Studies have shown that there are much higher instances of mental disorder in political leaders and creative geniuses than in the general population. And while it's impossible to be completely sure of a correct diagnosis of a historical figure, that hasn't stopped researchers from making educated guesses. Here's a speculative look at the mental health of 11 of history's big thinkers.

1. ABRAHAM LINCOLN // DEPRESSION

The Great Emancipator managed to lead the country through one of its more trying times, despite suffering from severe depression most of his life. According to one Lincoln biographer, letters left by the president's friends referred to him as "the most depressed person they've ever seen." On at least one occasion, he was so overcome with "melancholy" that he collapsed. Both his mother and numerous members of his father's family exhibited similar symptoms of severe depression, indicating he was probably biologically susceptible to the illness. Lincoln is even assumed to be the author of a poem published in 1838, "The Suicide's Soliloquy," which contains the lines:

Hell! What is hell to one like me

Who pleasures never knew;

By friends consigned to misery,

By hope deserted too?

2. LUDWIG VON BEETHOVEN // BIPOLAR DISORDER

When the composer died of liver failure in 1827, he had been self-medicating his many health problems with alcohol for decades. Sadly, much of what he may have suffered from probably could have been managed with today's medications, including a serious case of bipolar disorder. Beethoven's fits of mania were well known in his circle of friends, and when he was on a high he could compose numerous works at once. It was during his down periods that many of his most celebrated works were written. Sadly, that was also when he contemplated suicide, as he told his brothers in letters throughout his life. During the early part of 1813 he went through such a depressive period that he stopped caring about his appearance, and would fly into rages during dinner parties. He also stopped composing almost completely during that time.

3. EDVARD MUNCH // PANIC ATTACKS

The world's most famous panic attack occurred in Olso during January 1892. Munch recorded the episode in his diary:

"One evening I was walking along a path, the city was on one side and the fjord below. I felt tired and ill. I stopped and looked out over the fjord—the sun was setting, and the clouds turning blood red. I sensed a scream passing through nature."

This experience affected the artist so deeply he returned to the moment again and again, eventually making two paintings, two pastels, and a lithograph based on his experience, as well as penning a poem derived from the diary entry. While it isn't known if Munch had any more panic attacks, mental illness did run in his family; at the time of his episode, his bipolar sister was in an asylum.

4. MICHELANGELO // AUTISM

You might have wondered in the past just how someone could paint something as huge as the ceiling of the Sistine Chapel. According to a paper published in the Journal of Medical Biography in 2004, Michelangelo's single-minded routine may have been due to the disorder. According to descriptions by his contemporaries, the painter was "preoccupied with his own reality." Most of the male members of his family are recorded to have exhibited similar symptoms. Michelangelo also seems to have had difficulty forming relationships with people; he had few friends and didn't even attend his brother's funeral. All of this, combined with his obvious genius in math and art, led the researchers to believe that today Michelangelo would be considered high functioning on the autism spectrum.

5. CHARLES DICKENS // DEPRESSION

By his early 30s, Dickens was the most famous author in the world. He was wealthy and seemed to have it all. But after an unbelievably difficult childhood, which saw the author working in a boot factory and living on his own when his father was thrown in prison, Dickens would start falling into depressions with the start of each new novel. The first one to cause him problems was one of his lesser-known works, The Chimes, in 1844. After that, Dickens' friends wrote that he became down every time he set to work on a new project, but that his mood would gradually lift until he was in a kind of mania by the time he finished. His depression worsened with age, and he eventually separated from his wife—the mother of his 10 children—to live with an 18-year-old actress. After he was involved in a train crash four years before his death, in which he was uninjured but was forced to assist dying passengers before help came, his depression seems to have finally staunched his creativity, and his previously prolific output virtually ceased.

6. CHARLES DARWIN // AGORAPHOBIA

Scholars still debate just exactly what problems Darwin suffered from, but whatever they were, they were serious. Despite his famed five year voyage on the Beagle (and the publication it led to) making his career, Darwin was virtually incapacitated the entire time. While he concentrated on his physical symptoms as the cause of all his suffering, the constant trembling, nausea, hysterical crying, and visual hallucinations (among other things) seem to have been mostly caused by a severe case of agoraphobia that kept him virtually bedridden from the time he turned 30. Darwin's fear of people meant he would even avoid conversations with his own children, writing, "I am forced to live… very quietly and am able to see scarcely anybody and cannot even talk long with my nearest relations." In at least one letter he mentions feeling like committing suicide due to the publication of On the Origin of Species, the controversy over which caused him much distress. He may have also suffered from OCD and hypochondria, as he kept meticulous records of every new or recurring symptom.

7. WINSTON CHURCHILL // BIPOLAR DISORDER

Like Lincoln, Churchill was a great leader dealing not only with international strife but his own mental struggles at the same time. In his 30s, he complained to his friends that he was hounded by the "black dog of depression." He sat in the Houses of Parliament and contemplated suicide. Churchill told his doctor that he had to be careful where he stood in a train station:

"I don't like standing near the edge of a platform when an express train is passing through," he told his doctor. "I like to stand right back and if possible get a pillar between me and the train. I don't like to stand by the side of a ship and look down into the water. A second's action would end everything. A few drops of desperation."

The black dog would follow him the rest of his life. When in his mild manic phases he was personable, but his moods could change quickly. During periods of high mania he would stay up all night writing, eventually producing 43 books on top of attending to his political duties.

8. VASLAV NIJINSKY // SCHIZOPHRENIA

While not well-known today, in the early 1900s, Nijinsky was a household name. Considered the greatest male dancer of his era, he was famous for his intense performances, gigantic leaps, and ability to dance on his toes (en pointe), something uncommon among male dancers at the time. When he took to choreographing ballets, his modern take on the dance led to a riot. By the time Nijinsky was 26, the symptoms of his disease were affecting his work. He spent the rest of his life in and out of mental hospitals, often going weeks at a time without saying a word.

9. KURT GÖDEL // PERSECUTORY DELUSIONS

Gödel was a brilliant logician and mathematician, as well as a contemporary and great friend of Albert Einstein. Einstein's super-intelligence might have made him seem a little odd to the average person, but he doesn't seem to have suffered from any actual mental illnesses. Gödel, on the other hand, thought that someone was out to poison him. He was so sure of this delusion, especially later in life, that he would only eat food that his wife had cooked, and usually made her taste it first, just to be sure. When his wife was hospitalized for six months, Gödel stopped eating and starved to death.

10. LEO TOLSTOY // DEPRESSION

Tolstoy did not suffer from obvious signs of depression until middle age, but when it hit him, it hit hard. He went through serious personality changes, questioning virtually everything in his life. At times he debated giving away all of his possessions, becoming celibate, and the nature of his religious beliefs (or lack thereof). At one point he was determined to give up writing altogether, saying, "art is not only useless but even harmful." Tolstoy is a perfect example of someone who seemingly has everything brought low by this disease: despite coming from a wealthy family, being celebrated as an author, and being father to 13 children, eventually his demons drove him to seriously consider suicide. He wrote in one letter, "The possibility of killing himself has been given to man, and therefore he may kill himself." Eventually Tolstoy pulled himself out of this hole by becoming what we would now consider a born-again Christian.

11. ISSAC NEWTON // BIPOLAR, AUTISM, SCHIZOPHRENIA

One of the greatest scientists of all time is also the hardest genius to diagnose, but historians agree he had a lot going on. Newton suffered from huge ups and downs in his moods, indicating bipolar disorder, combined with psychotic tendencies. His inability to connect with people could place him on the autism spectrum. He also had a tendency to write letters filled with mad delusions, which some medical historians feel strongly indicates schizophrenia. Whether he suffered from one or a combination of these serious illnesses, they did not stop him from inventing calculus, explaining gravity, and building telescopes, among his other great scientific achievements.