Adderall, the "smart pills" that have become the drug of choice for those hoping for a brief brain boost, may not actually work. Scientists have a hard time finding evidence that Adderall and similar drugs, such as Ritalin, deliver any real benefit to those who take them, says Casey Schwartz in The Daily Beast, and a new study suggests that the effects the drugs are known for may be almost entirely within the subject's head. Here, a quick guide:

Who takes Adderall?
It's normally prescribed for people diagnosed with Attention Deficit Hyperactivity Disorder (ADHD), but is increasingly being used by college students and young professionals to enhance their mental performance.

Is there any proof that Adderall actually works?
There's plenty of anecdotal evidence. Slate's Joshua Foer found in 2005 that it gave him a "calming sensation, like a nicotine buzz, that lasts for several hours," allowing him to write quickly and concentrate more effectively. But, he condeded, he felt as if he were "thinking with blinders on." A regular Adderall user told Time last year that the pills give him "clarity of thinking and focus."

What does the science say?
Scientific attempts to prove these benefits have been mostly unsuccessful. "At best, the drugs show a small effect," says Schwartz. "More often, researchers come up with negative findings." In the most recent study, researchers gave 47 subjects tests on a "variety of cognitive functions," from memory tests to IQ problems. Each was tested while on Adderall and on a placebo, but were not told which was which. Students on Adderall were far more likely to say "the pill had caused them to do a better job on the tasks," even when their performance was not markedly better.

Why might students think they are doing better?
The drug "unleashes the feel-good neurotransmitter dopamine," says Schwartz, so it's "not suprising" that those who use it "believe they've done a fabulous job," no matter what the truth is.

Could that actually be good for students, though?
Perhaps, says Meredith Melnick at Time. It's possible that the mild euphoria brought on by Adderall "simply makes studying more pleasurable, helping student achievement by ramping up enthusiasm for academics overall." But it's far from obvious that "ecstasy" can strengthen "cognitive performance."

Sources: The Daily Beast, Time, Slate