The Aging Brain

I had an article this weekend in the Washington Post looking at the recent spate of "age defiance" - Dara Torres, Madonna, John McCain, etc. - and some recent neuroscience research:

A s a 27-year old science writer who still gets carded at bars, I often find discussions of the aging process pleasantly abstract. I'm more likely to use Clearasil than anti-wrinkle cream. But the spectacle of Torres's competing and McCain's campaigning has rekindled an important scientific debate about the inevitability of the aging process and what even young and middle-aged people can do to blunt the adverse effects of time.

New research demonstrates that Torres, Madonna and McCain's mother, Roberta -- who is still campaigning for her son at the age of 96 -- aren't rare outliers, but rather examples of a somewhat common phenomenon. According to scientists, it's entirely possible to grow significantly older without getting much slower -- as long as we're willing to put in the work. The elixir of youth, it turns out, is an old-fashioned cocktail: blood, sweat and tears.

This scientific research arrives just as the graying of the baby boomers is leading to an explosive growth in medical treatments that promise a perpetual adolescence. With its offerings of dietary supplements and caloric-restriction diets, face creams infused with fetal stem cells and injections of Botox, the anti-aging industry has managed to turn an inescapable biological process into a lucrative source of anxiety. What the latest science suggests, however, is that the best anti-aging treatment isn't something you apply to your skin or buy in a bottle: It's what you already have in your head. The bad news, of course, is that the same research shows that the passage of time is not an equal opportunity eroder.

Last year, a large study led by researchers at Harvard University compared the brains of young adults and senior citizens. As expected, the scientists found consistent differences between the two groups. The most significant occurred in a brain system known as the "default network," which is active when people turn their attention inward, as when they're trying to remember a name. The default network is defined by a series of pathways between the front of the brain -- this includes areas of the prefrontal cortex -- and the "back" of the brain, such as the cingulate cortex.

Under normal circumstances, the default network ensures that these two brain areas work in perfect sync. "When the front of the brain fires, you want to see the back of the brain fire right back," says Jessica Andrews-Hanna, the study's lead author. "Unfortunately, this connection seems to weaken with age, so that older people can end up with a rather disconnected brain." Andrews-Hanna suggests that deficits in the default network might be responsible for many of the classic symptoms of old age, such as an inability to focus and problems with memory retrieval.

So far, so depressing. The aging process is a biological wrecking crew. But buried in all the bad news are some optimistic data. It turned out that nearly half of the older subjects exhibited brain activity that appeared indistinguishable from that of the young adults: Their default system was nearly as synchronized as those of people in their 20s. Furthermore, these differences in brain activity were correlated with performance on a battery of tests that measured short-term memory, abstract reasoning powers and processing speed. "There really was tremendous individual variation," Andrews-Hanna says, "and this variation was evident both in the brain and in observed behavior."

For more on the inequality of aging, check out Ed Yong's excellent summary of some interesting research on extreme lifespans.