The Fourth International Obsessive Compulsive Disorder Conference (IOCDC) was held February 10–12, 2000, on the beautiful island of St. Thomas. The IOCDC is an annual meeting which brings together the world's leading experts in obsessive-compulsive disorder (OCD) and related disorders in a small workshop setting to present recent research advances, discuss gaps in our current knowledge, and plan or international approaches that address these knowledge gaps. The IOCDC meetings have been held on islands on both sides of the Atlantic—Capri, Guadeloupe, Madeira, and now St. Thomas.

The International Organizing Committee consists of Eric Hollander, MD (USA), Joseph Zohar, MD (Israel), and Donatella Marazziti, MD (Italy). The proceedings are generously supported by an unrestricted educational grant from Solvay Pharmaceuticals Inc. and Solvay Pharmaceuticals, and we would like to acknowledge the very important contributions of Chantal Vekens and Mary Blangiardo of Solvay. Also, an mportant part of the success of these meetings stems from the very active role of the chairpersons and cochairpersons of the workshops who lead the discussions, who synthesize the future directions and prepare the manuscripts that result from these discussions that appear in this academic supplement.

The meeting led off with a state-of-the-art plenary address by Mark George, MD (USA), describing how new methods of brain stimulation are improving research and therapy in OCD and promise to revolutionize neuropsychiatric research and herapy over the next decade. He describes how transcranial magnetic stimulation (TMS) is used to test the circuits in OCD and test electrophysiologic evaluations of cortical inhibition n OCD. Newer techniques that are less invasive than ablative surgery and appear promising in OCD therapy include vagus nerve stimulation and deep brain stimulation.

Over the past decade, new functional neuroimaging tools have enabled researchers to identify the specific brain regions involved in obsessive-compulsive disorder (OCD). More recently, researchers have perfected several new techniques for stimulating the brain. With some exceptions, these new brain stimulation techniques are regionally specific and less invasive than older methods. As a class, these “somatic interventions” build on prior neuroanatomic information about OCD. This article reviews the past and current status of these brain stimulation methodologies, which promise to revolutionize neuropsychiatric research and therapy over the next 10 to 20 years. As the brain circuits in OCD and the pharmacology within those circuits become better understood, these brain stimulation techniques hold particular promise in helping to understand and perhaps treat OCD.

Obsessive-compulsive disorder (OCD) is now recognized as a frequent and disabling disorder among children and adolescents. The phenomenology is similar to adult OCD, but several reports have indicated that compulsions are more prominent in children and that children are more inclined than adults to include their family surroundings in ritualistic behavior. It is also clear that young children engage in a significant amount of repetitive, ritualistic compulsive activity that appears to be a normal part of their behavioral repertoire.

Although the cause of childhood-onset OCD is unknown, many factors are likely to contribute to the heterogenous clinical phenotypes, including both genetic and environmental factors. The neurobiological circuitry involved in childhood-onset OCD is likely to involve alterations to the same cortico-striatothalamic circuitry implicated in adult OCD, but the develop-mental differences have yet to be fully delineated. The treatment response patterns of adults and children are generally inconsis-tent with each other, and specific OCD subtypes may also respond differentially.

Phenotypic characterization can be undertaken either categorically, as seen with traditional diagnostic categories, or dimensionally. Extended phenotypes can be defined in terms of symptoms and course of the illness, or neuroimaging and neurobiologic study findings, or treatment responses. Phenotypic characterization must also reflect an understanding of the rituals and repetitive behaviors that are associated with normal development. (A proposed categorization of OCD subtypes appears in the “Table library.”)

The World Health Organization has determined that obsessive-compulsive disorder (OCD) is the 10th leading medical cause of disability across the globe. Unfortunately, a substantial proportion of patients with OCD fail to respond to medication trials. In the pivotal double-blind, placebo-controlled trials that established the efficacy of clomipramine and the selective serotonin reuptake inhibitors (SSRIs), 40% to 60% of patients were nonresponders to a given drug. Moreover, patients who do not respond to their first medication trial may be less likely than treatment-naive patients to respond to subsequent trials. For example, only 33% of patients participating in double-blind trials who had failed trials of one or more serotonin reuptake inhibitors (SRIs) benefited from a subsequent trial of sertra-line, compared with 53% of those who were treatment naive (Rasmussen, Baer, Eisen, and Shera, unpublished data, 15th Annual Meeting, American Psychiatric Association, May 17-22, 1997).

At the Fourth International Obsessive-Compulsive Disorder Conference, held in February 2000 in St. Thomas, US Virgin Islands, an afternoon panel was devoted to considering issues and strategies related to treatment-refractory OCD. The panel presentations were divided into three groups: time to response and outcome after long-term followup; pharmacologic strategies for nonresponders; and new data concerning nonpharmacologic interventions.

This session was divided into two sections. The first explored the neurobiologic basis of stress and stress sensitivity and the second examined the issue of body dysmorphic disorder, a relatively underdiagnosed and poorly understood condition.

The construct of quality of life (QOL), which has both subjective and objective components, has gained increasing importance in psychiatric research for several important reasons, not the least being the current importance of pharmacoeconomic issues. Obsessive-compulsive disorder (OCD) has been suggested to be the worlds 10th most disabling disorder, and pharmacoeconomic studies have indicated that its cost to the world economy runs into the billions of dollars. The use of QOL scales derived from general medicine and other areas of psychiatry has demonstrated the enormous negative impact of OCD on several domains, including occupational function, social function, and family function. Further work to ascertain the extent of changes in QOL during treatment of OCD is necessary.

This manuscript summarizes presentations by an international panel of experts, representing Brazil, Israel, Italy, Mexico, Portugal, Spain, and the United States, at a symposium on obsessive-compulsive disorder (OCD) and its possible subtypes. Presentations concerned both OCD proper, as well as putative obsessive-compulsive-spectrum disorders (autistic disorders, eating disorders, pathological gambling, and schizo-obsessive disorder). Projects discussed included a study assessing impulsive temperament in eating disorder patients, a study on serotonin receptor sensitivity in autism, a study of sleep EEG abnormalities in OCD, a study of dissociation in pathological gamblers, papers on aspects of schizo-obsessive patients, a study addressing biological alterations in OCD, data from a new family study on OCD, data from a molecular genetic study of OCD, a factor analytic study of Tourette disorder, a study hypothesizing the existence of an OCD continuum, and, finally, a paper on early- vs late-onset OCD. General discussion followed leading to a consensus that 1) OCD is likely heterogeneous with multiple subtypes; 2) division of patients by age-at-onset probably represents a robust and valid subtyping scheme; 3) the presence of schizophrenic features probably identifies a valid subtype; 4) the validation of subtypes in the future will be informed by both family-genetic studies, as well as studies of biological alterations in OCD; and 5) the study of obsessive-compulsive spectrum disorders adds to our understanding of the OCD phenomenon, and helps in our search to identify valid subtypes.