What Causes Anxiety Attacks? Genetics, Brain Chemistry, and Life Factors

Short Answer

What causes anxiety attacks is not one single trigger. Anxiety develops when inherited risk, temperament, brain threat circuitry, stress load, and life experience interact. The body matters, too: thyroid problems, heart-rhythm issues, low blood sugar, caffeine, alcohol, nicotine, and some medications can mimic or worsen anxiety-like feelings. A clinician can help rule out physical causes.

What causes anxiety — at a glance

How the anxious brain works — the threat-response system

The clearest way to understand anxiety's biology is as a threat-response system that has become too reactive, too persistent, or too hard to switch off.

The major anxiety disorders — as one large genetic study describes them — "(ANX; including generalized anxiety disorder, panic disorder and phobias) are highly prevalent, often onset early and cause substantial global disability" (Nature Genetics anxiety GWAS, 2026). They can look different from person to person — constant worry, panic, phobias, avoidance — but they "probably represent differential expressions of a dysregulated threat-response system" (same study).

That system is supposed to protect you. When your brain detects danger, it prepares your body to act. Your attention narrows. Your muscles tense. Your heart may speed up so blood and oxygen can move quickly. In a real threat, this is useful.

At the brain-and-body level, "the acute stress response activates the amygdala, hippocampus, and prefrontal cortex, stimulating the HPA axis and triggering cortisol release" (Frontiers in Cellular Neuroscience, 2026). After the threat passes, feedback loops are supposed to quiet the system down.

Anxiety becomes more likely when that recovery process does not work well. Research on stress biology describes how "chronic stress or exposure to severe stressors leads to sustained HPA axis activation, amygdala hyperreactivity, and immune dysfunction, all of which promote the development of anxiety disorders" (Frontiers in Cellular Neuroscience, 2026).

So the racing heart, dread, restlessness, and hypervigilance are not character flaws. They are body outputs from an alarm system that is running too hot.

At the chemical level, anxiety is not explained by one "bad" molecule. Comorbidity research describes anxiety-related symptoms as emerging through "the interplay of multiple mechanisms, including neuroinflammation, metabolic abnormalities, the hypothalamic-pituitary-adrenal (HPA) axis dysregulation, and imbalances in central neurotransmitter systems" (Frontiers in Neuroscience, 2026).

GABA — one of the brain's main calming signals — is part of this picture. The largest genetic study of anxiety to date "highlighted GABAergic signaling as one potential mechanism implicated in ANX genetic risk" (Nature Genetics anxiety GWAS, 2026). That does not mean "low GABA causes anxiety" in a simple way. It means GABA-related signaling appears to be one pathway in a larger, dysregulated system.

Is anxiety genetic? What the family and DNA evidence shows

Anxiety can run in families. But genes are not destiny, and there is no single "anxiety gene."

The strongest recent DNA evidence comes from a "genome-wide association meta-analysis comprising 122,341 European ancestry ANX cases and 729,881 controls" (Nature Genetics anxiety GWAS, 2026). The study "identified 58 independent genome-wide significant risk variants and 66 genes with robust biological support" (same study).

Those numbers point to a polygenic pattern: many genetic variants, each contributing a small amount to risk. The same study also found that anxiety shares inherited liability with nearby mental-health traits: "As predicted by twin studies, we found substantial genetic correlation between ANX and depression, neuroticism and other internalizing phenotypes" (same study).

That overlap matters. It helps explain why anxiety and depression so often appear together, and why a person with an anxious temperament may also be more vulnerable to low mood under stress.

Twin research suggests that genes explain a meaningful part of anxiety-disorder risk — commonly summarized as roughly a third to just over half (heritability estimates of about 30–60% in twin studies), with the rest driven by environment and experience (Genetics of Anxiety and Trauma-Related Disorders review, NIH).

Genetics also shows up in the way anxiety clusters with other conditions. Genomic work notes that "Fibromyalgia, insomnia, depression, and anxiety share common clinical comorbidities, but their underlying genetic architecture and mechanism remain unclear" (PLoS Genetics, 2026). The practical takeaway is simple: family history can raise your baseline risk, but it does not diagnose you, and it does not decide your future.

Temperament and early life — the risk factors that set the stage

Genes can influence how your nervous system responds to the world. One way that can show up is temperament.

Researchers often discuss behavioral inhibition: a cautious, watchful, threat-sensitive style that can be visible early in childhood, especially in unfamiliar situations. Behavioral inhibition is best understood as a risk marker, not a stand-alone cause. It may make anxious responses more likely, but it does not mean a child will inevitably develop an anxiety disorder — in fact, most children with this temperament do not (behavioral inhibition as a childhood risk factor for anxiety, PubMed).

Early-life stress and adversity matter, too. Adverse childhood experiences, maltreatment, and trauma are consistently discussed as anxiety risk factors because they may tune the stress system toward faster alarm and slower recovery (childhood adversity and vulnerability to anxiety, PubMed). That fits the HPA-axis and amygdala model above: the body learns what kind of world it is living in, and sometimes it learns to stay guarded.

This needs a careful frame. Many people with difficult childhoods do not develop anxiety disorders. Many people with anxiety had no obvious early trauma. Risk factors raise probability; they do not write a script.

Chronic stress — how "normal" stress can tip into anxiety

Stress is not the same as an anxiety disorder. Stress is a response to pressure. Anxiety is what can happen when the alarm keeps firing, even when the threat is unclear, distant, or gone.

In a healthy stress response, your body mobilizes and then recovers. Cortisol rises, attention sharpens, and your heart rate may increase. Later, the system settles. But when stress is constant — caregiving, money worries, workplace pressure, illness, unsafe environments, sleep loss — recovery gets harder. The brain can start treating ordinary uncertainty as danger.

That is why anxiety often builds gradually. You may not notice one dramatic trigger. You may only notice that your sleep is lighter, your patience is thinner, your body feels wired, and your heart seems louder than usual.

This is also where body signals can be useful as context. Trends in sleep, resting heart rate, heart-rate variability (HRV), and stress load may help you notice when your system is under strain. They do not diagnose anxiety or tell you the cause, but they can make a hidden pattern easier to discuss with a clinician.

From Welltory's own data:

Among Welltory users who self-report feeling anxious (n = 952, wearable-quality data), a single daily reading does not separate them from users who don't (n = 3,193): the morning HRV score is nearly identical (median 3.07 vs 3.09; about 88% distribution overlap), and a small resting-heart-rate gap (about +1 bpm) disappears once we account for how many health conditions people report. The useful signal for anxiety is not one number versus a population — it is how your own baseline shifts over time. This is a self-reported mood check, not a clinical anxiety diagnosis; all figures are reported as anonymized, aggregated data, and no individual user is identifiable.

What causes anxiety in the brain — and what chemical is involved

Two common questions are: what causes anxiety in the brain? and what chemical in the brain causes anxiety?

The honest answer is that there is no single location and no single chemical.

Anxiety is generated by a network involving the amygdala, hippocampus, and prefrontal cortex, coordinated with the HPA stress axis. The amygdala helps detect threat. The hippocampus helps place experiences in context and memory. The prefrontal cortex helps evaluate risk and regulate the alarm. When the system is balanced, it helps you respond and recover. When it is dysregulated, the alarm can stay active too long or fire too easily.

Neurochemistry is also network-based. GABA is repeatedly implicated as one calming pathway, including in the large anxiety GWAS above. Serotonin and noradrenaline are also involved in anxiety-related signaling, which is why some evidence-based anxiety treatments act on those systems. But "chemical imbalance" is too simple. Current evidence supports a dysregulated threat-and-stress system, not one broken chemical switch.

Can a physical problem cause anxiety? Somatic and substance causes

Sometimes anxiety-like symptoms start in the body. That does not make them "less real." It means the cause may be medical, substance-related, or mixed — and the safest next step is to rule out physical contributors with a clinician.

Thyroid and hormonal conditions

An overactive thyroid can speed up body systems and produce symptoms that feel like anxiety: a racing heart, sweating, tremor, heat intolerance, restlessness, or a wired feeling. Other hormonal shifts may also affect mood, sleep, and arousal. These problems are often treatable once identified, which is why persistent physical-feeling anxiety is worth discussing with a doctor rather than self-diagnosing (anxiety in patients with hyperthyroidism, NIH).

Heart rhythm, palpitations, and the anxiety loop

Heart symptoms and anxiety can amplify each other. Anxiety can raise heart rate and make you more aware of palpitations. A true rhythm problem can also feel like anxiety because it may cause pounding, fluttering, breathlessness, dizziness, or fear.

People often ask whether can atrial fibrillation be caused by anxiety, whether can anxiety cause AFib on Apple Watch, or whether can wearing a heart monitor cause anxiety. Research describes a two-way relationship between anxiety and atrial fibrillation (bidirectional association, PubMed). A wearable alert or monitor reading can understandably make you worried. But an alert is not a diagnosis, and anxiety is not the same as atrial fibrillation. Recurring palpitations, fainting, chest pain, or an abnormal rhythm notification should be evaluated by a clinician.

Caffeine, alcohol, nicotine, medications, and supplements

Substances can change how anxious your body feels. Caffeine is a stimulant and can provoke jitteriness, a fast heartbeat, and anxious sensations, especially at higher doses or in sensitive people (caffeine intake and anxiety meta-analysis, NIH). Alcohol and nicotine may feel calming in the short term but can worsen anxiety for some people over time, including as they wear off (alcohol, nicotine, caffeine, and mental disorders, NIH). Some medications can also list anxiety, agitation, palpitations, or sleep disruption as possible side effects.

People also ask: does L-theanine cause anxiety? Current research usually studies L-theanine for a calming effect rather than as an anxiety trigger (psychotropic effects of L-theanine, PubMed), but this should still be framed carefully. Any substance that affects sleep, heart rate, alertness, or mood can change how anxious you feel. If symptoms started after a new supplement, medication, or dose change, talk with the prescribing clinician or pharmacist.

What causes anxiety and depression together

Anxiety and depression often travel together because their risk factors overlap.

Part of that overlap is genetic: the large anxiety GWAS found substantial genetic correlation between anxiety, depression, neuroticism, and other internalizing traits. Part of it is biological: both conditions can involve stress-system dysregulation, sleep disruption, inflammation-related pathways, and changes in neurotransmitter signaling. Part of it is experiential: chronic stress, loss, trauma, illness, and prolonged uncertainty can push the same person toward both worry and low mood.

This does not mean anxiety always becomes depression, or depression always causes anxiety. It means the systems are connected. If you are dealing with both, it is reasonable to bring both up in care rather than treating them as separate problems.

Comparison blocks for quick extraction

Anxiety the emotion vs an anxiety disorder

Anxiety is a normal alarm response. It helps you notice danger, prepare, and act.

An anxiety disorder is different. The fear or worry is excessive, persistent, hard to control, or disruptive to daily life. The alarm system is no longer just responding to threat; it is interfering with sleep, work, relationships, decisions, or basic routines.

Psychological anxiety vs a physical somatic cause

Most anxiety involves the brain's threat system plus life context: genetics, temperament, stress, learning, sleep, and experience. But some physical conditions can mimic or trigger anxiety-like symptoms.

That difference matters. Hyperthyroidism, arrhythmias, low blood sugar, respiratory problems, medication effects, and stimulant use may need medical evaluation. New, intense, or physical-feeling symptoms should not be self-diagnosed as "just anxiety."

Genes vs environment

Genes and environment are not competing explanations. They work together.

Genes can set predisposition. Environment and experience influence whether, when, and how that predisposition shows up. Stress, early adversity, sleep loss, substances, physical illness, social support, and treatment access can all change the course.

Who needs extra caution / when to see a clinician

Talk to a clinician if anxiety is persistent, distressing, or interfering with work, sleep, relationships, or daily life. Anxiety is common, and it is treatable.

Seek immediate medical attention to rule out a physical cause if anxiety-like symptoms come with chest pain, fainting, a very fast, irregular, or pounding heartbeat, unexplained weight loss, tremor, severe shortness of breath, or symptoms that began after a new medication or substance.

If you are in crisis or thinking about harming yourself, contact your local emergency number now, or in the US call or text 988 (Suicide & Crisis Lifeline).

A wearable can help you notice patterns in stress, sleep, resting heart rate, and HRV. It cannot diagnose anxiety or identify the cause on its own.

How we made it

Made with AI tools, then edited, fact-checked, and medically reviewed by the Welltory team.

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