Brain size and shape can morph in response to stress, new study finds
The brain is a remarkable organ. It’s responsible for thoughts and feelings. It tells your muscles to move. It even can grow or shrink depending on what’s happening in your environment. Now a new study finds that going through tough times as a kid also can have an impact. That stress can change the size and shape of the brain.
The adult brains of people who lived through lots of stress before the age of six — and then became depressed or anxious as teenagers — were different than in adults who had an easier childhood. It seems that teens changed the shape of their brains by internalizing the stresses experienced years earlier — replaying those events in the mind and bottling up the emotions they triggered.
Researchers already knew that the shape and size of a child’s brain can change in response to lots of stress. They also knew that adults were more likely to be depressed if, as kids, they’d been abused, lived in poverty or faced other hard times.
Some studies showed that these depressed adults had unusual changes in their brain shape. But no one had tested if the early stress and later brain changes were linked.
Scientists in England studied almost 500 boys from birth until the ages of 18 to 21. Throughout those years, the boys’ moms answered questions about different types of stress their children had been experiencing. Had a parent died? Was the mother being abused? Was the family poor? Did the family pack up its belongings and move a lot? Once the boys reached adolescence, the list of questions began to also ask about whether the boys seemed sad, depressed or anxious.
Later, when the guys reached young adulthood, the research team created pictures of the structures in their brains using a technology known as MRI, for magnetic resonance imaging. The brain is mostly made up of white matter and gray matter. White matter acts like the brain’s subway system; it connects different areas of gray matter to each other, helping messages travel quickly.
Gray matter is what covers the brain’s surface. It’s gray in color and partly made of special cells called neurons. Gray matter helps process information in the brain, such as telling your muscles to pull your hand away if it touches a hot surface. The scientists focused on the amount of gray matter present.
Boys who’d had really tough lives before the age of six were more likely to be depressed or withdrawn as teenagers, the surveys showed. Those boys also were more likely to grow up with gray-matter changes, compared with others who had much less stressful childhoods.
In some regions of the brain, the volume of gray matter appeared to have shrunk. Another brain area showed what seemed to be a bonus amount of that gray matter.
And these changes weren’t random.
The superior frontal gyrus (JY-rus) is a part of the brain that some studies have linked with depression. In the new study, young men who had survived a stressful childhood and then later became very depressed or anxious as teenagers had less gray matter in this area.
Or at least they had less compared with the men whose early years had been more peaceful. The fact that the teenagers had internalized their emotions had been key, the researchers concluded.
But a different part of the brain had more gray matter than usual in the men who experienced early stress. Called the precuneus (pre-KEW-nee-us), this area has been linked to processing abuse and other harsh experiences. The scientists now wonder whether excess gray matter in the precuneus might be evidence of the brain trying to cope with that stress and abuse.
Learning from the new data
Sarah Jensen, one of the new study’s authors, works at King’s College London in England. There, she is studying to be a psychologist. The precuneus is involved in the brain’s “default mode,” she notes.
In healthy people, this default mode becomes active during daydreaming, mind wandering and self-reflection. But when the default mode isn’t working right, she says, it can be linked to depression.
Almost all of the boys her team studied experienced some hard times as kids. And, she concludes, “This is not necessarily harmful.” To some extent, that’s just life. What can be dangerous, she says, is when children experience too many forms of adversity. Her team’s new data suggest that the tougher the childhood, the stronger the impact on the brain might be.
Experiencing stress and internalizing problems have both been linked with having less gray matter, notes Ted Barker. He is a developmental psychologist at King’s College London. He also worked on the new study. His team’s analyses now point to how important it is for kids to talk to others if they’re feeling blue.
“I would say that if you feel that you have problems, you’re very anxious or have a lot of depressive-type thinking, that it’s good to talk to people,” Barker says. Indeed, he says, don’t keep problems bottled up inside.
What’s happening in the world around us relates to how we feel, he says. His team linked more childhood stress to more depression-like symptoms in young adulthood. Still, he notes, it’s possible that if you find support for anxiety or depression, you might be able to prevent the gray-matter changes seen here.
“If you can change the environment, you can change the course of things,” Barker says. So, he recommends, if teens develop anxiety or depression, “It’s good to ask for help.”