Brainpower: a rational guide to the myths

In the new Hollywood thriller, 'Limitless', Bradley Cooper plays a failing writer who uses a top-secret 'smart drug' to unlock his brain's potential. SYLVIA LEATHAMasks TCD neuroscientist Prof Shane O'Mara for a reality check on how the brain works

The film is based on the premise that we can only access 20 per cent of our brain. Is this true?

This is nonsense. There’s just no evidence that this is the case. In fact, the evidence is quite to the contrary. If you do a brain scan with someone in a resting state, you can see that the whole brain is actually profoundly active. The fact that you’re not aware of things the brain is doing doesn’t mean it’s not doing anything. It is constantly controlling a billion things, such as digestion, posture, an itch you might have, the amount of saliva in your mouth, and so on.

In Limitless, Cooper’s character gets access to a new drug that transforms his brain function so he’s able to remember everything, and he becomes a genius.

There are already some drugs out there that enhance brain function. Caffeine is one – it gives a transient boost to memory, principally by reducing the effects of fatigue. Nicotine can have similar short-term effects, as can other amphetamine-like drugs.

But while memory is important, forgetting stuff is also important. You don’t want to overcrowd your synapses, you don’t want your brain persistently bringing to life associations every time you do something. Besides, having total recall doesn’t make you a genius. If that were true, everyone who had Google would be a genius!

Can you clarify for readers everywhere whether alcohol truly does kill brain cells?

At low doses, alcohol doesn’t kill brain cells. However, at very high doses it clearly does, in the following way: alcohol has a depressant effect on the nervous system, it can cause the respiratory and other vital centres of the brain to shut down so you stop breathing properly. That restricts the oxygen supply to the brain, and brain cells will die as a result. If you drink yourself comatose regularly, that’s certainly not a good thing for your brain.

If brain cells do die, or get damaged, can they regenerate?

In most parts of the brain, cells can’t regenerate, but there are some small exceptions. For example, a particular part of the hippocampus has now been shown to actually continue to produce new brain cells all the way through life, though only in small numbers.

Can brain-training games make you smarter or improve your memory?

The evidence here is equivocal. One study shows that playing three-dimensional action games actually does improve spatial cognition. And there is some data suggesting that working memory can be improved a bit with particular brain-training regimes. But there aren’t enough large-scale, randomised control trials to suggest there is a profound general effect, and I wouldn’t be inclined to believe that there is.

Prof Shane O’Mara is director of experimental brain research at Trinity College Dublin’s Institute of Neuroscience, and is the curator of the Science Gallery’s Memory Lab exhibition, which continues until April 8th