Depression is one of the most common mental health problems around the world. It is marked by long-lasting sadness, lack of interest in life, changes in sleep and appetite, and difficulty with everyday activities.
While many people know that stress can increase the chance of becoming depressed, scientists are still working to understand exactly how this happens inside the body.
Now, researchers in China from Wenzhou Medical University, Capital Medical University, and other institutions have discovered a possible link between stress and depression that involves a chemical called formaldehyde.
Their study, published in the journal Molecular Psychiatry, shows that high stress levels can cause the brain to produce more formaldehyde, which may interfere with normal brain functions and lead to depression.
Formaldehyde is a small, reactive chemical that is naturally made in the body during certain processes, such as when DNA or proteins break down. It is also found in the environment and is used in some building materials.
Previous studies have shown that being exposed to environmental formaldehyde can lead to symptoms of depression. However, it was not clear if formaldehyde made inside the body had the same effect.
In their study, the researchers looked at how stress affects formaldehyde levels in the brain, especially in a region called the hippocampus. This part of the brain is important for memory and emotional control and is often damaged in people with major depressive disorder (MDD), a severe form of depression.
To study this, the researchers used both mice and human subjects. In mice, they used a stress model called “chronic unpredictable mild stress,” which causes behaviors similar to depression in humans. They gave some of the mice extra formaldehyde to see if it would increase the signs of depression.
They also used advanced chemical tools called “probes” to measure the amount of formaldehyde in the mice’s brains. These tools glow when they find formaldehyde, which helps scientists track how much is present. They then recorded electrical signals in the hippocampus and measured key mood-related brain chemicals like serotonin, dopamine, and melatonin.
The results were very interesting. Mice exposed to stress or formaldehyde showed signs of depression.
The formaldehyde seemed to reduce the levels of serotonin, dopamine, and melatonin—three important chemicals that help regulate mood, motivation, sleep, and energy. These changes made the mice less active and more anxious, which are signs of depression. The hippocampus also showed damage, and the brain cells there became less active.
In addition to the animal tests, the researchers looked at brain scans of teenagers diagnosed with depression. They found shrinkage in the same part of the brain—the hippocampus—and lower levels of the same brain chemicals.
When they checked the blood of these patients, they also found higher levels of formaldehyde, which seemed to match the severity of their depression.
To confirm these findings, the team examined a large database of information about body chemicals in people with depression. They found more signs that formaldehyde may play a big role in how depression starts and worsens.
The researchers believe that when people go through stress, their brains may start to make more formaldehyde. This chemical then causes damage by lowering key brain chemicals and hurting brain structure, especially in the hippocampus. This may be one of the main reasons why stress can lead to depression.
This study opens the door to new ideas for treating or diagnosing depression. If future research confirms these results, doctors may one day be able to test formaldehyde levels to detect early signs of depression or develop ways to lower formaldehyde in the brain as a treatment.
In short, this research shows that formaldehyde—something most people think of as a chemical found in factories—could also be made inside our own brains during times of stress, and it might play a hidden but important role in causing depression.
If you care about health, please read studies that scientists find a core feature of depression and this metal in the brain strongly linked to depression.
For more health information, please see recent studies about drug for mental health that may harm the brain, and results showing this therapy more effective than ketamine in treating severe depression.
Copyright © 2025 Knowridge Science Report. All rights reserved.
