In Lost Stars, Cienna and Thane were constantly competing academically and never mentioned trying to use drugs to do better in school. Does that mean nootropics don't exist in the Star Wars galaxy?
None appear in canon, but multiple drugs that could be described as nootropics appear in Legends.
Mnemiotic drugs were given to all Imperial Intelligence trainees, soldiers, and assassins to boost their memory retention rate. Overuse of the drug could cause hallucinations and brain damage.
The Memory package was an implant that stimulated the brain, effectively increasing the user's intelligent thought. It reinforced and augmented the synapses in the memory centers of the brain, making it possible to recall knowledge locked away in the user's mind. This was said to have been cheaper than a trip to the libraries at Coruscant.
A neural stimulant was a chemical. Quarlo I'Shibix laced eldratz spice with a neural stimulant to encourage higher productivity amongst his Kluuzot workers.
Adrenals were drugs used to heighten reflexes and aid in concentration. The chemicals to make these stimulants could be found on the planet of Quesh.
Haladreshin was a chemical compound that acted as a neurological stimulant. It cost two hundred credits per dose and the effects lasted for approximately eight standard hours,
They're apparently alarmingly easy to access. I guess there is no "Star War on Drugs."
First, to point out a flaw in your reasoning: Just because I've never mentioned something doesn't mean it doesn't exist.
According to Google, the definition of nootropics is:
(of a drug) used to enhance memory or other cognitive functions.
Nootropics do exist in Star Wars. We call them spice:
Spice, also known as narco-spice was slang for various mind-altering drugs. Varieties included ryll and the strongest (and most expensive), glitterstim.
Glitterstim in particular is worthy of note:
Glitterstim was the name of a potent variety of the drug family "spice" that was mined on Kessel. It gave the user a brief, yet pleasurable telepathic boost and heightened mental state.
Glitterstim was once used by a Kessel spice miner using illegal slave labour to search Hani Solo's mind for evidence that he was sent as a New Republic spy.
Technically, if you can afford glitterstim then you'll never fail your exams even if you've never studied all your life as long as someone in class did. The poor kids do all the work and the rich kids reap all the rewards. You can enjoy your exams while at it too!