Younger by Hunger

The most effective ways of shielding your brain from the ravages oftime--soaking it in formaldehyde, freezing at arctic temperatures--are best reserved for those who have already met their maker. For the living, there may be a more feasible alternative: Eat less.

Researchers at Penn State University were able to ward off brain deterioration in rats--when they cut the rodents's lifetime caloric intake by 50 percent. (In human terms, that's roughly equal to skipping dinner and dessert for 70 years.) Maybe formaldehyde isn't so bad after all.

In the study, Jonathan R. Day, Ph.D., of Penn's Institute of Gerontology, and Daniel Major, now at the University of California, looked at levels of a brain protein called GFAP.

Produced by astrocytes--special cells whose duties include protecting brain neurons from toxins--GFAP forms part of the cytoskeleton, the cells's internal support structure. GFAP levels normally rise with age, brain injury, and neurodegenerative disease. "We don't know why astrocytes feel compelled to make this extra GFAP," says Day, but indications are it's a sign of neuronal damage.

When Day and Major put rats on a low-cal diet, GFAP levels fell in the hippocampus, a part of the brain vital for learning and memory. Their interpretation: Eating "lite" may retard the aging process in the brain.

Surprisingly, a healthy hippocampus didn't help the rats learn any better. Performance on a maze test actually declined compared to well-fed controls. Day offers an explanation that relies less on biochemistry than everyday experience: It's hard to concentrate when you're hungry.

While the study confirmed the long-standing observation that eating less may increase life span--at least if you're a rat--it leaves a crucial question unanswered: What good's a healthy brain if you can't enjoy milk shakes and cheesecake?