The Hidden Reason Some Brains Can’t Let Go of Anxiety

In our previous pieces, we explored the biological roots of anxiety—step by step: from the early body signals in “Anxiety Doesn’t Speak—It Hides in the Body: 10 Signals to Watch For”, to the stuck alarm system in “Anxiety Isn’t Just in Your Mind: When the Brain Forgets to Turn Off the Alarm”, and then to the transition from anxiety to disorder in “From Anxiety to Anxiety Disorder: When the Brain Turns Fear into Habit”.

We now know anxiety isn’t weakness—it’s a protection system that got stuck “on.” Which raises a crucial question: Why do some people calm down quickly, while others get pulled back into anxiety again and again? In this article, we’ll go deeper into how genetics, sleep, blood sugar, hormones, and early-life stress can make the brain more likely to “remember anxiety.”

Ⅰ. Evolutionary Perspective: Why Anxiety Was Preserved

Imagine early humans tens of thousands of years ago— a rustle in the grass at night, some stayed asleep without concern, while others’ hearts raced, instantly alert. In that world, who was more likely to survive? The answer is clear: those who reacted quickly and felt anxious easily.

Scientists call this mechanism adaptive anxiety. In prehistoric environments full of threats, people with more sensitive amygdalas detected risks earlier, and their genes were passed down through generations. This means that the “anxiety circuitry” within us today is the result of millions of years of natural selection.

The problem is—modern danger has changed.
Once it was predators, hunger, and cold; now it’s emails, bills, relationships, and uncertainty. Yet the brain’s alarm system hasn’t learned to tell the difference. It still sounds the alarm for a meeting, a message, or a careless comment.

And so, the very mechanism that once saved us now fuels anxiety, insomnia, and imbalance. Anxiety disorders don’t mean we’ve grown weaker— they mean our biological programming is out of sync with the pace of modern life.

Ⅱ. Genetics and Brain Structure: The “Innate Code” of Anxiety

Scientific research has shown that some people are born with a more “alert” nervous system— not because of personality, but due to a combination of genes and brain structure.

Twin studies reveal that the heritability of anxiety disorders is around 30%–40%. In other words, more than one-third of a person’s tendency toward anxiety may be inborn.

One of the most discussed genes is 5-HTTLPR (the serotonin transporter gene). Individuals who carry the “short allele” variant have less efficient serotonin reuptake, and their amygdala reacts more strongly under stress. This means they have a lower emotional alarm threshold— even small environmental changes can easily trigger an anxious response.

Beyond genetics, structural differences in the brain also play a key role:

• Larger amygdala volume is associated with heightened fear and vigilance;
• Thinner prefrontal cortex may weaken emotional regulation and self-control;
• Reduced hippocampal activity makes it harder to distinguish between real and imagined threats.

Therefore, people who are more prone to “remembering anxiety” are not less resilient— their brains are simply wired to be more sensitive and responsive to stress signals on a biological level.

Ⅲ. Early Stress and Neuroplasticity: The "Memory Trace" of Anxiety

Genetics may make some people naturally more sensitive, but early experiences determine whether that sensitivity is soothed—or amplified. For the brain, childhood stress is never truly “forgotten”; it becomes wired into neural connections and serves as a template for future emotional responses.

During the first decade of life, the brain undergoes its most active phase of neuroplasticity— the amygdala, hippocampus, and prefrontal cortex are constantly forming new connections. If a child grows up amid tension, neglect, conflict, or loss, the brain “matures early” into a high-alert circuit, prioritizing survival over the feeling of safety.

How Early Stress Shapes the Brain

Neuroimaging studies show that adults who experienced early adversity often display the following structural changes in the brain:

• Enlarged amygdala: heightened sensitivity to threat and faster fear responses;
• Underdeveloped prefrontal cortex: weaker top-down regulation of anxiety impulses;
• Reduced hippocampal volume: diminished ability to store “safe” contextual memories.

These changes are not mere “psychological shadows” but visible neural remodeling. In other words, anxiety doesn’t arise out of nowhere— it’s a survival strategy that the developing nervous system once learned under stress.

Neuroplasticity: Anxiety Can Be Rewritten

Neuroplasticity also means hope. Even if these pathways were “wired in” during childhood, the brain can still form new, healthier circuits through deliberate practice and care.

• Regular sleep and exercise help restore cortisol rhythm;
• Mindfulness and psychotherapy strengthen prefrontal regulation;
• Balanced nutrition and emotional support promote hippocampal regeneration.

IV. Environment & Daily Rhythms: Anxiety’s “Accelerator”

Genes set the brain’s baseline “sensitivity,”
but what truly accelerates anxiety is your daily pace.
When sleep, diet, hormones, and stress rhythms are disrupted,
the brain misreads the world as if danger never left.

1) Sleep: The Brain’s “Braking System” Unplugged