Written by
Louise W Lu, PhD, MPH, BMLS
Written/Reviewed by
Alexandra V Goldberg, Registered Dietitian
Remember what we discussed in the previous article “Anxiety Is Not Just in Your Mind: When the Brain Forgets to Turn Off the Alarm”?
At its core, anxiety is the brain’s “alarm system” designed to protect you. But when this system forgets how to switch off, the body gets trapped in a constant “fight-or-flight” state.
Earlier, in “Anxiety Doesn’t Speak — It Hides in the Body: 10 Signals to Watch For”, we looked at anxiety’s earliest signs — palpitations, sweating, bloating, tight muscles, sleepless nights… Those “little problems” are really the body paying the price for psychological overload.
anxiety stops being a temporary “feeling,”
and becomes a conditioned reflex — a habit the brain remembers.
In this article, we’re going one layer deeper:
How does anxiety disorder gradually become “fixed” within the nervous system?
Why do some people move out of anxiety,
while others get stuck in an endless loop?
The answer lies in the brain’s “learning mechanisms” —
when the amygdala, prefrontal cortex, and cortisol interact repeatedly,
anxiety becomes a memory stored by the nervous system.
The Brain’s Survival Logic: Why Anxiety Is a Protective Response
Imagine this scene:
Long, long ago, deep in the ancient forest,
one of our human ancestors hears a rustling sound in the bushes.
Before they can even see what it is, the brain immediately presses the alarm button —
heart pounding, breathing quickening, muscles tightening, pupils widening.
It might just be the wind... but if it’s a predator,
that one-second reaction could mean the difference between life and death.
It’s a built-in “early warning system” the brain designed for us —
to prepare us before danger actually arrives.
The “commander” of this system is a tiny structure deep in the brain — the amygdala.
It works like a vigilant guard, constantly scanning for signs of danger.
Once it senses something might be risky, it sounds the alarm:
it signals the hypothalamus to coordinate the body’s response, while the adrenal glands release adrenaline.
Soon after, the body releases cortisol to sustain the state of alertness.
Within seconds, the entire “defense system” of the body ignites —
the heart beats faster, sending blood to the limbs for quick escape;
breathing speeds up, filling the lungs with oxygen;
digestion shuts down, because now is “not the time to eat”;
and the skin starts to sweat, cooling the body to prevent overheating.
This whole chain reaction is the body’s automatic survival program,
initiated by the amygdala and carried out through the sympathetic nervous system and cortisol.
In the short term, it can save your life;
but if it stays switched on for too long,
it becomes the root of chronic anxiety.
Today, our “dangers” are no longer wild beasts — but meetings, bills, relationships, and uncertainty about the future.
Yet the amygdala doesn’t know the difference.
It still faithfully sounds the alarm, keeping us in a state of constant small stress —
until we slowly become a machine that never relaxes.
your brain is trying to protect you —
yet in doing so, it traps you in a constant state of readiness.
Ⅱ. When Fear Becomes an “Auto-Program”: The Neural Model of Anxiety
Each bout of anxiety further strengthens neural connections.
Over time, this “fear memory” is repeatedly reinforced in the brain, shifting from a temporary emergency pathway into an automated neural program.
When anxiety is no longer brief stress but a persistent state, it’s as if the brain’s “auto-run” button is pressed.
A closed loop forms among the amygdala, hypothalamus, and adrenal glands, causing fear signals to circulate repeatedly in the body— keeping you on high alert even without real external danger.
Physiologically, this loop is the HPA axis (Hypothalamus–Pituitary–Adrenal).
When the amygdala signals “danger,” the hypothalamus cues the pituitary to activate the adrenals, releasing cortisol and norepinephrine.
They sustain vigilance: faster heart rate, higher blood glucose, rapid breathing.
With repeated activation, cortisol in turn sensitizes the amygdala, forming a self-reinforcing anxiety loop.
From a neurochemical view, compared with ordinary (situational) anxiety, anxiety disorders more often show three imbalances:
- Elevated cortisol — keeps the body tense and fatigued;
- Overactive norepinephrine — intensifies palpitations, sweating, panic;
- Low serotonin — reduces mood stability and sleep quality.
Compared with a healthy state, the activity pattern of an anxiety-disorder brain differs markedly:
| Status | Amygdala Activity | Prefrontal Activity | Physiological Pattern |
|---|---|---|---|
| Healthy Brain | Brief activation, settles quickly | Effectively inhibits overreaction | Returns to calm soon after stress |
| Anxiety-Disorder Brain | Persistently overactive, hypersensitive | Reduced inhibitory control | Chronic palpitations, muscle tension, insomnia, dyspepsia |
III. Mechanisms of Anxiety Formation and Psychological Classification (DSM-5 Framework)
When anxiety evolves from a temporary defensive response into a persistent mind–body condition, it enters the realm of Anxiety Disorders as defined by psychology and psychiatry.
Anxiety disorders are a group of conditions characterized by excessive fear, tension, or anticipatory anxiety.
These emotional responses are disproportionate to actual threats, typically lasting for more than six months,
and result in significant physical symptoms or social dysfunction.
DSM-5 divides anxiety disorders into multiple subtypes, each representing a different way in which the brain and body become “trapped in the anxiety loop.” Below are four of the most common types, their causes, and typical examples:
① Generalized Anxiety Disorder (GAD)
Features: persistent worry, inability to stop overthinking, and excessive tension about everyday matters. Patients often feel anxious “for no specific reason” and wake up with unease.
Common symptoms: chest tightness, stomach discomfort, muscle tension, and shallow sleep. Psychologically, there is constant anticipation of “the worst outcome,” making relaxation difficult.
Example: Ms. L wakes up every morning feeling panicky. Although everything seems normal, her mind keeps imagining scenes like “something bad might happen today” or “the client might get angry.” She knows these worries are irrational, but her body can’t stop responding.
Cause: chronically elevated cortisol reduces the prefrontal cortex’s ability to regulate emotions, while the amygdala becomes hypersensitive, keeping the brain constantly “searching” for threats.
② Panic Disorder
Features: sudden and intense fear, often occurring without warning. After one episode, the individual develops a strong fear of “it happening again.”
Common symptoms: rapid heartbeat, chest tightness, sweating, dizziness, shortness of breath, and a sense of impending doom. Many sufferers avoid being alone or going out due to this fear.
Example: Mr. W suddenly experiences a pounding heart and shortness of breath while checking out at a supermarket. He feels like he’s going to faint or have a heart attack. Hospital tests show nothing abnormal, yet the “fear of dying” makes him avoid crowded places afterward.
Cause: the amygdala and brainstem sympathetic system become overactive, misinterpreting minor bodily sensations (such as heartbeat or breathlessness) as life-threatening danger.
③ Social Anxiety Disorder
Features: fear of others’ evaluation, scrutiny, or rejection. In social settings, individuals worry about “embarrassing themselves” or “being rejected.”
Common symptoms: blushing, shaking hands, sweating, and trembling voice. Over time, this can lead to social avoidance and isolation.
Example: During class presentations, student X blushes, trembles, and feels his heart race whenever classmates look at him. Eventually, he prefers skipping class to avoid public speaking.
Cause: the amygdala becomes overly sensitive to social cues; combined with excessive self-awareness and limited social experience, the brain mistakes “being seen” as a danger signal.
④ Post-Traumatic Stress Disorder (PTSD)
Features: after experiencing major trauma, memories become “stuck in time.” The brain cannot distinguish between “past” and “present,” and once triggered, the fear scene replays vividly.
Common symptoms: nightmares, sudden awakenings, irritability, avoidance of specific situations, sometimes accompanied by memory confusion and emotional numbness.
Example: After a car accident, Ms. Z feels tense and her heart races whenever she hears screeching brakes. She knows she’s safe, but can’t control her fear, and often wakes from nightmares.
Cause: the amygdala remains hypersensitive to traumatic memories, while hippocampal shrinkage prevents proper “filing” of these memories, making the brain believe the trauma is still happening.
Regardless of type, the root of anxiety disorders points to a shared mechanism: when the brain loses the ability to accurately distinguish between threat and safety, fear becomes “misstored” and turns into a habitual response.
IV. Why Some People Are More Likely to “Remember Anxiety”
Why can some people recover from stress within days, while others fall into prolonged anxiety and insomnia? This isn’t a matter of willpower — it’s because the brain’s plasticity and lifestyle rhythms together determine whether you are more likely to “remember anxiety.”
Genetics and Neural Sensitivity
Some individuals are born with higher amygdala activity and a more fragile balance of neurotransmitters. Genetic factors influence how dopamine, serotonin, and norepinephrine are regulated. This “highly sensitive nervous system” allows them to detect danger more quickly, but also makes it harder to recover from anxiety.
Environment and Circadian Rhythm
Sleep deprivation, blood sugar fluctuations, chronic caffeine intake, and hormonal cycles in women can all disrupt the body’s cortisol rhythm. When the body’s circadian rhythm is disturbed, the brain struggles to distinguish “safe” from “dangerous.”
Early Experiences and Neural Plasticity
Prolonged exposure to high-stress environments during childhood or adolescence — such as criticism, conflict, or emotional neglect — can alter neural plasticity. The amygdala becomes “trained” to be hypervigilant, while the hippocampus has more difficulty storing “safety memories.” As a result, the adult nervous system is more prone to becoming “stuck” in a stress response.
Understanding how it forms is the first step toward “retraining the brain.” In the next article of this series, we’ll explore scientific methods to break the cycle of anxiety and rebuild inner calm.
