Which of the following is NOT classified as an anxiety disorder?

Rett Syndrome is classified as a neurodevelopmental disorder rather than an anxiety disorder. It typically affects girls and is characterized by a period of normal development followed by a loss of purposeful hand skills and social engagement skills, along with cognitive impairment and other neurological issues.

On the other hand, Generalized Anxiety Disorder, Panic Disorder, and Posttraumatic Stress Disorder are all recognized categories of anxiety disorders. Generalized Anxiety Disorder involves excessive worry about various topics, Panic Disorder is marked by recurrent panic attacks, and Posttraumatic Stress Disorder occurs following exposure to a traumatic event, leading to severe anxiety symptoms. Understanding the differences among these classifications is crucial for proper diagnosis and treatment in the context of mental health.