Anxiety disorders don’t have a single cause. They develop from a combination of genetic vulnerability, brain chemistry, life experiences, and ongoing stress, with different factors weighing more heavily for different people. Understanding what contributes to an anxiety disorder can help you make sense of your own experience and recognize what’s within your control.
Genetics Set the Starting Point
Your genes play a significant role in whether you develop an anxiety disorder, but they don’t seal the deal. Twin studies on generalized anxiety estimate that genetic factors account for roughly 39 to 46% of the variation in anxiety at any given point in time. When researchers tracked people over several years and looked at persistent, stable anxiety (the kind that doesn’t come and go), heritability jumped to about 60%. In other words, the more chronic your anxiety tendency, the stronger the genetic component likely is.
This doesn’t mean there’s a single “anxiety gene.” Multiple genes contribute small effects, influencing things like how your brain processes fear, how quickly your stress response activates, and how efficiently your body calms back down. Having a parent with panic disorder or major depression also raises a child’s risk, particularly for social anxiety.
What Happens in the Brain
Your brain has a built-in alarm system centered on the amygdala, a small structure that detects threats and triggers fear responses. In anxiety disorders, the communication between this alarm system and the prefrontal cortex (the part of the brain responsible for rational thinking and emotional regulation) becomes disrupted. Normally, the prefrontal cortex can quiet the amygdala once a threat passes. In people with anxiety, this calming signal is weaker or less consistent, so the alarm keeps firing even when there’s no real danger.
Three chemical messengers are especially important here. GABA is the brain’s primary calming signal, working to slow down neural activity. Glutamate does the opposite, ramping up excitation. Anxiety is thought to stem partly from an imbalance between these two systems, with too much excitation and not enough inhibition. Serotonin, which helps regulate mood and emotional responses, also plays a central role. Most first-line medications for anxiety work by boosting serotonin’s availability or enhancing GABA’s calming effects.
Stress makes these imbalances worse. Animal research shows that stress directly stimulates glutamate release in the prefrontal cortex, which can overwhelm the brain’s ability to regulate emotions and may explain why anxious people feel mentally “stuck” on threats they rationally know aren’t dangerous.
Childhood Experiences and Trauma
Adverse childhood experiences, sometimes called ACEs, are one of the strongest environmental predictors of anxiety disorders. These include physical or emotional abuse, neglect, household dysfunction like parental substance use or divorce, and exposure to violence. A large study of children and adolescents ages 8 to 17 found that those exposed to four or more ACEs had 1.7 times the odds of developing anxiety compared to children with fewer adversities. During middle childhood specifically, four or more ACEs were associated with 7.3 times higher odds of anxiety or depression.
The relationship between adversity and anxiety follows a dose-response pattern: the more ACEs a child accumulates, the greater the risk. Even at a threshold of two or more adverse experiences, the odds of anxiety were already 1.8 times higher than for children with fewer than two. This isn’t about one bad day. It’s about sustained or repeated exposure to stress during the years when the brain is still learning how to process threats.
How Chronic Stress Rewires Your Stress Response
Your body has a stress system (often called the HPA axis) that releases cortisol when you face a threat. Under normal conditions, cortisol surges briefly, helps you respond, and then the system shuts itself off through a feedback loop. Chronic stress breaks that feedback loop. Instead of shutting down, cortisol stays elevated, and the consequences ripple through the brain.
Persistently high cortisol weakens the prefrontal cortex, the very region you need for clear thinking and emotional control. At the same time, it increases activation in the amygdala, making you more emotionally reactive. The result is a brain that overresponds to perceived threats and struggles to calm itself down. Over time, this can manifest as hypervigilance, difficulty concentrating, impaired flexibility in thinking, and the kind of chronic worry that defines generalized anxiety disorder. Prolonged exposure to threatening environments, whether from violence, social pressure, or an unstable home, reinforces these changes.
Temperament as an Early Warning Sign
Some children show a pattern called behavioral inhibition: a consistent tendency to withdraw from unfamiliar people, objects, and situations. These are the toddlers who cling to a parent when a stranger enters the room, who stop playing or talking in new environments, and who take a long time to warm up. It’s more than ordinary shyness. It’s a measurable temperamental trait that shows up as early as 21 months of age.
Children who remain consistently inhibited through ages four, five, and seven have markedly higher rates of anxiety disorders. In one longitudinal study, eight out of 12 children who stayed inhibited across all follow-ups developed at least one anxiety disorder, compared to just one out of 10 who grew out of their initial inhibition. Inhibited children are also more likely to develop multiple anxiety disorders. In one study, 22% of behaviorally inhibited children had two or more anxiety disorders, compared to 0% of uninhibited children. Phobic disorders affected nearly 32% of inhibited children versus just 5% of their uninhibited peers.
Medical Conditions That Mimic or Trigger Anxiety
Sometimes anxiety symptoms have a physical origin. Conditions that cause pain, disability, or a sudden health crisis can trigger anxiety that persists long after the medical event. Arthritis, for example, has been shown to lead to new-onset generalized anxiety in older adults. A breast cancer diagnosis increases the risk of mental health disorders, partly because of the distress and intrusive thoughts that follow. Any illness perceived as traumatic can set off post-traumatic stress responses.
Thyroid disorders, cardiac arrhythmias, and other conditions that affect heart rate, breathing, or energy levels can also produce symptoms that feel identical to anxiety, including racing heart, restlessness, and difficulty sleeping. If anxiety symptoms appear suddenly without an obvious psychological trigger, a physical cause is worth investigating.
Substances That Can Cause or Worsen Anxiety
Anxiety symptoms commonly emerge during chronic use of or withdrawal from several substances. Alcohol, stimulants like cocaine and amphetamines, and even caffeine and diet pills can all induce anxiety. Withdrawal is a particularly common trigger. Stopping alcohol or short-acting sedatives can produce intense anxiety within days, while longer-acting medications like certain sedatives may cause withdrawal symptoms that take weeks to fully subside.
This creates a diagnostic challenge: is the anxiety a standalone disorder, or is it being driven by a substance? For shorter-acting substances like alcohol and cocaine, a period of abstinence can clarify things relatively quickly. For longer-acting drugs, it may take several weeks before the picture becomes clear.
Who Is Most at Risk
CDC data from 2022 shows that adults ages 18 to 29 report the highest rates of anxiety symptoms, with about 27% experiencing some level of anxiety. Rates decrease with age. Women report anxiety at higher rates than men, with 21% of women showing symptoms compared to lower rates in men.
Income and education matter too. Adults living below the federal poverty level had the highest anxiety rates at roughly 28%. Those without a high school diploma and those living in rural areas also reported elevated rates. Among racial and ethnic groups, White and Black adults had similar rates of anxiety symptoms (about 19% and 18%, respectively), both higher than Hispanic adults (16%) and Asian adults (12%).
What a Diagnosis Actually Looks Like
For generalized anxiety disorder, the most common type, the diagnostic bar requires excessive worry occurring more days than not for at least six months, with difficulty controlling the worry. Beyond that, you need at least three of these symptoms persisting over that same period: restlessness or feeling on edge, being easily fatigued, difficulty concentrating or your mind going blank, irritability, muscle tension, or sleep problems. The anxiety also needs to cause real disruption in your daily life, whether at work, in relationships, or in your ability to function, and it can’t be better explained by a medical condition or substance use.
Six months is the key threshold. Everyone worries. The distinction between normal worry and a disorder is duration, intensity, and whether it’s interfering with your ability to live your life the way you want to.