Animal behavior as a conceptual framework for the study of obsessive-compulsive disorder (OCD).

Research on affective disorders may benefit from the methodology of studying animal behavior, in which tools are available for qualitatively and quantitatively measuring and assessing behavior with as much sophistication and attention to detail as in the analysis of the brain. To illustrate this, we first briefly review the characteristics of obsessive-compulsive disorder (OCD), and then demonstrate how the quinpirole rat model is used as a conceptual model in studying human OCD patients. Like the rat model, the study of OCD in humans is based on video-telemetry, whereby observable, measurable, and relatively objective characteristics of OCD behavior may be extracted. In this process, OCD rituals are defined in terms of the space in which they are executed and the movements (acts) that are performed at each location or object in this space. Accordingly, OCD behavior is conceived of as comprising three hierarchical components: (i) rituals (as defined by the patients); (ii) visits to objects/locations in the environment at which the patient stops during the ritual; and (iii) acts performed at each object/location during visits. Scoring these structural components (behavioral units) is conveniently possible with readily available tools for behavioral description and analysis, providing quantitative and qualitative measures of the OCD hallmarks of repetition and addition, as well as the reduced functionality in OCD behavior. Altogether, the concept that was developed in the context of an animal model provides a useful tool that may facilitate OCD diagnosis, assessment and treatment, and may be similarly applied for other psychiatric disorders.

Manifestation of incompleteness in obsessive-compulsive disorder (OCD) as reduced functionality and extended activity beyond task completion.

BACKGROUND: This study focused on hypotheses regarding the source of incompleteness in obsessive-compulsive disorder (OCD). For this, we had to document the behavioral manifestation of incompleteness in compulsive rituals, predicting that an exaggerated focus on acts that are appropriate for the task will support the hypothesis on heightened responsibility/perfectionism. In contrast, activity past the expected terminal act for the motor task would support the "stop signal deficiency" hypothesis. METHODOLOGY AND PRINCIPAL FINDINGS: We employed video-telemetry to analyze 39 motor OCD rituals and compared each with a similar task performed by a non-OCD individual, in order to objectively and explicitly determine the functional end of the activity. We found that 75% of OCD rituals comprised a "tail," which is a section that follows the functional end of the task that the patients ascribed to their activity. The other 25% tailless rituals comprised a relatively high number and higher rate of repetition of non-functional acts. Thus, in rituals with tail, incompleteness was manifested by the mere presence of the tail whereas in tailless rituals, incompleteness was manifested by the reduced functionality of the task due to an inflated execution and repetition of non-functional acts. CONCLUSIONS: The prevalence of activity after the functional end ("tail") and the elevated non-functionality in OCD motor rituals support the "lack of stop signal" theories as the underlying mechanism in OCD. Furthermore, the presence and content of the tail might have a therapeutic potential in cognitive-behavior therapy.

Video telemetry and behavioral analysis discriminate between compulsive cleaning and compulsive checking in obsessive-compulsive disorder.

Obsessive-compulsive disorder (OCD) patients exhibit compulsive acts that share key characteristics that discriminate them from normal behaviors. In OCD, factor analysis of symptomatology has identified separate clusters (contamination/cleaning; harming/checking; symmetry/ordering; hoarding). Here we used video analysis of the motor characteristics of OCD compulsions derived from two separate clusters, checking and cleaning, in order to determine whether behavioral differences exist in the way these two compulsions are performed. We compared 22 behavioral components (acts) of 12 OC-cleaning rituals and 25 OC-checking rituals. A normal activity with the identical theme was matched for each OC ritual as a control. For each ritual and control, we measured 22 parameters (such as the duration and frequency of act performance), and the levels of functionality, by evaluating the degree to which the act appears to contribute toward achieving its goal. We found that both OC-cleaning and OC-checking rituals differed from their respective control activity, and that they also differ between themselves in seven out of the 22 parameters. OC-cleaning involved increased repetition of functional activity whereas OC-checking involved a relatively increased non-functional activity. These results suggest that OCD cleaning and checking rituals are sufficiently different to justify their division into different subtypes and presumably are sub-served by different mechanisms. A better understanding of the relationship between those behavioral parameters derived from video-telemetry, and the parameters assessed by means of clinical and neurobiological tools, would improve our understanding of the nosological significance of compulsive symptoms and contribute to advancing endophenotypic exploration of the heterogeneity of OCD.

Are there between-country differences in motor behavior of obsessive-compulsive disorder patients?

BACKGROUND: Cross-cultural factors attributed to obsessive-compulsive disorder (OCD) that are widely investigated around the world are mostly epidemiological, with no respect to the impact of culture on the structure of OCD behavior itself. METHODS: Nine Israeli and nine British OCD patients with respective non-OCD individuals were compared. To determine whether OCD symptoms are consistent across cultures, similarities in behavior were analyzed, as well as differences due to a country effect. In each country, nine OCD patients and nine non-OCD individuals were videotaped while performing the task that the patients attributed to their behavior. RESULTS: Except for a significantly higher rate of repetition and higher performance of idiosyncratic acts, patients from both Israel and the United Kingdom showed high levels of similarities in 22 out of 24 parameters. Compared with Israeli subjects, British OCD patients had significantly longer chains of idiosyncratic acts, and a twice-higher prevalence of brief (1-2 second) idiosyncratic acts. Between-country differences were mild, possibly overridden by the conspicuous impact of OCD pathology, resulting in a similar OCD phenotype. CONCLUSION: These results qualitatively and quantitatively emphasize the universal appearance of the compulsions in OCD symptoms.

Turning order into chaos through repetition and addition of elementary acts in obsessive-compulsive disorder (OCD).

A concept and methodology derived from an animal model provided the framework for a study of rituals in obsessive compulsive disorder (OCD) patients and yielded objective and observable criteria applicable for compulsive rituals across patients. The employed ethological approach should be able to reveal and identify a common structure underlying OCD rituals, pointing to shared psychopathology. Eleven OCD rituals performed by patients in their own home were videotaped and compared with the behaviour of healthy individuals instructed to perform the same rituals. The videotaped rituals were deconstructed into visits to specific locations or objects (ritual space), and to the acts performed at each location/object (ritual basic components). Quantitative analyses revealed that compulsiveness emanates from the expansion of repeats for some acts and visits, and from the addition of superfluous act types. Best discrimination between OCD and control rituals (90.9% success) was provided by the parameter "maximum of act repeats in a ritual" (R(2)=0.77). It is suggested that the identified properties of compulsive behaviour are consistent with a recent hypothesis that ritualized behaviour shifts the individual's attention from a normal focus on structured actions to a pathological attraction onto the processing of basic acts, a shift that invariably overtaxes memory. Characteristics and mechanisms of compulsive rituals may prove useful in objective assessment of psychiatric disorders, behavioural therapy, and OCD nosology.

Rituals, stereotypy and compulsive behavior in animals and humans.

From a survey of the behavior of animals in the wild, in captivity, under the influence of psychoactive drugs and in a model of obsessive-compulsive disorder (OCD), we identify that the behavioral repertoire invariably includes motor rituals, and that such rituals are performed at a few specific locations/objects in the environment with an orderly transition amongst locations/objects. The concept and parameters of this stable organization of rituals in time and space were used to analyze rituals of OCD patients, compared with control individuals performing the same actions (e.g. car locking). It was found that human rituals also converged to a few places/objects where repetitive acts were performed in a regular order, with the acts in OCD patients overlapping with those of control individuals. Across a very diverse range of animals and conditions, motor rituals are thus characterized by their close linkage to a few environmental locations and the repeated performance of relatively few acts. Such similarity in form may reflect a similarity in the mechanisms that control motor rituals in both animals and humans.