OCD is an anxiety disorder in which patients experience recurrent obsessions and compulsions that cause significant distress and occupy a significant portion of their lives.

Epidemiology

The lifetime prevalence of OCD is 2% to 3%. Typical onset of the disorder is between the late teens and early 2Us, but one third of patients show symptoms of OCD before age 15.

Etiology

Behavioral models of OCD claim that obsessions and compulsions are produced and sustained through classic and operant conditioning. Interestingly, OCD is seen more frequently after brain injury or disease (e.g., head trauma, seizure disorders, Huntington’s disease), and twin studies show that monozygotic twins ‘have a higher concordance rate than dizygotic twins; these findings support a biologic basis for the disorder. The neurotransmitter serotonin has been implicated as a mediator in obsessive thinking and compulsive behaviors.

Clinical Manifestations

History and Mental Status Examination
Patients with OCD experience obsessions and compulsions. Obsessions are recurrent intrusive ideas, thoughts, or images that cause significant anxiety and distress; compulsions are repetitive purposeful physical or mental actions that are generally performed in response to obsessions. The compulsive “rituals” are meant to neutralize the obsessions, diminish anxiety, or somehow magically prevent a dreaded event or situation.

Differential Diagnosis
It is important to distinguish the obsessional thinking of OCD from the delusional thinking of schizophrenia or other psychotic disorders. Obsessions are usually unwanted, resisted, and recognized by patients as coming from their own thoughts, whereas delusions are generally regarded as distinct from patients’ thoughts and are typically not resisted. For example, patients with depression often experience obsessive ruminations that can be distinguished from obsessions because they are transient, not considered unwanted, and not resisted.

Management

Clomipramine and SSRIs have been shown to be quite effective in treating OCD. Although poorly studied, the behavioural techniques of systematic desensitization, flooding, and response prevention have been used successfully to treat compulsive rituals. For example, someone who fears contamination from an object will hold the object repeatedly in therapy while simultaneously being prevented from carrying out the ritual associated with the dreaded object.