Imaging studies show we should give ourselves a break
By: Laura Sanders
I’m on deadline, but instead of focusing, my mind buzzes with unrelated tidbits. My first-grader’s tablet needs an update before her online school session tomorrow. Heartbreaking deaths from COVID-19 in New York City make me tear up again. Was that a kid’s scream from upstairs? Do I need to run up there, or will my husband take care of it?
These hornets of thoughts drive out the clear thinking my job demands. Try as I might to conjure up a coherent story, the relevant wisps float away.
I’m scattered, worried and tired. And even though we’re all socially isolated, I’m not alone. The pandemic — and its social and economic upheavals — has left people around the world feeling like they can’t string two thoughts together. Stress has really done a number on us.
That’s no surprise to scientists who study stress. Our brains are not built to do complex thinking, planning and remembering in times of massive upheaval. Feeling impaired is “a natural biological response,” says Amy Arnsten, a neuroscientist at Yale School of Medicine. “This is how our brains are wired.”
Decades of research have chronicled the ways stress can disrupt business as usual in our brains. Recent studies have made even more clear how stress saps our ability to plan ahead and have pointed to one way that stress changes how certain brain cells operate.
Scientists recognize the pandemic as an opportunity for a massive, real-time experiment on stress. COVID-19 foisted on us a heavy mix of health, economic and social stressors. And the end date is nowhere in sight. Scientists have begun collecting data to answer a range of questions. But one thing is clear: This pandemic has thrown all of us into uncharted territory.
The human brain’s astonishing abilities rely on a web of nerve cell connections. One hub of activity is the prefrontal cortex, which is important for some of our fanciest forms of thinking. These “executive functions” include abstract thinking, planning, focusing, juggling multiple bits of information and even practicing patience. Stress can muffle that hub’s signals, studies of lab animals and humans have shown.
“Even relatively mild stress can impair the prefrontal cortex,” says Elizabeth Phelps, a psychologist and neuroscientist at Harvard University. “That’s one of the most robust effects of stress on the brain.”
That impairment has been described in lots of studies. One memorable example comes from 20 panicky medical students facing licensing exams. After a month of high-stress test prep, the students performed worse on an attention test than they did after exams were over. Functional MRI scans showed that under stress, the students’ prefrontal connections to other brain areas were diminished, scientists reported in Proceedings of the National Academy of Sciences in 2009.
When the prefrontal cortex goes quiet, more reactionary brain networks take over. Some of these “primitive” circuits, as Arnsten calls them, center on the amygdalae, two almond-shaped structures buried deep inside the brain that help us sense and respond to threats. Those fast, instinctual reactions “are helpful if you’re being faced with a snake,” Arnsten says, “but not helpful if you’re being faced with a complex medical decision.”
A more recent experiment, published online April 2 in Current Biology, illustrates how stress can shift people away from thoughtful planning. When people were threatened with electric shocks, their abilities to plan ahead flew out the window. Anthony Wagner, a cognitive neuroscientist at Stanford University, and colleagues asked 38 people to learn a familiar route through virtual towns. With practice, people learned these routes, as well as the locations of recognizable objects, such as a zebra, an apple, a stapler or Taylor Swift’s face, along the way.
“Our question was, ‘What are the effects of stress?’ ” Wagner says. To find out, the researchers used “moderately painful” electric zaps to induce stress in some participants, who returned to familiar virtual towns and were asked to find their way to the zebra, for instance. Subjects didn’t know when they would be shocked, and they couldn’t control any aspect of it.