The Independent struggles to find some.

And as one enthusiastic US student user of Adderall put it, it only helps as a cognitive enhancer if you are dedicated to completing the essay you have set out to write: “The number of times I’ve taken Adderall late at night and decided that, rather than starting my paper, hey, I’ll organise my entire music library! I’ve seen people obsessively cleaning their rooms on it.”

The essays he wrote on Adderall also tended to be long-winded, with two pages given to creating an “airtight argument” where a couple of sentences would have sufficed.

There’s the rub – the brain is a complex organ and a drug that improves performance in one aspect may hinder it in another. Drugs like Ritalin and Adderall work in part by raising the levels of dopamine in the brain. If you have enough, more may not help – indeed it may leave you over-stimulated and less able to concentrate.

The article is actually something of a bait-and-switch. You leave with a sense cog enhancement would be pretty great.