Chances are you’ve seen the ads for Clearpill, which promises to unlock your potential and activate 100% of your brain - and then lists a huge number of side effects, which actually don’t seem that much worse than those on nicotine substitutes (seriously, read the small print on patches and gum). There’s even a website (www.clearpill.co.uk), where someone, who looks remarkably like Bradley Cooper, is extolling the virtues of NZT.

It’s quite convincing, given all the stuff pharmaceutical companies and advertisers are pushing at us every day and it is a real advertising campaign, just not for a wonder drug that will resolve the problem of school funding and university fees. It’s for a new movie, Limitless, starring – Bradley Cooper.

Naturally I wasn’t taken in by it, not because of my superior intelligence, but because I read the book (The Dark Fields) upon which the film is based a decade ago, and instantly recognised it.

One of the things that impressed me about the book was how the author managed to convey a sense of the effects of the drug, because reading it made you feel like you had taken the drug. OK, not to the actual extent being described, but a sense of its possibilities was there.

I did think at the time that it would make a great movie although I wasn’t sure how it could be translated to the screen as a lot of it is internalised and is recounted in the first person, while a lot of the “action” involved sitting in front of a computer.

For the most part the filmmakers have done a great job and actually added a lot of humour that wasn’t in the book, which is hardly surprising as the screenplay is by Leslie Dixon, whose credits include Overboard, Mrs Doubtfire, Freaky Friday (2003) and Hairspray.

The opening scenes of Cooper’s character Eddie Morra struggling with writer’s block were something I could more than relate to, which probably made them funnier than they really are.

On one of his writing aversion excursions Eddie happens to bump into his ex-brother-in-law Vernon, who takes pity on Eddie and his literary travails and gives him a sample pill of NZT to help him out.

Within minutes Eddie is a new man, and the writer’s block has gone. In a burst of creative energy he writes the book he has been struggling with for months and turns in a big chunk of it to his editor the following day. Unfortunately, the effects of the drug have worn off and he needs more to finish the job. He visits Vernon again to get some more pills, only to find the apartment ransacked and Vernon with a bullet in his head. Luckily for Eddie, he finds Vernon’s stash before the cops arrive.

After a couple of more doses Eddie starts seeing patterns in the stock market and begins making a lot of money very quickly, making him the toast of Wall Street. Now, remember the side-effects mentioned in the Clearpill ads? They start happening to Eddie and his supplies are getting low and he has a big merger he needs see through for mega-corporation boss Carl Van Loon (Robert De Niro). He’s also got Russian mobsters after him, and another very sinister character too. It’s not looking good for Eddie.

Naturally, it’s impossible to put everything from a book into a movie – unless it’s a Philip K Dick short story where they add more than was ever there – but this does capture a lot of the essence of the book and the story. Cooper is great in the lead and convincingly plays Eddie with both charm as a winner and angst and pathos as a loser.

There is a strong support cast with De Niro doing some of his better work in recent years as Van Loon. It’s not much of a stretch for him to play charming and menacing, but he does it without resorting to his familiar tics. Abbie Cornish does well as his girlfriend and Anna Friel is a surprise as Eddie’s ex-wife, and is about as far removed from her Pushing Daisies character as you could get without adding serious prosthetics.

Visually the film is a treat, and while is doesn’t have the same effect as the book, it certainly is interesting, with shades of Michel Gondry, as well as reminiscences of scenes from Fight Club and Stranger Than Fiction.

It is a good, solid entertaining movie, which offers a ray of hope in these difficult times. Unfortunately for me, having read the book, my only complaint was the ending, which was a total Hollywood cop out. My advice is, go and see the movie, enjoy it, because it is very enjoyable, then read the book. Just don’t read the book first.

LIMITLESS is in cinemas from March 23