The specific content of obsessions and compulsions varies between individuals. However, certain themes, or dimensions, are common, including those of cleaning (contamination obsessions and cleaning compulsions); symmetry (symmetry obsessions and repeating, ordering, and counting compulsions); forbidden or taboo thoughts (e.g., aggressive, sexual, or religious obsessions and related compulsions); and harm (e.g., fears of harm to oneself or others and checking compulsions). Some individuals also have difficulties discarding and accumulate (hoard) objects as a consequence of typical obsessions and compulsions, such as fears of harming others. These themes occur across different cultures, are rela— tively consistent over time in adults with the disorder, and may be associated with differ- ent neural substrates. Importantly, individuals often have symptoms in more than one dimension.
Individuals with 0CD experience a range of affective responses when confronted with situations that trigger obsessions and compulsions. For example, many individuals expe- rience marked anxiety that can include recurrent panic attacks. Others report strong feel- ings of disgust. While performing compulsions, some individuals report a distressing sense of "incompleteness” or uneasiness until things look, feel, or sound ”just right.”
It is common for individuals with the disorder to avoid people, places, and things that trigger obsessions and compulsions. For example, individuals with contamination con- cerns might avoid public situations (e.g., restaurants, public restrooms) to reduce ex- posure to feared contaminants; individuals with intrusive thoughts about causing harm might avoid social interactions.
The 12-month prevalence of 0CD in the United States is 1.2%, with a similar prevalence in— ternationally 0.1%—1.8%). Females are affected at a slightly higher rate than males in adulthood, although males are more commonly affected in childhood.
In the United States, the mean age at onset of OCD is 19.5 years, and 25% of cases start by age 14 years. Onset after age 35 years is unusual but does occur. Males have an earlier age at onset than females: nearly 25% of males have onset before age 10 years. The onset of symptoms is typically gradual; however, acute onset has also been reported.
If 0CD is untreated, the course is usually chronic, often with waxing and waning symp- toms. Some individuals have an episodic course, and a minority have a deteriorating course. Without treatment, remission rates in adults are low (e.g., 20% for those reevalu- ated 40 years later). Onset in childhood or adolescence can lead to a lifetime of OCD. How- ever, 40% of individuals with onset of 0CD in childhood or adolescence may experience remission by early adulthood. The course of 0CD is often complicated by the co—occurrence of other disorders (see section ”Comorbidity" for this disorder).
Compulsions are more easily diagnosed in children than obsessions are because com- pulsions are observable. However, most children have both obsessions and compulsions (as do most adults). The pattern of symptoms in adults can be stable over time, but it is more variable in children. Some differences in the content of obsessions and compulsions adult samples. These differences likely reﬂect content appropriate to different develop- mental stages (e.g., higher rates of sexual and religious obsessions in adolescents than in children; higher rates of harm obsessions [e.g., fears of catastrophic events, such as death or illness to self or loved ones] in children and adolescents than in adults).
Temperamental. Greater internalizing symptoms, higher negative emotionality, and behavioral inhibition in childhood are possible temperamental risk factors.
Environmental. Physical and sexual abuse in childhood and other stressful or traumatic events have been associated with an increased risk for developing OCD. Some children may develop the sudden onset of obsessive-compulsive symptoms, which has been asso- ciated with different environmental factors, including various infectious agents and a post-infectious autoimmune syndrome.