Sherlock suffered from memory loss and hallucinations during the last few episodes of Elementary season 5, so what caused his mystery illness? Sherlock Holmes was created by Sir Arthur Conan Doyle and first appeared in the 1887 novel A Study In Scarlet. The adventures of Holmes and his friend Dr. Watson soon attracted a large fanbase. Doyle famously grew tired of his creation and killed him off - alongside his nemesis Moriarty - in the short story "The Final Problem." After years of fan demands, he resurrected Holmes for the classic novel The Hound Of The Baskervilles.
Holmes' popularity has rarely waned in the decades since his creation, with the character being featured in numerous film and TV adaptations. Robert Downey, Jr. and Jude Law starred as Holmes and Watson respectively in the Guy Ritchie Sherlock Holmes movies; both actors will return for the upcoming third entry. Benedict Cumberbatch (Doctor Strange) also became a star name thanks to his performance in the BBC's contemporary take on Sherlock, which debuted in 2010.
Another modern take on the character came in the form of CBS' Elementary, which stars Jonny Lee Miller (T2: Trainspotting) and Lucy Liu as Holmes and Watson. The show initially attracted minor controversy since it came so close after the BBC series, but the series has proved to be its own unique beast. The chemistry between the leads became its main selling point and the show is set to end with its upcoming seventh season.
Elementary season 5 found the legendary detective starting to experience painful headaches and memory loss during later episodes. He also befriends a mysterious woman at his support group, who later turns out to be a hallucination of his late mother May. This vision of his mother is really the part of Holmes that knows he needs help, though he keeps his condition a secret from Watson. Season 5 ends on a cliffhanger where Holmes undergoes an MRI scan to figure out what's happening with his brain.
Despite the Elementary season 5 finale ending on a major cliffhanger, fans had an anxious wait for CBS to renew the show for season 6. Mercifully, the series returned a year later and revealed Sherlock was suffering from post-concussion syndrome, which is the result of too many blows to the head. The sixth season finds Holmes really struggling to balance his condition with his work. It also requires him to take a prescribed set of medication, though his workaholic nature constantly puts his recovery - and sobriety - in jeopardy.
Elementary season 5 made it seem like Holmes might be suffering a tumor, but the post-concussion syndrome introduced in season 6 added a new dynamic to the show. Sherlock can no longer trust his own mind completely, meaning he has to work harder than usual. It also adds an intriguing wrinkle to his friendship with Watson.