Here are "31 Strange Medical Conditions," courtesy of John Green (who is awesome) and the Mental Floss team (also awesome). Charlie doesn't get a mention, nor do his films, but observe this:
#19 - Walking Corpse Syndrome, a.k.a. Cotard's Delusion. Synecdoche, New York's lead character, I probably don't need to point out again, is named Caden Cotard.
#20 - Capgras Delusion. At one point in Synecdoche, when Caden visits Adele’s flat, "Capgras" is one of the names on the building's address list.
#21 - Fregoli Delusion. You know Anomalisa? Charlie's upcoming animated film, based on his own play? When he wrote the play, he originally hid under the pseudonym "Francis Fregoli". (The Coen Bros' half of Theater of the New Year couldn't be performed in L.A., due to scheduling conflicts, so Charlie wrote a second play -- "Anomalisa" -- to double bill with his "Hope Leaves the Theater.")
John Green has a weekly show on the Mental Floss channel. It is cool. I recommend it. I'll embed another episode after the cut. Just for fun. Cos I'm cool, too.