The attention deficit hyperactivity disorder (ADHD) drug Adderall does not improve reading comprehension or fluency in college students without the disorder, and may impair memory, a new study suggests.

Many college students believe ADHD drugs will improve their study skills, Science Daily reports. The new study by researchers at the University of Rhode Island and Brown University looked at the impact of so-called “study drugs” on college students who do not have ADHD.

The study, published in the journal Pharmacy, found the standard 30 milligram dose of Adderall did improve attention and focus, but did not translate into better performance on tests that measured short-term memory, reading comprehension and fluency.

“If your brain is functioning normally in those regions, the medication is unlikely to have a positive effect on cognition and my actually impair cognition. In other words, you need to have a deficit to benefit from the medicine,” lead researcher Lisa Weyandt said.