Childhood stress can leave changes in the adult brain

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.

Until now.

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Boys who’d had really tough lives before the age of six were more likely to be depressed or withdrawn as teenagers, the surveys showed.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.”

His team’s study appeared August 17 in JAMA Pediatrics.

Power Words

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anterior cingulate cortex  A part deep inside the brain located right between the eyes. This strip of neurons (nerve cells) surrounds a large white ridge in the center of the brain. The anterior cingulate cortex is important in many functions, including helping to regulate your blood pressure. But it also plays cognitive roles too, helping us with decision-making, controlling impulses, regulating emotions and the intensity of our feelings for other people.

anxiety  (adj. anxious) A nervous disorder causing excessive uneasiness and apprehension. People with anxiety may even develop panic attacks.

depression (adj. depressive) A mental illness characterized by persistent sadness and apathy. Although these feelings can be triggered by events, such as the death of a loved one or the move to a new city, that isn’t typically considered an “illness” — unless the symptoms are prolonged and harm an individual’s ability to perform normal daily tasks (such as working, sleeping or interacting with others). People suffering from depression often feel they lack the energy needed to get anything done. They may have difficulty concentrating on things or showing an interest in normal events. Many times, these feelings seem to be triggered by nothing; they can appear out of nowhere.

development  (adj. developmental) The growth of an organism from conception through adulthood, often undergoing changes in chemistry, size and sometimes even shape.

gray matter  One of two main types of tissue found in the brain and spinal cord. It consists mainly of nerve cell bodies.

internalize  (in psychology) To hold thoughts or emotions inside and not talk about them. To ruminate over the bad things, such as the loneliness, the fears or the sad feelings one has.

magnetic resonance imaging (MRI)  An imaging technique to visualize soft, internal organs, like the brain, muscles, heart and cancerous tumors. MRI uses strong magnetic fields to record the activity of individual atoms. 

neuron or nerve cell  Any of the impulse-conducting cells that make up the brain, spinal column and nervous system. These specialized cells transmit information to other neurons in the form of electrical signals.

organ    (in biology) Various parts of an organism that perform one or more particular functions. For instance, an ovary is an organ that makes eggs, the brain is an organ that interprets nerve signals and a plant’s roots are organs that take in nutrients and moisture.

precuneus    This is a part of the brain located towards the back and just to either side of the big central part that runs beneath the top of your scalp from front to back. It’s between our major sensory cortex (which processes touch) and our main visual cortex (which processes sight). The precuneus is involved in many important things including consciousness, memory and even our sense of self.

psychology  The study of the human mind, especially in relation to actions and behavior. Scientists and mental-health professionals who work in this field are known as psychologists.

stress (in biology) A factor, such as unusual temperatures, moisture or pollution, that affects the health of a species or ecosystem. (in psychology) A mental, physical, emotional, or behavioral reaction to an event or circumstance, or stressor, that disturbs a person or animal’s usual state of being or places increased demands on a person or animal; psychological stress can be either positive or negative.

superior frontal gyrus  This is a part of the brain located behind the forehead. It’s involved in higher-level thinking, memory and laughter.

white matter  One of the two main tissue types found in the brain and spinal cord. It consists mainly of bundles of nerve fibers.