Flowers for Algernon was made into the movie Charly, and Cliff Robertson won an Academy Award for the role in 1968, a long time ago when "mental retardation" described Charlie and his IQ of 68. Algernon is an average white lab mouse who is given an experimental drug that increases his intelligence threefold. Charlie is also given the drug but like Algernon, Charlie's intelligence is temporary.
In Morningside Heights by Joshua Henkin, Spence shows remarkable memory improvement after taking Arlo's experimental drug, but sadly his improvement is short-lived. If Henkin deliberately introduced this connection between the two stories I say "well-done' because by doing so he, in my opinion, not only shines a light on the right/wrong use of experimental drugs on patients but the focal point on Arlo with his painful low self-esteem caused by his learning difficulty, due to dyslexia, becomes more important to the story.