What causes common anxiety disorders?

Short answer: There’s no single cause. Anxiety disorders arise from a mix of biological vulnerabilities, brain and body differences, learned and cognitive patterns, and life experiences. How those factors combine varies by person and by the specific anxiety disorder.

Key contributors
- Genetics and family history: Anxiety runs in families. Twin and family studies show moderate heritability, meaning genes can increase vulnerability but don’t determine outcome on their own.
- Brain systems and neurochemistry: Overactivity of the brain’s fear network (especially the amygdala) and weaker regulation by the prefrontal cortex are common findings. Imbalances in neurotransmitters (serotonin, GABA, norepinephrine) and dysregulation of the stress hormone system (HPA axis) can promote persistent anxiety.
- Learning and conditioning: Fears can develop after traumatic events or become learned through association (classical conditioning) or by observing others (social learning). Avoidance behavior is reinforced because it reduces anxiety in the short term, which maintains the problem long-term.
- Cognitive patterns: Habitual tendencies to overestimate threat, catastrophize, worry excessively, or selectively attend to signs of danger sustain and amplify anxiety.
- Temperament and personality: High behavioral inhibition, neuroticism, or a tendency toward negative affect make anxiety more likely, especially when combined with stressors.
- Life events and stress: Childhood adversity, trauma, chronic stress (work, relationships, financial), and significant losses can trigger or worsen anxiety disorders.
- Medical conditions and substances: Thyroid disease, cardiac or respiratory problems, certain medications, withdrawal from alcohol or drugs, and stimulants can produce or worsen anxiety symptoms.
- Social and cultural factors: Social isolation, stigma, and stressful cultural or socioeconomic conditions can increase risk.

How causes differ by disorder (brief)
- Specific phobias: Often begin from a conditioning experience or strong learned fear.
- Social anxiety: Linked to temperamental shyness/behavioral inhibition and negative social experiences; strong worry about evaluation.
- Panic disorder: Involves heightened sensitivity to bodily sensations and a tendency to catastrophically interpret physical symptoms (interoceptive conditioning).
- Generalized anxiety disorder (GAD): Characterized by chronic worry tied to intolerance of uncertainty and cognitive/avoidance patterns.
- PTSD: Directly tied to exposure to a traumatic event that overwhelms normal coping.
(Obsessive–compulsive disorder and some other conditions have overlapping but partly distinct mechanisms and are classified separately.)

Bottom line
Anxiety disorders are usually multifactorial — genes and brain differences set the stage, and life experiences, learning, and thinking styles shape whether and how an anxiety disorder develops. If anxiety is interfering with daily life, effective treatments (psychotherapy, medications, lifestyle changes) are available; a mental health professional can assess causes and recommend treatment.