Maintaining the Brain-Attic: Sherlock Holmes’s Mental Health

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To celebrate the birthday of Arthur Conan Doyle, we’re writing about all things Sherlockian/ACD today. This piece on Sherlock Holmes’s mental health is sponsored by The 7 ½ Deaths of Evelyn Hardcastle by Stuart Turton.

The most inventive debut of 2018, this clever, mind-bending murder mystery will leave readers guessing until the very last page.

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At a gala party thrown by her parents, Evelyn Hardcastle will be killed. Again. She’s been murdered hundreds of times, and each day, Aiden Bishop is too late to save her. Doomed to repeat the same day over and over, Aiden’s only escape is to solve Evelyn Hardcastle’s murder. However nothing and no one are quite what they seem.

The sixth season of Elementary, CBS’s modern-day take on the legendary duo of Holmes and Watson, recently debuted with the revelation that Sherlock Holmes’s mental health has taken a hit.  He is suffering from post-concussion syndrome, a condition that will interfere with his ability to do his job and even to be himself. It’s shaping up to be the season’s big story arc, so now seems like a good time to discuss just what goes on in Holmes’s head anyway.

Jonny Lee Miller as Sherlock Holmes in Elementary Sherlock Holmes mental health

Sherlock Holmes has one of the most revered minds in all of fiction. He’s been rightfully celebrated for his powers of observation, his inductive skills, and his cool logic. And yet we still know so little about how his brain actually works. Because Arthur Conan Doyle wrote these stories well before many neurological conditions were named or properly understood, and because Arthur Conan Doyle didn’t give two figs for continuity, the idea of playing armchair psychologist and making a definite diagnosis is laughable. Instead, like with all other parts of the canon, everything we read is a matter of individual interpretation. So let’s look at some of the possible interpretations, shall we?

Substance Abuse

Whether or not Holmes’s drug use ever veered into outright addiction is a popular topic for adaptations to delve into. Watson expressed alarm about Holmes’s drug habit more than once in the canon. “I was horrified by my first glimpse of Holmes next morning…” Watson reports in The Missing Three-Quarter, when he finds Holmes with a syringe. “I feared the worst when I saw it glittering in his hand.”

Don’t worry, though. In this case, Holmes was just using the syringe to spritz aniseed over a suspect’s carriage wheel to make for easier tracking. But that’s hardly enough to render Watson’s concerns invalid. Is it possible that Holmes could spend years intermittently using both morphine and cocaine and somehow not develop a dependency on either substance? Either way, addict or not, we can all agree that Holmes uses way too many drugs.  And that’s not even getting into his smoking habit…

Mental Illness

There is also the very real possibility that Holmes suffered from some kind of mental illness, something that caused him to “get in the dumps” and not speak “for days on end,” as Holmes describes it in A Study in Scarlet. That could signify a variety of things, including depression or perhaps bipolar disorder.

Insomnia may also be a symptom of whatever Holmes suffers from, though that depends on what story you read. In A Study in Scarlet, Watson claims Holmes regularly goes to bed by ten and is out of the house before Watson gets up in the mornings. But by The Hound of the Baskervilles, all of a sudden Holmes is a perpetually late riser, “save upon those not infrequent occasions when he was up all night.” Maybe he sometimes has trouble sleeping and sometimes doesn’t? Your guess is as good as ours.


Another popular theory posits that Holmes is on the autism spectrum.  While this would have made Holmes’s life more challenging in some respects, it could have proven advantageous in others. If Holmes is autistic, it would explain several facets of his personality in one fell swoop, including his:

  • lack of social graces. In The Norwood Builder, Holmes claps in delight at the prospect of his client going to jail. Said client is standing distraught right in front of him.
  • intense, focused interest in crime. Anything that isn’t crime-related, including sports trivia and heliocentrism, can go hang for all Holmes cares. But if something can serve him in his work, such as identifying different kinds of tobacco ash on sight, you can bet Holmes is the world’s foremost expert on the topic.
  • habit of forgetting to take care of himself. Again from The Norwood Builder, Watson says that, if the case is interesting enough, Holmes will starve himself until he passes out!

BBC’s Sherlock has played with the concept that their Holmes could be autistic, mainly via facetious comments from the other characters. Elementary also gave a nod in that direction. In season four, an autistic woman says that Watson is neuroatypical, but adds that she can’t quite tell if Holmes is neuroatypical or not.

And so we have come full circle.  Our discussion began with Elementary, and here it will end. All that remains is to remind our dear readers that the Holmes canon is inherently unreliable. This is as true regarding descriptions of Sherlock Holmes’s mental health as it is anything else. Holmes is clearly a complicated man, but how complicated, and in what ways?  There are no right or wrong answers here—just millions of devoted fans enjoying Holmes’s adventures in whatever way makes them happiest.