Obsessive-compulsive disorder is a serious mental health condition and one of the more difficult psychiatric problems to treat. OCD does cause anxiety but due to its distinctive signs and symptoms, etiology, and pathophysiology, it is not a sub-type of a broad classification of anxiety disorders. Because of the severe anxiety or dread associated with OCD symptoms, OCD was once thought to be an anxiety disorder. The American Psychiatric Association, however, withdrew OCD from the anxiety disorders categorization in 2013 and gave it its own classification. The adjustment was made to highlight differences in brain function and biochemistry between those with OCD and associated disorders and people with anxiety disorders. In people with OCD, parts of the brain that show abnormal results in tests and react when anxious emotions are provoked are different than in people with anxiety disorders like GAD. These distinctions are critical to comprehending and properly treating both illnesses.