Stress leads to needless anxiety - things you should know

A new study reveals that stress can alter the way the brain forms memories, leading individuals to perceive threats even in safe environments.

In Short

• Stress can cause memory distortions by enlarging clusters of neurons in the brain
• Stress might make it difficult to differentiate between safe and fearful events
• Researchers are investigating treatments to remove stress-related memory disruptions

Stress can disrupt how the brain forms memories, causing people to feel threatened even in safe situations, according to a new study.

Researchers have found that stress makes clusters of neurons in the brain, called engrams, which grow larger, interfering with memory and amplifying fear.

This might help explain why people with conditions like PTSD (post-traumatic stress disorder ) or anxiety often feel unsafe in harmless environments.

For instance, after burning a finger on a hot pan, someone under stress might start avoiding not just the pan but the entire kitchen. This generalised fear is common in people dealing with post-traumatic stress disorder (PTSD) or anxiety.

The study, published in Cell, explored how stress impacts memory, focusing on the amygdala, the part of the brain that controls emotions and stress responses. Scientists worked with mice to understand this process.

HOW STRESS CHANGES MEMORY

In the experiments, some mice were stressed by raising their stress hormone levels. Later, they were exposed to two sounds: one neutral and one followed by a mild shock to mimic a fearful event. Unstressed mice remembered the difference between the two sounds, freezing only when hearing the sound linked to the shock.

But stressed mice froze at both sounds, showing they couldn’t tell the neutral event from the scary one.

Further tests showed that stressed mice formed larger engrams, memory bundles in the brain, than their unstressed counterparts.

Normally, the brain regulates engram size using a chemical called GABA, which acts like a bouncer at a club, letting only specific neurons in. But under stress, this mechanism fails, allowing more neurons to crowd into the engram, distorting memory.

POTENTIAL FOR TREATMENT

The researchers found that two drugs, including mifepristone, could reverse this effect in stressed mice by blocking the stress pathways in the brain.

However, these drugs would only work at the time the memory is formed and have other side effects, making them unlikely treatments for humans.

Scientists are now exploring whether memories can be adjusted after they’ve formed, potentially opening new doors to help those affected by stress-related memory issues.