Among the more intriguing aspects of the aging process that I’ve been noticing lately is how much more slowly I move now than in my younger years. Climbing in and out of the shower, navigating a staircase, even clearing dishes from the dinner table, I tend to travel from point A to point B with what sometimes strikes me as an odd sort of deliberation.
I like to think of it as a kind of mindfulness practice, one that may help me avoid an inadvertent tumble. Falling, after all, is a major cause of debilitating injury among the Medicare set. And, as I occasionally remind myself: What’s the hurry, anyway?
It’s not all about a particular mindset, obviously; there are physiological factors that slow us down as we grow old. Creaky joints, overtaxed muscles, and unreliable equilibrium all conspire to impede our speed. And as researchers at the University of Colorado Boulder recently noted, certain parts of our brains may play a role as well.
It’s no secret that our aging muscles work less efficiently — burning more calories — than those of younger people when performing the same task. By slowing our movements, seniors conserve energy. But Alaa Ahmed, PhD, and her team wondered whether older brains, which produce less dopamine than their younger counterparts, would cause seniors to respond less energetically to rewards. If you’re not feeling much of a dopamine rush, in other words, you’re less likely to move more quickly to trigger one.
The question, as Ahmed recently posed it in the Journal of Neuroscience, is a fairly straightforward one: “Is age-related slowing principally a consequence of increased effort costs from the muscles, or reduced valuation of reward by the brain?”
Her team recruited 80 study participants and separated them into two age groups: a younger cohort (18 to 35) and an older one (66 to 87). Stationed in front of a computer screen, each participant was instructed to move the cursor toward a target by manipulating the handle of a robotic arm. Some of the targets would explode with a bing bing sound when hit, and the study subjects would earn points.
Both groups hit the exploding targets more quickly than those lacking such a “reward,” but the younger participants did it by moving the arms faster while the seniors relied on their ability to anticipate the arrival of the targets. When researchers added an 8-pound weight to the robotic arms used by the young folks, it negated their speed advantage. So, they mimicked the seniors’ anticipatory strategies.
“The brain seems to be able to detect very small changes in how much energy the body is using and adjusts our movement accordingly,” explains study coauthor Robert Courter, PhD. “Even when moving with just a few extra pounds, reacting quicker became the energetically cheaper option to get to the reward, so the young adults imitated the older adults and did just that.”
All of which seems to suggest that it’s the increased “effort costs” of moving that slows us down as we age. But Ahmed admits that the brain’s reward centers cannot be dismissed as a potential influence. More research, as they say, will be required before we’ll have a clearer picture of the forces governing our movement challenges — and potential breakthroughs in the diagnosis of Parkinson’s, multiple sclerosis, and other similar diseases.
“Why we move the way we do, from eye movements to reaching, walking, and talking, is a window into aging and Parkinson’s,” she says. “We’re trying to understand the neural basis of that.”
While Ahmed and others delve more deeply into the mysteries of movement, I find myself less anxious for the next scientific breakthrough than with my ability to consistently embrace my slowness. Wherever I’m headed, I’ll get there eventually — and arriving safely is an ample reward.
