A new paper published in Nature finds another factor that falls somewhere in between those extremes. It suggests that excessive neural activity in the brain is linked to a shorter lifespan, and that suppressing that extra activity could prolong it. The finding is preliminary, and will require far more research before it results in any concrete health recommendations—but it opens up the possibility of using either drugs or behavioral interventions, such as meditation, to alter the brain’s activity, and possibly slow the effects of aging.
The link between nervous system activity and longevity wasn’t totally unexpected. The mechanism that controls brain excitation is closely related to the one that controls metabolism, which has long been linked to lifespan, says study co-author Dr. Bruce Yankner, a professor of genetics and neurology at Harvard Medical School.
But the fact that less brain activity was associated with longevity at first seemed “counterintuitive” to Yankner, who assumed an active brain would be linked with better health and vitality. After he and his colleagues examined the brain tissue of hundreds of deceased human subjects, grouped by their age of death, they found that the tissue of those who lived longer lives, dying at 90 or 100, suggested they had experienced less neural activity than those who died in their 70s or 80s.
“One potential explanation was that this could have been a correlation: as people get older, their brains slow down,” Yankner says. Those who died younger, they thought, may simply have died of causes unrelated to neural activity. But without being able to test that theory in humans, they turned to worms, which are often used in aging research due to their short, easy-to-study lifespans.
What they found was beyond coincidence. Using brain imaging, they saw that worms’ neural activity increased with age—and when the researchers gave the worms a drug that would calm some of that activity, they lived longer. When the researchers stimulated the worms’ neurons, they died faster. “It wasn’t due to some confounding factor,” Yankner says. “It seemed to be a primary effect.” Tests in mice showed similar effects.
Next, the researchers tried to find the “CEO protein,” as Yanker calls it, that was controlling all of this neural activity. Using computer algorithms, they narrowed the search down to a protein called REST, which research from Yanker’s lab has previously suggested could protect the brain from dementia.
“When we over-expressed, or turned up, this protein in the worm, the worm now, interestingly, reduced the amount of nervous system excitation and lived longer,” Yankner explains. “When we did the opposite, when we turned it down, we actually got more excitation and the worm lived a shorter lifespan.”
That finding, Yankner says, suggests that REST could be an effective target for drugs meant to combat neurodegenerative diseases like Alzheimer’s. Prior research has shown that, as Alzheimer’s progresses, patients have excessive neural activity in the hippocampus, the part of the brain where the disease often originates. Another trial out of Johns Hopkins showed early evidence that an anti-convulsive medication that suppresses neural excitation improves memory in patients with mild cognitive impairment. Finding the right balance between suppressing excessive neural activity, while preserving necessary function, would be tricky, Yankner concedes, but likely not impossible.
Aside from the promising avenues for drug research, Yankner says the work suggests habits and behaviors that affect the brain’s neural activity—like yoga and meditation—could potentially prolong lifespan. That’s a common idea in Eastern healing traditions, but one that has only recently infiltrated the Western medical establishment, he says.
It’s much too soon to prescribe a daily meditation session or yoga class based on these findings, but Yankner says the paper is a promising step toward understanding how “a person’s thoughts, personality and behavior affect their overall health and longevity.”