Individuals with OCD vary in the degree of insight they have about the accuracy of the beliefs that underlie their obsessive-compulsive symptoms. Many individuals have good or fair insight (e.g., the individual believes that the house definitely will not, probably will not, or may or may not burn down if the stove is not checked 30 times). Some have poor insight (e.g., the individual believes that the house will probably burn down if the stove is not checked 30 times), and a few (4% or less) have absent insight/delusional beliefs (e.g., the in- dividual is convinced that the house will burn down if the stove is not checked 30 times).
Insight can vary within an individual over the course of the illness. Poorer insight has been linked to worse long-term outcome.
Up to 30% of individuals with OCD have a lifetime tic disorder. This is most common in males with onset of 0CD in childhood. These individuals tend to differ from those with- out a history of tic disorders in the themes of their 0CD symptoms, comorbidity, course, and pattern of familial transmission.
The characteristic symptoms of 0CD are the presence of obsessions and compulsions (Cri- terion A). Obsessions are repetitive and persistent thoughts (e.g., of contamination), images (e.g., of violent or horrific scenes), or urges (e.g., to stab someone). Importantly, obsessions are not pleasurable or experienced as voluntary: they are intrusive and unwanted and cause marked distress or anxiety in most individuals. The individual attempts to ignore or suppress these obsessions (e.g., avoiding triggers or using thought suppression) or to neu- tralize them with another thought or action (e.g., performing a compulsion). Compulsions (or rituals) are repetitive behaviors (e.g., washing, checking) or mental acts (e.g., counting, repeating words silently) that the individual feels driven to perform in response to an obsession or according to rules that must be applied rigidly. Most individuals with OCD have both obsessions and compulsions. Compulsions are typically performed in response to an obsession (e.g., thoughts of contamination leading to washing rituals or that some- thing is incorrect leading to repeating rituals until it feels "just right”). The aim is to reduce the distress triggered by obsessions or to prevent a feared event (e.g., becoming ill). How- ever, these compulsions either are not connected in a realistic way to the feared event (e.g., arranging items symmetrically to prevent harm to a loved one) or are clearly excessive (e.g., showering for hours each day). Compulsions are not done for pleasure, although some individuals experience relief from anxiety or distress.
Criterion B emphasizes that obsessions and compulsions must be time-consuming (e.g., more than 1 hour per day) or cause clinically significant distress or impairment to warrant a diagnosis of OCD. This criterion helps to distinguish the disorder from the occasional in— trusive thoughts or repetitive behaviors that are common in the general population (e.g., double-checking that a door is locked). The frequency and severity of obsessions and com- pulsions vary across individuals with 0CD (e.g., some have mild to moderate symptoms, spending 1—3 hours per day obsessing or doing compulsions, whereas others have nearly constant intrusive thoughts or compulsions that can be incapacitating).