OCD

Epidemiology

Prevalence

Previously OCD was thought to be a rare, untreatable disorder. Yet, it can be a chronic debilitating disease. Although obsessive-compulsive disorder (OCD) is among the most common of all psychiatric disorders, the diagnosis is frequently overlooked unless specific screening questions are asked by the treating physician. The obsessive thinking and compulsive behaviours that primarily characterise OCD can be found in other obsessive-compulsive spectrum disorders as well. These disorders affect a sizeable percentage of the U.S. population and have thus become an increasing public health problem (Hollander et al., 1996b).

OCD has a major impact on quality of life and is more common than previously believed - affecting 2% to 3% of the world’s population (Hollander, 1997). It is the fourth most common psychiatric illness in the USA (Karno et al., 1988) and is the tenth highest cause of disability in the world (Murray and Lopez, 1996).

Only during the last decade, the prevalence of OCD symptoms in the general population has been found to be remarkably high. Previously the most quoted figure was below 1%. However, since the mid-1980’s, studies carried out in North America found the prevalence of OCD in the general population to be greater than 2% (Karno et al., 1988). OCD lifetime prevalence is approximately 2% in the United States, Canada, and Puerto Rico. These findings confirm the figures for Europe and New Zealand. In Korea, OCD prevalence is 1.9%, and in Taiwan, 0.7%. Therefore, with the exception of Taiwan, where the prevalence of all psychiatric disorders is relatively low, OCD lifetime prevalence world-wide is approximately 2%. The estimated total number of patients who suffer from the disorder world-wide appears to be at least 50 million. This finding equals OCD with schizophrenia in terms of prevalence.

Across all the researched sites, it was found that persons with OCD were likely to have major depression or some other anxiety disorder as a co-morbid condition. This may possibly be due to the relationship of both these disorders to serotonin dysfunction in the brain. There seems to be some form of correlation between the two diagnoses. Abnormal dexamethasone suppression tests have been reported in up to 38% of primary OCD patients (Insel et al., 1982; Cottraux et al., 1984.