Which of the following is NOT a common category of anxiety disorders?

Obsessive-compulsive disorder is classified as an anxiety disorder, but it is important to recognize that it was reclassified in the DSM-5 (Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition) under its own chapter called "Obsessive-Compulsive and Related Disorders." This change reflects a growing understanding that, while it shares some features with anxiety disorders, OCD has distinct characteristics that warrant a separate classification.

The other disorders listed—separation anxiety, panic disorder, and social anxiety disorder—are all commonly recognized categories within the anxiety disorders umbrella in the DSM-5. Separation anxiety involves excessive anxiety concerning separation from home or attachment figures; panic disorder involves recurrent unexpected panic attacks and persistent concern about having additional attacks; and social anxiety disorder is characterized by intense fear or anxiety in social situations due to concerns about being judged negatively by others. Understanding the organization of these disorders can help clarify the distinctions among them, especially in regard to diagnosis and treatment.