Cns Spectrums is a peer-reviewed journal that publishes original scientific literature and reviews on a wide variety of neuroscientific topics of interest to the clinician. CNS Spectrums will publish 10 issues In 1997. As the immense prevalence of comorbid diseases among patients seen by psychiatrists and neurologists increases, these physicians will jointly diagnose and treat the neuropsychiatrically ill. Our mission is to provide these physicians with an editorial package that will enhance and Increase their understanding of neuropsychiatry. To this end, manuscripts that address crossover issues germane to neurology and psychiatry will be given immediate priority.

The author reviews both the epidemiology and the genetics of obsessive-compulsive disorder (OCD). A relatively common disorder, OCD has an onset in late adolescence or early adulthood. Its gender distribution is nearly equal, although women are slightly more likely to develop the disorder. Usually chronic, OCD fluctuates depending on factors including the presence of depressed mood or stressful life events. OCD is associated with substantial psychiatric comorbidity, it affects quality of life, and it affects health care utilization. Many questions remain unanswered, such as whether its natural history has changed with the advent of effective therapies, and to what extent patients with OCD are disabled.

There are no adoption studies of OCD, but reports of twins suggest greater monozygotic than dizygotic concordance. Family study results are not entirely consistent, probably because of differences in study methods, but tend to show that OCD is familial. They also show a genetic relationship to subclinical OCD and Tourette's syndrome. Molecular genetic studies are just getting under way. Important issues remain to be answered, including defining the extent of an OCD spectrum of disorders, and determining what constitutes an OCD phenotype.

The author concludes by recommending that further studies on OCD involve samples from the general population rather than clinic- or hospital-based samples, which are inherently biased for severity.

The past 15 years have been exciting for psychiatric researchers interested in the epidemiology and genetics of OCD. Combined with ongoing development of effective pharmacologic and behavioral treatments, new research in these areas has affected how physicians think about OCD, as well as how we clinically manage patients. More work needs to be done, as many important questions about both the epidemiology and genetics of OCD remain unanswered.

The obsessive-compulsive disorders spectrum concept has grown in recent years because of the common clinical features, such as obsessive thinking and compulsive rituals, biological markers, presumed etiology, and treatment response, that these disorders may share with obsessive-compulsive disorder (OCD). This concept has important implications in regard to diagnosis, nosology, neurobiology, and treatment of a wide group of diverse disorders affecting up to 10% of the population. New insights in central nervous system (CNS) mechanisms that drive the repetitive behaviors of the obsessive-compulsive spectrum disorders have heightened interest in the spectrum in researchers, clinicians, and those involved in drug development.

An important approach in neuropsychiatry centers on employing a dimensional classification of psychopathology. Psychiatric phenomena often fall on a continuum. A dimensional approach allows for the classification of patients who fall at the border of classical entities or who are otherwise atypical. Diagnostic categories are considered along a spectrum if there is considerable overlap in symptoms and in etiology, as demonstrated by familial linkage biological markers, and pharmacological dissection. Categorical and dimensional approaches to the OCD spectrum could have significant implications for diagnosis, nosology, neurobiology, and treatment of a wide group of disorders affecting a sizable percentage of the population.

Recent interest has focused on spectrums in movement disorders, affective disorders, schizophrenia, epileptic and impulsive disorders, and obsessive-compulsive disorders (which we will examine here); in addition, there has been interest in the overlap between these spectrums. Viewing disorders in terms of overlapping spectrums provides researchers and clinicians a framework with which to better understand and treat these disorders.

Animal models of obsessive-compulsive disorder may be derived naturally or generated experimentally. Either may be considered a full or partial model, depending on the extent of resemblance to human OCD. Although many models appear to be valid at first glance, complete models should demonstrate “compelling similarities” in all areas examined. Partial models may have only one or two OCD-like features; however, they still provide some opportunities for research. Criteria to consider when evaluating potential models are etiology, symptomatology, and use in indicating methods of therapy and prevention. Demonstration of common underlying physiological mechanisms, patterns of development and expression, and familial associations are some specific elements to consider when assessing the relevance of more complete models.

Cognitive aspects of OCD are difficult, if not impossible, to explore in animals at present and may be quite different from what is found in humans. It is hard to imagine that animals experience ego-dystonicity; however, dogs with acral lick dermatitis (ALD) that have been scolded by their owners will resort to licking themselves when out of sight, implying that they know it is wrong. Because of the difficulty in evaluating an animal's internal state, some adopt the position that there is no complete animal model of OCD and that animal models are at best partial models. However, children who exhibit compulsive behaviors frequently do not experience accompanying obsessions. Even the expression of OCD in children—for example, licking and walking in geometric designs—resembles what is seen in animals.

In the descriptions that follow, only directly comparable aspects of compulsive behavior in animals will be discussed. Naturally occurring models that appear to correspond most closely to full models may be useful in understanding the fundamental mechanisms underlying OCD and the OC spectrum, including genetics and neurobiology. Experimental models, which may be either full or partial models, could contribute similarly or provide limited but specific information in a targeted area of study, depending on the extent of their similarity to OCD.

Recent brain-imaging studies have examined the neuroanatomy and pathophysiology of obsessive-compulsive disorder (OCD). Researchers have used computed tomography and magnetic resonance imaging to look at brain structure and single-photon emission computed tomography and positron emission tomography scanning to look at brain function in OCD subjects. In this article, we review these studies and discuss their methodology. We then present a theoretical model derived from these studies for how the brain mediates OCD symptomatology.

Functional neuroimaging studies have pointed to hyperactivity of orbitofrontal-basal ganglionic–thalamic circuitry in patients with OCD. Our model posits an imbalance between the classical “direct” and “indirect” orbitofrontal–basal ganglionic–thalamic pathways in OCD subjects. The direct circuit appears to function as a positive feedback loop and may “capture” or “lock in” symptomatic OCD subjects. The indirect circuit, which usually provides tonic inhibition to the direct circuit, may be relatively weak.

Finally, we discuss how frontal-subcortical brain circuitry may be involved in other neuropsychiatric illnesses, and we describe how monoamines, such as serotonin and dopamine, may be involved in regulating these circuits in OCD and other illnesses.

A growing body of evidence suggests that obsessive-compulsive disorder (OCD) may be associated with alterations of the serotonin (5-HT) system and that the dorsal raphe nucleus (DRN) may play a role in OCD. In this report, we review this evidence and explore the possible roles of 5-HT and DRN as they relate to OCD.

Despite increased attention to obsessive-compulsive disorder (OCD) in recent years, relatively little work has focused on cross-cultural issues. This paper reports on current thinking in this area, and considers ways of advancing the field.

An important theoretical distinction in medical anthropology is that between “disease” and “illness.” This distinction was employed to help review past cross-cultural studies of OCD and to consider further questions for empirical research. Several studies indicate that the medical disease of OCD is found in a range of cultures, with no apparent need for modification of diagnostic criteria. However, there is almost no work on how OCD as an illness—its subjective perception and experience—varies across cultures. Given the possibility that such variations may influence course and outcome, it is important to attend to them in future work. Further research on OCD needs to address unanswered questions about the epidemiology of the disease and to focus on neglected questions about variations in the subjective illness experience. Cross-cultural variations in illness experience are likely to lead to differences in the path of presentation, and may even result in variations in course and outcome.

Exposure and response prevention (ERP), a form of behavior therapy, is widely recognized as the most effective psychological treatment for obsessive-compulsive disorder (OCD). Cognitive therapy (meaning rational emotive behavior therapy [REBT], or the Salkovskis model for this article) has received increased attention as an effective method for OCD treatment. These methods have renewed hope for patients suffering with what had long been thought to be a treatment refractory condition. Yet many important issues require further discussion and investigation. At the Second International Conference on OCD, which was held in Guadeloupe, February 14–16, 1996, the following issues were highlighted:

1. Which psychotherapies are effective in the treatment of OCD?

2. What psychological strategies may be used to increase patient motivation during treatment?

3. Are relapse prevention strategies necessary after improvement?

4. How do economic factors affect the use of behavior therapy? How is OCD treatment uniform or varying from specialty providers to mental health generalists to primary care physicians? How do self-administered and therapist-administered ERP compare?

5. How does the efficacy of ERP or cognitive therapy and pharmacotherapy (either alone or in combination) compare?

6. Is ERP effective for complex forms of OCD?

7. In OCD treatment, is medication compliance improved if ERP or cognitive therapy is also used, and vice versa? How does this affect relapse rates? In addition, can doses of medications be lowered with the addition of ERP or cognitive therapy?

8. What is known about the brain function and biological changes associated with ERP and cognitive therapy?

Although considered rare and intractable until relatively recently, obsessive-compulsive disorder (OCD) is now recognized as a common condition that can be treated. Clomipramine initially dominated the treatment of OCD, but the introduction of the selective serotonin reup-take inhibitors (SSRIs) now allows OCD to be treated without the unpleasant adverse effects associated with the high doses of clomipramine necessary in OCD. Double-blind, placebo-controlled, and active treatment comparison trials showing the efficacy of fluvoxamine and fluoxetine in particular now provide good reasons to consider SSRIs as first-line therapy for OCD.