When children experience serious stress—like abuse, neglect, or lack of care—it can change how their brains grow.
This kind of stress can increase the risk of mental health problems later in life, such as depression, anxiety, and even schizophrenia.
Until recently, scientists didn’t fully understand how this happened or how to prevent it.
But on August 1, a team of researchers from KAIST (Korea Advanced Institute of Science and Technology), led by Professor Won-Suk Chung, made a major breakthrough.
They discovered that stress in childhood can cause certain brain cells called astrocytes to become overactive. These cells start removing too many connections between brain cells, which can harm the brain’s development.
The findings were published in the scientific journal Immunity.
Astrocytes usually have an important job in the brain. They help clean up waste and remove things the brain doesn’t need. But when a child is under too much stress for too long, this helpful process goes wrong.
Instead of just removing waste, the astrocytes start removing healthy connections between brain cells—specifically, the connections that allow brain cells to communicate.
The research showed that stress hormones produced by the body play a big role in this. These hormones attach to parts of the astrocytes called glucocorticoid receptors.
This causes the astrocytes to produce too much of a molecule called Mer tyrosine kinase, which tells them to start cleaning up—even things that shouldn’t be cleaned up.
To study this, the researchers used young mice that were kept isolated and not allowed to socialize. This early-life stress caused changes in their brains similar to what we see in people with mental health disorders.
The astrocytes in these stressed mice removed too many brain connections, especially in areas of the brain related to social behavior and emotion. As the mice got older, they showed signs of depression and had trouble with social interactions.
One surprising finding was that another kind of brain cell—called microglia—did not show the same behavior. Only the astrocytes reacted to the stress hormones by removing connections, which means they may be the key players in this process.
The team also tested the effect of stress hormones on human brain cells grown in the lab. They found the same thing: human astrocytes also started removing too many connections when exposed to stress hormones. This suggests that the same damaging process could happen in human brains under long-term stress.
Professor Chung said that this is the first time scientists have clearly shown how childhood stress might lead to mental illnesses later in life. He believes that future treatments could focus on controlling how astrocytes respond to stress, which might help prevent or treat mental health problems.
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