In recent years, some research has suggested that a high-fat
diet may be bad for the brain, at least in lab animals. Can
exercise protect against such damage? That question may have
particular relevance now, with the butter-and cream-laden
holidays fast approaching. And it has prompted several new and
important studies. The most captivating of these, presented last
month at the annual meeting of the Society for Neuroscience in
New Orleans, began with scientists at the University of
Minnesota teaching a group of rats to scamper from one chamber
to another when they heard a musical tone, an accepted measure
of the animals’ ability to learn and remember. For the next four
months, half of the rats ate normal chow. The others happily
consumed a much greasier diet, consisting of at least 40 percent
fat. Total calories were the same in both diets. After four
months, the animals repeated the memory test. Those on a normal
diet performed about the same as they had before; their
cognitive ability was the same. The high