Was Leonardo da Vinci Dyslexic?

Am J Med. 2019 Mar 7. doi: 10.1016/j.amjmed.2019.02.019
Salvatore Mangione, MD, Rolando Del Maestro, MD, PhD, FRCS(C), FACS, DABNS

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2019 marks the 500th anniversary of the death of Leonardo da Vinci, a man so talented in arts and science as to be arguably the most creative person who ever lived. His biographer, Giorgio Vasari, called him, “Largita da Dio” (a gift from God), and half a millennium later we still ponder what made him so unique. The recent observation that Leonardo might have suffered from intermittent exotropia sheds some light on his artistic genius, because ocular misalignment is often linked to talent in the visual arts, but also raises the possibility of dyslexia, because this too can result from misalignment.

Difficulty with the written word was first suggested by Sartori in 1987, based on Leonardo’s peculiar orthography, too bizarre and error-ridden to be caused by his mirror writing, Tuscan dialect, or the inconsistency of Renaissance Italian. Sartori proposed surface dysgraphia, a developmental disorder associated with dyslexia and characterized by incorrect spellings that create homophonic nonwords—such as writing rane for rain. Almost half of Leonardo’s misspellings (consonant doubling; blending/splitting of words; letter substitutions/additions/deletions) are, in fact, homophonic nonwords(Table).

Leonardo’s poor writing has traditionally been attributed to his limited schooling, in turn explained by his being illegitimate. Yet, other illegitimate children, such as Renaissance genius Leon Battista Alberti, were often well educated. Vasari writes that Leonardo would have made “great proficiency in the rudiment of letters” if only he had been less distracted by drawing, yet the real issue might have been dyslexia. Eventually, Leonardo’s poor school performance may have convinced his father to apprentice him to an artist rather than persisting with formal education. This was an unusual career choice for the first-born son of a wealthy Florentine notary, because artists were considered mere craftsmen at the lowest rung of society. Leonardo resented this connotation, and throughout his life never missed a chance to boast of the primacy of images over words, often blasting his academic critics as “fools” for accusing him of being a “omo sanza lettere” (an unlettered man). Later he tried to teach himself Latin, but in vain. He would even fill a notebook, The Codex Trivulzianus, with a plethora of Latin words in a futile attempt to learn the language.

Dyslexia may have channeled Leonardo’s focus into visual thinking, and thus provided the undercurrent of his creativity. It might also account for Leonardo’s brilliant intelligence and peculiar mirror writing. It may even explain why his notebooks were richer in pictures than words, a jumble of ideas that Leonardo intended to publish but never could. Ironically, they earned him scorn from academia, such as this barb by Baldassarre Castiglione: “One of the world’s foremost painters disdains the art where he truly excels and instead has set himself to study science. In that area, he has such strange and newfangled ideas that despite all his painting talents he can’t even depict them.”

Ultimately, dyslexia and its social/emotional repercussions may help us understand Leonardo’s feeling of being an outsider, including his famous comment: “Salvatico e’ quello che si salva” (only the loner saves himself.)