Generalized anxiety disorder

What is generalized anxiety disorder?

An abnormal and overwhelming sense of apprehension and fear often marked by physical signs (such as tension, sweating, and increased pulse rate), by doubt concerning the reality and nature of the threat, and by self-doubt about one's capacity to cope with it.

The numbers, as ADAA published them in 2020

These are the figures the Anxiety & Depression Association of America published when this issue was written. We checked their page as it stood in November 2020, and these were on it. They are not on it today — ADAA has revised them — so read these as a snapshot of 2020 rather than as current.

• Anxiety disorders are the most common mental illness in the U.S., affecting 40 million adults age 18 and older — 18.1% of the population — every year.
• Anxiety disorders are highly treatable, yet only 36.9% of those suffering receive treatment.
• People with an anxiety disorder are three to five times more likely to go to the doctor, and six times more likely to be hospitalized for psychiatric disorders, than those without.
• Anxiety disorders develop from a complex set of risk factors, including genetics, brain chemistry, personality, and life events.

One clarification, since these are reproduced as ADAA published them: the 18.1% is 18.1% of US adults, which is the group the 40 million is counted from. It is not 18.1% of the whole population.

Watch: Generalized anxiety disorder — causes, symptoms, and treatment (Osmosis, YouTube).

In their words

What Are Anxiety Disorders?

“Anxiety disorders are a set of related mental conditions that include: generalized anxiety disorder, panic disorder, obsessive-compulsive disorder (OCD), posttraumatic stress disorder (PTSD), social phobia, and simple phobias. Anxiety disorders are treated by a combination of psychiatric medications and psychotherapy.”

From PsychCentral.

Anxiety: A Poem on What Anxiety Really Is

“Anxiety is not all what it seems / It's not butterflies in your stomach / Or a rush of blood to your head / It's a thousand pounding drums in your chest… / Anxiety is desperately trying / To look strong when you're undeniably weak”

Read the poem (The Mighty)

What Does an Anxiety Disorder Feel Like?

“If 2.6 billion people were suffering from an illness, you'd think we'd all be more familiar with it… It represents the share of the world's population that will at some point experience an anxiety disorder.”

Read the article (TIME)

The chemistry behind anxiety

Rewritten September 2026. The original version of this section cited a page about a different condition, so every claim below was checked against NIH material one at a time. Claims that could not be supported were removed rather than re-pointed at a source that merely sounded right. This describes the body's stress response in general, which underlies anxiety rather than being specific to GAD.

The fast response

A stressor sets off a fast response through the sympathetic nervous system, which prompts the adrenal glands to release catecholamines. These narrow blood vessels and raise blood pressure, heart rate, and cardiac output, while widening the airways — the pounding chest and quick, shallow breathing that anxiety is felt as. The locus coeruleus, in the brain stem, is among the structures that trigger this reaction.

What the amygdala and hippocampus do

The amygdala, and particularly its central nucleus, processes the emotional side of stress and initiates fear responses. The hippocampus is critical to forming memories, and it also regulates the stress response by feeding back to the hypothalamus, damping the release of cortisol.

The slower response: the HPA axis

The slower arm is the hypothalamic-pituitary-adrenal (HPA) axis. The hypothalamus releases corticotropin-releasing hormone (CRH); CRH triggers the anterior pituitary to release adrenocorticotropic hormone (ACTH); and ACTH stimulates the adrenal cortex to secrete glucocorticoid hormones such as cortisol into the circulation.

Pain and freezing

The periaqueductal gray, in the midbrain, is a key structure in the modulation of pain and in the learning and carrying out of defensive behaviors. Stimulating part of it in animals produces freezing, running, and avoidance.

Books that portray anxiety

Celebrities who advocate

Shawn Mendes

“All pain is temporary… Sometimes it lasts two hours, sometimes it lasts a day and sometimes it lasts five minutes. The point of the song is that no matter how long that lasts, you can come out the other end stronger.”

Read the article (Teen Vogue) · On “In My Blood” (Genius)

Oprah Winfrey

“While Oprah still battles anxiety today, it's something that has affected her throughout her entire life… Her anxieties were rooted in the abuse she dealt with for years until she finally got professional help.”

Read the article (Beyond Anxiety and Depression)

Sources

1. Merriam-Webster — “Anxiety” (the definition)
2. Anxiety & Depression Association of America — Facts & statistics
3. Chu B et al., StatPearls (NIH National Library of Medicine) — Physiology, Stress Reaction (the fast response, the amygdala and hippocampus, and the HPA axis)
4. Fee C et al., StatPearls (NIH National Library of Medicine) — Neuroanatomy, Periaqueductal Gray (pain modulation and defensive behavior)

Sources were last checked September 2026. Every source links to the exact document cited, never a homepage.