25 April 2008

Does getting old have to mean worsening memory, slower reactions and fuzzy thinking?

AROUND the age of 40, honest folks may already admit to noticing changes in their mental abilities. This is the beginning of a gradual decline that in all too many of us will culminate in full-blown dementia. If it were possible somehow to reverse it, slow it or mask it, wouldn't you?



A few drugs that might do the job, known as "cognitive enhancement", are already on the market, and a few dozen others are on the way. Perhaps the best-known is modafinil. Licensed to treat narcolepsy, the condition that causes people to suddenly fall asleep, it has notable effects in healthy people too. Modafinil can keep a person awake and alert for 90 hours straight, with none of the jitteriness and bad concentration that amphetamines or even coffee seem to produce.



In fact, with the help of modafinil, sleep-deprived people can perform even better than their well-rested, unmedicated selves. The forfeited rest doesn't even need to be made good. Military research is finding that people can stay awake for 40 hours, sleep the normal 8 hours, and then pull a few more all-nighters with no ill effects. It's an open secret that many, perhaps most, prescriptions for modafinil are written not for people who suffer from narcolepsy, but for those who simply want to stay awake. Similarly, many people are using Ritalin not because they suffer from attention deficit or any other disorder, but because they want superior concentration during exams or heavy-duty negotiations.



The pharmaceutical pipeline is clogged with promising compounds - drugs that act on the nicotinic receptors that smokers have long exploited, drugs that work on the cannabinoid system to block pot-smoking-type effects. Some drugs have also been specially designed to augment memory. Many of these look genuinely plausible: they seem to work, and without any major side effects.



So why aren't we all on cognitive enhancers already? "We need to be careful what we wish for," says Daniele Piomelli at the University of California at Irvine. He is studying the body's cannabinoid system with a view to making memories less emotionally charged in people suffering from post-traumatic stress disorder. Tinkering with memory may have unwanted effects, he warns. "Ultimately we may end up remembering things we don't want to."



Gary Lynch, also at UC Irvine, voices a similar concern. He is the inventor of ampakines, a class of drugs that changes the rules about how a memory is encoded and how strong a memory trace is - the essence of learning (see New Scientist, 14 May, p 6). But maybe the rules have already been optimised by evolution, he suggests. What looks to be an improvement could have hidden downsides.



Still, the opportunity may be too tempting to pass up. The drug acts only in the brain, claims Lynch. It has a short half-life of hours. Ampakines have been shown to restore function to severely sleep-deprived monkeys that would otherwise perform poorly. Preliminary studies in humans are just as exciting. You could make an elderly person perform like a much younger person, he says. And who doesn't wish for that?


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