Researchers have compared obsessive-compulsive disorder (OCD) with obsessive-compulsive personality disorder (OCPD) in what may be the first such comparison of the two disorders that share certain characteristics. The latter is the most common personality disorder in the U.S. population according to the National Epidemiologic Survey on Alcohol and Related Conditions.
The researchers found that while both OCD and OCPD are impairing disorders marked by compulsive behaviors, they can be differentiated by the presence of obsessions in those with OCD and by the capacity to delay reward in those with OCPD.
The study was headed by Anthony Pinto, Ph.D., an assistant professor of clinical psychology at Columbia University. The senior researcher was H. Blair Simpson, M.D., Ph.D., a professor of psychiatry at Columbia. The results were published online November 6, 2013, in Biological Psychiatry.
Past research has suggested that OCD and OCPD are genetically related. OCPD can be found in one-fourth to one-third of individuals with OCD and an even greater percentage of the first-degree relatives of individuals with OCD. But even though OCD and OCPD are genetic relatives and share similar names, Pinto, Simpson, and their colleagues decided to conduct a study to find out how similar they actually are.
The study included 100 subjects—25 with DSM-IV-diagnosed OCD alone, 25 with DSM-IV-diagnosed OCPD alone, 25 with both DSM-IV-diagnosed OCD and OCPD, and 25 healthy controls. There were no significant group differences in age, gender, marital status, race, number of years of education, IQ, household income, or employment status.
The researchers compared symptoms, psychosocial functioning, and one dimension of self-control—the ability to delay reward.
Both OCD subjects and OCPD subjects were found to be impaired in psychosocial functioning and quality of life compared with the healthy control subjects.
Subjects with OCD—with or without OCPD—displayed one or more of the following symptoms—taboo thoughts, contamination/cleaning, doubt/checking, symmetry/ordering, and hoarding.
As for individuals with OCPD but not OCD, none reported intrusive, distressing thoughts or images (obsessions), but they did report ritualized/methodical behaviors, such as list making, organizing belongings, or repeatedly checking or editing written work. When compared on obsessive-compulsive behaviors, those with OCD were more likely to endorse washing and obsessing, while those with OCPD were more likely to endorse ordering and hoarding behaviors.
When it came to ability to delay reward, OCPD subjects were significantly better at doing so than OCD subjects or healthy controls. Furthermore, the exceptional ability of individuals with OCPD to delay reward was found to be linked to two other traits that are core components of OCPD—perfectionism and rigidity.
Thus, “OCD and OCPD are not the same thing despite the similarity in names,” Simpson told Psychiatric News. “Specifically, ritualized behaviors occurred in both disorders, but only those with OCD had obsessions. In addition, people with OCPD had a greater capacity to delay reward as measured by our task than people with OCD or healthy controls.”
The findings also have clinical implications, Simpson pointed out.
For example, there are no evidence-based treatments for individuals with OCPD. But given that a preference for delayed reward has been linked by other researchers with heightened activation of the dorsolateral prefrontal cortex, “our findings suggest potential brain-behavior relationships in OCPD, providing support for future imaging studies, and the development of novel pharmacologic and psychosocial strategies to modulate excessive self-control.”
“Our data also suggest that the capacity to delay reward may lead to problems either if diminished (as in substance use disorders) or excessive (as in anorexia nervosa and now OCPD). Such a dimensional perspective may lead to new treatment interventions that cross traditional diagnostic boundaries.”
The research was funded by the National Institute of Mental Health and the New York State Office of Mental Hygiene. ■