A Primer on Obsessive Compulsive Disorder (OCD)


Repetitive, intrusive, unwanted and high anxiety-triggering thoughts or images are at the root of OCD. These mental experiences are coupled with subsequent behaviors that are aimed at reducing the intensity of anxiety. So thoughts about being contaminated can quickly trigger the urge to wash. OCD is debilitating – it is time consuming and “mind” consuming – it requires substantial effort to avoid or manage the anxiety. People with OCD can appear distracted, distant and exhausted. The costs can add up and be staggering – relationship strain and break up, job loss, poor academic performance, and loneliness and isolation.

The nature of “obsessive” thoughts can vary, but they can group around some particular themes: aggression, contamination, sexual thoughts, intense fears about losing items, religious concerns, symmetry or exactness, or needing to know or remember things exactly. These thoughts are accompanied by rapid increases in anxiety and/or disgust and a general intense discomfort.

The urges to fix, neutralize, eliminate or plan for consequences of the obsessive thoughts lead to carrying out a dizzying variety of coping behaviors. Over time, these coping behaviors can become compulsive.  A coping strategy that may have been comforting and helpful at some point transitions into a compulsion when it becomes highly involved, time consuming, exhausting and repetitive. Compulsions can be overtly behavioral – like excessive handwashing or showering, asking for reassurance multiple times, or excessive checking.  Compulsions can also be primarily internal behaviors like mental scanning, remembering, replaying an experience over and over, imagining a positive image to neutralize a negative image. At first these behaviors provide relief. Over time, they become a cause or exacerbator of anxiety if they are not performed. Thus the very responses that were helpful eventually become a central cause of disruption and anxiety in the long run.

Treatment options for OCD can be complex. The foundation of the treatment approach is exposure and response prevention (ERP), a behavior-focused strategy that helps individuals learn how to cope with intense anxiety without resorting to compulsive behaviors.  ERP sounds conceptually straight forward, but can be quite challenging to implement. You should look for treatment providers that are very experienced in using it.


The lifetime prevalence of OCD is approximately 2-3% (Ruscio, Stein et al, 2010; Karno, Golding et al, 1988); this estimate means that over the course of the lifetimes of a general group of adult individuals, 2-3% of them will develop OCD at some point. The prevalence of OCD is approximately 1% of the general population, meaning that if we took a survey of a random sample of individuals, 1% of them would currently have OCD (Ruscio et al, 2010; Adam, Meinlschmidt et al, 2012). Keep in mind that mental experiences like obsessions and intrusions and compulsivity occur along a continuum. Adam and colleagues (2010) report that 14% of their large sample (so 564 out of 4181 participants) reported at least one obsessive-compulsive symptom in the last 12 months and 4% reported “subthreshold” OCD.

Men and women have similar rates of OCD. The course of OCD is variable, the average age of onset is 19. However, the age of onset varies based on gender. Men tend to have a more early onset of symptoms, with 25% reporting beginning of symptoms before age 10 and very few women reporting onset of symptoms before 10 years old (Ruscio et al, 2010).


Fully 75% of individuals with OCD also have a diagnosable comorbid anxiety disorder, 63% have a comorbid mood disorder, 55% had previous impulse control disorder, 38% had a comorbid substance use disorder (Ruscio et al, 2010). The most common anxiety disorder in the Ruscio et al study was social anxiety disorder (44%), closely followed by specific phobia (43%), separation anxiety disorder (37%), panic disorder (20%) and generalized anxiety disorder (8%). The majority of the time, these respondents indicated that the anxiety disorder preceded OCD (60-90% of the time).  Approximately 19% of respondents with OCD also had PTSD.

For mood disorders, major depressive disorder was the most common mood disorder, with 41% of OCD patients having the diagnosis, 13% had dysthymic disorder and 23% had bipolar disorder. What came first OCD or a mood disorder? The answer is - it varies. For 46% of the OCD patients from the Ruscio et al study, OCD came first. But for 40%, the depression came first, then the OCD. Fifteen percent reported the mood disorder and OCD starting in the same year.


In the sample reported by Ruscio et al (2010), treatment seeking varied by severity of symptoms. 60% of patients with severe OCD reported getting psychiatric and/or psychological treatment for OCD and 20% of these patients said they had been hospitalized due to their OCD, at some point in their lives. But for those with moderate OCD, only 13% were getting outpatient treatment.


Assessment of OCD can be divided into two categories, structured interviews and self report measures.

Structured Interviews

Yale Brown Obsessive Compulsive Scale (YBOCS), versions 1 and 2

The Yale-Brown Obsessive Compulsive Scale (YBOCS) is the most common measure used to assess the severity of symptoms of OCD. First published in 1989 (Goodman, Price et al,1989), it involves a lengthy checklist of 58 specific obsessions and compulsions, followed by a 10-item form assessing the severity of symptoms. Each item is scored 0-4 and it yields a score ranging from 0-40.

In 2006, the YBOCS 2 was published. It was a substantial revision and update of the YBOCS and overhauled the checklist portion and added a section on avoidance. It also revamped the items and scoring of the 10-item severity portion of the interview. The YBOCS 2 still has 10 items but is scored on a scale of 0-5, thus scores can range from 0-50.  The YBOCS 2 does not have a disorder severity cut score index like the YBOCS, but generally speaking, scores above 30 are considered severe to extreme.

The Dimensional Obsessive Compulsive Scale (DOCS)

The DOCS was published recently (Abramowitz et al., 2009) and is considerably different from the YBOCS. At the time, one of the short-comings of the YBOCS was its extensive checklist of obsessions and compulsions without integrating these items into larger conceptual constructs. It also separated obsessions from compulsions, making it more difficult to see connections between the two.  

The DOCS involves four broad categories, or concerns:

Concerns about germs

Concerns about being responsible for harm, injury or bad luck

Having unacceptable thoughts

Concerns about symmetry, completeness and the need for things to be just right

The DOCS has five questions about each concern, with each question scored from 0-4, thus the highest total score on the measure would be 80. For individuals with OCD, mean scores range between 25-32 with standard deviations ranging from 15-20 (Eilertson, Hansen et al, 2017). Non-OCD college student samples have means ranging from 10-13 and standard deviations ranging from 9-10. Abramowitz and colleagues (2010) reported in a large validation study that a DOCS score of 18 is a useful cut score for identifying someone with clinically significant OCD symptoms.

Self-report assessments

There are a number of questionnaires that researchers have developed and used to measure severity and extent of OCD symptoms. The Obsessive Compulsive Inventory - Revised (OCI-R: Foa, Huppert et al 2002) is an 18 item questionnaire that measures a range of obsessions and compulsions. It has six scales (or categories): washing, checking, ordering, obsessing, hoarding and neutralizing. Each item can generate of score ranging from 0 to 4, with the total score of the questionnaire being 72. However, the OCI-R has a cut score of 14 for “likely OCD”, with OCD patients scoring a mean of 28 +/- std deviation 13 (Abramowitz & Deacon, 2006). Surprisingly, the OCI-R does not correlate highly with the YBOCS; in a validation study, total OCI-R scores had a .41 correlation with YBOCS scores (Abramowitz & Deacon, 2006). This could be because the OCI-R measures the degree to which the respondent was  distressed or bothered by the specific items on the measure (eg “I check things more often than necessary”) whereas the YBOCS measures distress but also other factors like time, resistance, control and interference in daily life.