terça-feira, 11 de janeiro de 2011

Can You Build a Better Brain?

December 2010

Blueberries and crossword puzzles aren’t going to do it. But as neuroscientists discover the mechanisms of intelligence, they are identifying what really works

Illustration by Peter Arkle for Newsweek
This would be a whole lot easier—this quest for ways to improve our brain—if scientists understood the mechanisms of intelligence even half as well as they do the mechanisms of, say, muscular strength. If we had the neuronal version of how lifting weights increases strength (chemical and electrical signals increase the number of filament bundles inside muscle cells), we’d be good to go. For starters, we could dismiss claims for the brain versions of eight-second abs—claims that if we use this brain-training website or practice that form of meditation or eat blueberries or chew gum or have lots of friends, we will be smarter and more creative, able to figure out whether to do a Roth conversion, remember who gave us that fruitcake (the better to retaliate next year), and actually understand the NFL’s wild-card tiebreaker system.

But what neuroscientists don’t know about the mechanisms of cognition—about what is physically different between a dumb brain and a smart one and how to make the first more like the second—could fill volumes. Actually, it does. Whether you go neuro-slumming (Googling “brain training”) or keep to the high road (searching PubMed, the database of biomedical journals, for “cognitive enhancement”), you will find no dearth of advice. But it is rife with problems. Many of the suggestions come from observational studies, which take people who do X and ask, are they smarter (by some measure) than people who do not do X? 

Just because the answer is yes doesn’t mean X makes you smart. People who use their gym locker tend to be fitter than those who don’t, but it is not using a gym locker that raises your aerobic capacity. Knowing the mechanisms of exercise physiology averts that error. Not knowing the mechanism of cognitive enhancement makes us sitting ducks for dubious claims, since few studies claiming that X makes people smarter invoke any plausible mechanism by which that might happen. “There are lots of quick and dirty studies of cognitive enhancement that make the news, but the number of rigorous, well-designed studies that will stand the test of time is much smaller,” says neuroscientist Peter Snyder of Brown University Medical School. “We’re sort of in the Wild West.”

A 2010 evaluation of purported ways to maintain or improve cognitive function, conducted for the National Institutes of Health, shows how many of the claims for cognitive enhancers are as sketchy as a Wild West poker player with a fifth ace up his sleeve. Vitamins B6, B12, and E; beta carotene; folic acid; and the trendy antioxidants called flavenoids are all busts, and the evidence for alcohol, omega-3s (the fatty acids in fish), or having a large social network is weak. The Mediterranean diet is associated with a lower risk of cognitive decline, find observational studies, but that hasn’t been confirmed in more rigorous, randomized controlled studies, and no one knows whether the benefit comes from what the diet includes (olive oil, fish, vegetables, wine) or what it excludes (red meat, refined sugars, dairy fat). 

Statins don’t help, and neither do estrogen or NSAIDs (aspirin, ibuprofen). Be skeptical of practices that promise to make you smarter by increasing blood flow to the brain—there is no evidence that’s the limiting factor in normal people. Yes, you can find individual studies concluding that one or another hype-heavy intervention helps your brain, but the conclusion of any single study is more likely to be wrong than right. (For one thing, scientists and journals prefer positive findings and bury negative studies.) Only by assessing all the evidence from all the studies, as the NIH evaluation did, can you get the true picture.

Source: http://www.newsweek.com

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