As many as two thirds of patients with what disorder also meet the diagnostic criteria for obsessive-compulsive disorder?

Choice A reason: There is a high rate of comorbidity between Tourette disorder and obsessive-compulsive disorder (OCD). Clinical studies indicate that up to 60% to 90% of individuals with Tourette disorder also exhibit OCD symptoms, and approximately two thirds meet the full diagnostic criteria for OCD. Both disorders are thought to involve common neurobiological pathways in the cortico-striato-thalamo-cortical circuits. Choice B reason: While generalized anxiety disorder (GAD) and OCD are both characterized by anxiety, the comorbidity rate is not as high as two thirds. GAD involves pervasive worry about various life domains, whereas OCD is defined by specific obsessions and compulsions. These are distinct diagnostic entities with different underlying cognitive and behavioral structures. Choice C reason: Body dysmorphic disorder (BDD) is currently classified in the DSM-5 under "Obsessive-Compulsive and Related Disorders" due to its similarities with OCD. While comorbidity is significant, the "two thirds" figure is most traditionally and robustly associated with the specific link between Tourette disorder and the development of obsessive-compulsive symptoms. Choice D reason: Panic disorder and OCD may co-occur as part of a broader anxiety profile, but they do not share the high-frequency diagnostic overlap seen with Tourette disorder. The prevalence of OCD in patients with panic disorder is much lower than the significant majority reported in patients with chronic tic disorders.