Anxiety: A Very Short Introduction - Daniel Freeman, Jason Freeman 2012

How common is OCD?
Obsessive-compulsive disorder

Intrusive thoughts, as we’ve seen, are normal, with around 80% of people experiencing them from time to time. It’s been estimated that the average person has around 4,000 thoughts each day, most of them lasting about five seconds. Approximately 13% of these thoughts (i.e. around 500) appear in our minds spontaneously.

Roughly 2—3% of people develop OCD at some point in their life. The recent US National Comorbidity Survey Replication (NCSR) estimated that 1.2% of the people questioned had suffered from OCD over the past twelve months, with the lifetime figure put at 2.3%. The most common forms of the illness were checking, hoarding, and ordering. On average, obsessions took up 5.9 hours a day, and compulsions 4.6 hours. Given the amount of time consumed by OCD, it’s hardly surprising that almost two-thirds of those who’d experienced the illness in the previous year reported that it had severely interfered with their day-to-day life.

As we’ve seen, many anxiety disorders seem to be much more prevalent among women than men. The picture is less clear in the case of OCD; the NCSR reported that women were at significantly greater risk than men, yet other studies have found no gender differences.

OCD can develop at any age, but most usually occurs during late adolescence or early adulthood (in the NCSR, average age for onset was 19.5 years).