Anxiety disorders are considered the #1 most common mental illness worldwide. They affect more people than depression, bipolar disorder, or schizophrenia combined.

Why Anxiety Tops the List

According to the World Health Organization (WHO) and U.S. data, over 300 million people globally live with an anxiety disorder. In the U.S. alone, nearly 20% of adults—about 1 in 5—experience anxiety each year. Common types include generalized anxiety disorder (GAD), social anxiety, panic disorder, and phobias.

Anxiety becomes a disorder when worry is excessive, persistent, and interferes with daily life. It’s more than normal stress—it can cause physical symptoms like rapid heartbeat, fatigue, and trouble sleeping.

While depression is also extremely common—and often co-occurs with anxiety—anxiety disorders rank #1 in prevalence. They often start in adolescence or early adulthood and can last for years if untreated.

The good news? Anxiety is highly treatable. Therapy (especially cognitive behavioral therapy), medication, lifestyle changes, and support can significantly reduce symptoms.

So, when asking “What is the #1 mental illness?” the answer is clear: anxiety disorders hold that title due to their widespread impact across ages, cultures, and regions. Early recognition and care make a major difference in quality of life.