bloomer writes.

Insane. Hypochondriacal. Menstrual. The “female wildcat of the age.” These are all terms, writes Jen Christensen for CNN, that historians employed to describe Lincoln. And they weren’t the only ones: later historians claimed that she “suffered from bipolar disorder, a diagnosis which, of course, did not exist in her lifetime,” Bloomer adds. Others advanced theories like Lyme disease, chronic fatigue and diabetes.

Earlier this year, John Sotos, a medical doctor who consulted on the television show House, M.D., offered a new angle. In a study published in Perspectives in Biology and Medicine, Sotos suggests that Lincoln may have had vitamin B12 deficiency caused by pernicious anemia. Although the only medical records from Lincoln’s life that still exist are from the four months when she was forcibly institutionalized, Sotos argues that ”about 100 historic sources, including 678 letters and photos from the time” are enough, Christensen writes.

As a young woman, Christensen writes, Lincoln was known as an intelligent and kind woman who was a great addition to parties. It was only after Lincoln became president that she gained a reputation for being bad-tempered and profligate. “In the White House fishbowl,” she writes, “the press constantly hounded her, and vicious gossips mocked her unflattering gowns, portraying her as a Confederate spy or a Western hick.” In that atmosphere, she lost both children and husband.

Whatever the possible cause of her behaviour, it’s hard to find any one reason for what happened to Lincoln, particularly at this remove. And some disagree with the practice of diagnosing historical figures at all.

Baker found another, less-medicalized way to describe Lincoln in the introduction to her book: “Like a flawed marble statue the cracks of which are repeatedly hammered, Mary Lincoln was a victim battered by personal adversity and trapped by destructive conventions of Victorian domesticity.”

She may have been the partner of one of America’s best-known presidents, but after all, she was only human.