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Section 13
Obsessive-Compulsive Disorder Part Two

Question 13 | Test | Table of Contents

Axis I comorbidity
A further complication in defining the external boundaries of OCD, lies in the extensive comorbidity associated with the condition. Indeed, it is more the rule than the exception to find at least one comorbid psychiatric disorder in individuals with OCD. Depression is particularly common in OCD subjects.  One of the difficulties here is that of trying to determine cause and effect, and to ascertain which ‘cases’ of OCD might be secondary to another disorder. An extreme approach is that adopted by the CATEGO algorithm, linked to the PSE, in that the symptoms of depression effectively ‘trump’ those of OCD, making it almost impossible to diagnose anyone as having OCD. Clearly, more flexibility is required in this regard, but clinicians will be aware of the difficulties inherent in teasing apart depressive and OCD symptoms, and will have seen patients whose OCD symptoms only come to the fore when they are depressed. Conversely, of course, OCD, with its associated disability and negative impact of family, leisure, and occupational functioning, provides fertile ground for the evolution of depression.

In terms of eating disorders, Rubenstein, using the SCID diagnostic interview, found that in 62 patients with OCD, the lifetime prevalence of anorexia nervosa or bulimia nervosa was 12.9%, with an additional 17.7% of subjects having had a subthreshold eating disorder at some time in their lives; these rates are far higher than those reported for the general population. Also of interest is that males with OCD were as likely as their females counterparts to have suffered from an eating disorder, in stark contrast to the uniform female excess of eating disorders in general population samples.

The high comorbid occurrence of OCD and anorexia/bulimia nervosa is worth considering further. Indeed, many of the features of these eating disorders could be construed as OCD symptoms. For example, the obsessional thinking about fatness and the often ritualised eating habits, calorie-counting and exercise, as well as the anxiety associated with the ‘fear of fatness’, would all be compatible with diagnoses of OCD or BDD, were it not for specific exclusion criteria in the DSM. But, it does beg the question, touched on above, of the relationship of these disorders to each other.

Having reviewed the internal and external boundaries of OCD, we now outline a putative model for subtyping OCD, on the basis of gender and age at onset. As a prelude, we examine these parameters in OCD, and also explore determinants of good and poor outcome of the disorder.

Obsessive–compulsive disorder in childhood
It is well recognised that many children, as part of normal development, go through a stage characterized by obsessions and compulsions. These often have a somewhat ‘magical’ or ‘superstitious’ quality, such as having to step over every crack in the pavement or touch every lamp post on the walk to school.  However, the symptoms rarely cause much distress, nor impair functioning, and usually children ‘grow out of’ them. In a minority of such children, the child or their parents become sufficiently concerned to seek professional help, and usually only brief intervention is required. However, in a small proportion of cases, the symptoms persist and become entrenched, such that they can be considered the beginning of OCD. Boys tend to be affected more often than girls.

Obsessive–compulsive disorder and gender
Gender effects have increasingly been seen as providing potential clues to the pathogenesis of a number of psychiatric disorders, and in this context a consideration of gender effects in OCD is appropriate. However, the field is once more bedeviled by methodological problems, not least of which is case ascertainment. Thus, while in treated samples of patients with OCD, the male : female ratio is usually around unity, in epidemiological samples, females tend to be more commonly represented than males.

For example, Bebbington, in reviewing epidemiological studies of OCD, concluded that the male : female ratio is ‘roughly 1:1.5’. This discrepancy between treated and epidemiological samples is presumably a reflection, in part at least, of differences between men and women in terms of help-seeking behaviour, the degree to which the impairment associated with OCD can be tolerated and accommodated by families in male and female family members and the degree of occupational impairment and gender differences in occupational expectations.

The extent to which these factors can explain the difference in gender ratio between treated and untreated samples, is difficult to assess. What is also probable is that males are more likely to get into treatment because they are relatively more prone to a severe form of OCD (although formal attempts to assess gender differences in severity of illness is inevitably complicated by the very fact that those who are most likely to be included in any such study, are those who have sought treatment). What is clear from both epidemiological and treated samples is that the symptoms of OCD tend to be somewhat different between the sexes. Thus, males tend to have more problems with ruminations, and females are more likely than males to be afflicted with cleanliness and checking rituals. It might be that this plays some part in determining the impact of the illness on the individuals’ daily functioning. Certainly, ruminations without rituals are notoriously difficult to treat.

Another issue of potential importance in determining the cause of gender differences in OCD, is age at onset differences between males and females with the disorder. In general, males tend to have a somewhat earlier onset than their female counterparts, and males predominate in cases of childhood OCD, as detailed above. In a study specifically of gender differences in OCD, Castle et al. assessed gender differences in a sample of 219 OCD patients, who had been referred to a tertiary treatment centre in London, UK. The male : female ratio was 1:1.35, and the mean age at onset was 22 years for males and 26 years for females (p = 0.003). Duration of illness prior to seeking help was 11.5 years for males and 9.2 years for females. Males exceeded females among those individuals whose onset of illness occurred before the age of 16 years, whereafter females predominated. This finding is compatible with the notion that there might be relatively discrete subtypes of OCD, to which males and females are differentially prone.

Long-term outcome
A further consideration in any attempt to subtype OCD, is what determines good and poor long-term outcome of the disorder. Although there are numerous studies of the treated outcome of OCD, these have mostly been conducted to determine the longterm efficacy of particular treatment interventions, and thus do not reflect the natural history of OCD. For that, we require studies which have determined the longitudinal  course of unselected samples of OCD patients over an extended period. Regrettably (for the epidemiologist, at least), such studies are very difficult to do, and almost always have some methodological flaws.

However, the recent long-term follow-up study of Skoog and Skoog is most enlightening. These authors personally followed up 122 of 251 OCD patients who had originally been admitted to hospital in Sweden between 1947 and 1953, over a mean period of 47 years from illness onset. For a further 22 patients, necessary information was obtained from informants and medical records, resulting in an overall 82% follow up of surviving patients. Subjects had received an array of different interventions, including psychosurgery (6 patients) and clomipramine (17 patients). Improvement was observed in 83% of subjects, with complete recovery in 20% and subclinical symptoms persisting in a further 28%. However, 48% of patients had had OCD symptoms for over 30 years. Associations with poor outcome included early illness onset, low baseline social functioning and having both obsessive and compulsive symptoms. This adds further to the notion that early onset of illness might be a characteristic of a particularly pernicious subtype of OCD. We now outline an integrative and interpretative model for subtyping of OCD.

A neurodevelopmental subtype of obsessive–compulsive disorder?
The parameters outlined above, of the impact of gender and age-at-onset, on the long-term outcome of OCD, reinforce the notion that some patients with OCD might have a neurodevelopmental disorder, in the sense that something goes awry with brain development at an early age (perhaps prenatally or perinatally). Of course, such an hypothesis is currently very much speculative, but a number of strands of evidence can be brought together to support it.

One of the parameters underpinning this hypothesis is that OCD has been shown, despite its historical ‘neurotic’ label, to be a disorder associated with brain dysfunction. The compelling evidence for serotonergic dysregulation in OCD, has been alluded to above. With the advent of modern neuroimaging techniques, further light is being shed on brain structural and functional abnormalities in OCD. In a recent review, Saxena et al. noted that structural and brain imaging studies of OCD patients generally suggest abnormalities in orbitofrontal and anterior cingulated cortex, and in parts of thalamus and striatum. These structures have historically been implicated as linked in a functional neuranatomic circuit. Functional neuroimaging studies have shown evidence of hypometabolism in the orbitofrontal cortex of OCD patients, and have found that this correlates with the severity of symptoms and normalises with treatment.

Of particular current interest is that the immune sequelae of infection by group A beta-haemolytic streptococcus can result in a variety of neuropsychiatric conditions in children, including tic disorder and OCD. These so-called paediatric autoimmune neuropsychiatric disorders associated with streptococcal infections (PANDAS) are presumed to be consequent upon the formation of antibodies which cross-react with neural tissue. Again, this underlines the importance of brain insult in the pathogenesis of at least some cases of OCD. A further example of brain insult associated with obsessive–compulsive symptomatology is the occurrence of such symptoms as a sequel to encephalitis lethargica. Neurodevelopmental disorders are usually characterized by an early onset, severe symptoms and a poor longitudinal course; these disorders also tend to affect males more than females. As detailed above, those individuals whose onset of OCD occurs in childhood or early adulthood do indeed tend to be male. They also tend to have severe symptoms, significant disability and a poor outcome, with a relatively poor response to treatment. Furthermore, such individuals tend to have certain associated features which are also compatible with the notion that they have a disorder of neurodevelopment. These include an excess of ‘soft’ neurological signs, an excess of motor tics and poor performance on neuropsychological tests of visuospatial functioning. These strands have been brought together in a proposal that a neurodevelopmental form of OCD can be delineated, distinct from a putative ‘primary’ type, characterized by a later onset, a milder/episodic course and a favourable response to serotonergic agents; females are relatively more prone to this latter form of the illness. This subtyping has strong similarities with the models proposed for schizophrenia. Of course, much more research is required before accepting this proposed typology, and the mediating effect of gender and associated confounding factors must also be considered.

We have reviewed here some of the more controversial aspects of the epidemiology of obsessive–compulsive disorder. What is clear is that OCD is not uncommon, though the internal and external boundaries of the disorder are difficult to delineate definitively. The notion of an ‘OCD-spectrum’ of disorders has heuristic appeal, and can also inform aetiological models as well as therapeutic interventions. Of particular theoretical interest is the notion that some patients with OCD might have a neurodevelopmental disorder.
- Castle, David J.; Groves, Aaron. Australian and New Zealand Journal of Psychiatry 2000.

Personal Reflection Exercise #6
The preceding section contained information about the internal and external boundaries of obsessive-compulsive disorder. Write three case study examples regarding how you might use the content of this section in your practice.

Obsessive-Compulsive Disorder

Brock, H., & Hany, M. (2023). Obsessive-Compulsive Disorder. In StatPearls. StatPearls Publishing.

Peer-Reviewed Journal Article References:
Benito, K. G., Machan, J., Freeman, J. B., Garcia, A. M., Walther, M., Frank, H., Wellen, B., Stewart, E., Edmunds, J., Kemp, J., Sapyta, J., & Franklin, M. (2018). Measuring fear change within exposures: Functionally-defined habituation predicts outcome in three randomized controlled trials for pediatric OCD. Journal of Consulting and Clinical Psychology, 86(7), 615–630.

Conrad, R., Bousleiman, S., Isberg, R., Hauptman, A., & Cardeli, E. (2020). Uncontrolled experiments: Treatment of contamination OCD during a pandemic. Psychological Trauma: Theory, Research, Practice, and Policy, 12(S1), S67–S68.

Wahl, K., van den Hout, M., Heinzel, C. V., Kollárik, M., Meyer, A., Benoy, C., Berberich, G., Domschke, K., Gloster, A., Gradwohl, G., Hofecker, M., Jähne, A., Koch, S., Külz, A. K., Moggi, F., Poppe, C., Riedel, A., Rufer, M., Stierle, C., . . . Lieb, R. (2021). Rumination about obsessive symptoms and mood maintains obsessive-compulsive symptoms and depressed mood: An experimental study. Journal of Abnormal Psychology, 130(5), 435–442. s

How do the symptoms of OCD tend to be somewhat different between the sexes? To select and enter your answer go to Test

Section 14
Table of Contents