This manuscript summarizes the presentations of an international panel of experts, representing France, Hungary, India, South Africa, and the United States, on obsessive-compulsive disorder (OCD). OCD is culturally universal but probably heterogeneous. New data presented concern a follow-up study from a joint Yale-Brown clinical project; a prevalence study in Hungary; a molecular genetics study from South Africa; a comorbidity study from India; a clinical study from Paris comparing OCD with subclinical OCD; a discussion of compulsive buying as a cross-cultural phenomenon; and survey results showing the impact of OCD on quality of life and economic variables. A roundtable discussion led to a consensus that researchers must continue to: (1) investigate the prevalence of OCD in non Western samples and in less developed countries; (2) collect clinical data on OCD in child and adolescent samples, as well as in off-spring of adults with OCD; (3) refine the concept of age of onset; (4) study the impact of OCD on quality of life and the economy; (5) investigate the validity of the obsessive-compulsive spectrum in epidemiologic and clinical samples and develop appropriate instruments for its assessment; (6) study personality disorder and how it affects treatment response, and examine its prevalence in epidemiologic samples; (7) explore the concept of OCD heterogeneity, which may reflect differing etiologies but may also suggest differential treatment strategies; (8) conduct follow-up studies, particularly now that effective treatments may alter course of illness; and, finally, (9) investigate treatment response and whether certain subtypes demand unique approaches.

Workshop 2, “Childhood and OCD,” focused on six areas of research of special relevance to children: phenomenology, age of onset, subtypes, infectious and immune etiologies, psychosocial treatments, and medication treatments. Overarching themes in this session were the relative paucity of research in children and adolescents with obsessive-compulsive disorder (OCD) in comparison to adults and the unique potential for research in children to provide answers to important questions about the etiology, subtypes, pathophysiology, and treatment of OCD.

Two symptom clusters within the obsessive-compulsive (OC) spectrum—the impulsive cluster and the schizo-obsessive cluster—are discussed in this paper. Disorders characterized by impulsivity include disorders of impulse control (eg, intermittent explosive disorder, pyromania, kleptomania, pathologic gambling, trichotillomania); paraphilias, sexual impulsions, and sexual addictions; and impulsive aggression personality disorders (eg, borderline, antisocial, histrionic, and narcissistic personality disorders). The schizo-obsessive cluster includes comorbid symptoms of obsessive-compulsive disorder (OCD) and schizophrenia. Both clusters of disorders have a substantial impact on individuals and society. This article examines the overlap of symptoms between OCD and OC spectrum disorders, along with possible treatment options. Studies on the effectiveness of serotonin reuptake inhibitors in treating pathologic gambling, compulsive buying, and comorbid OCD and schizophrenia are presented. The need for additional large scale, adequately-controlled studies is discussed.

The “Genetics of Obsessive-Compulsive Disorder” session at the Third International Obsessive-Compulsive Disorder Conference focused on the strong evidence of familial transmission of obsessive-compulsive disorder (OCD) and the new strategies available for molecular genetic research in this area. The opportunity to create a truly collaborative approach to the genetic study of OCD with standard methodology and large-scale cooperation among groups was emphasized. The importance of phenotype definition, including systematic subtyping, was discussed in the context of reducing heterogeneity and false-positive results.

A summary of the Third International Obsessive Compulsive Disorder Conference proceedings on neuroimaging research and neurocircuitry models of obsessive-compulsive disorder (OCD) is presented. This survey of recent and ongoing research indicates that a wide range of modern techniques and experimental strategies are being employed in a complementary fashion to enhance our understanding of OCD. Imaging studies in animal models of OCD are helping to elaborate relevant normal anatomy and neuro-chemistry. Functional imaging methods are being employed in conjunction with behavioral, pharmacologic, and cognitive challenge paradigms. Magnetic resonance spectroscopy as well as radiotracer methods are being utilized to measure neurochemical and neuropharmacologic indices in OCD. Transcranial magnetic stimulation has emerged as a tool for probing neurocircuitry that may also have therapeutic potential. Experimental designs and data-analytic methods are evolving to help elucidate the pathophysiology of OCD and related disorders, delineate neurobiologically meaningful subtypes of OCD, and identify potential predictors of treatment response. Collectively, these efforts promise important advances as we approach the new millennium.

Obsessive-compulsive disorder (OCD) has long been considered a treatment-refractory mental condition. Neither pharmacologic nor psychodynamic therapy has been proven to treat OCD effectively. Yet the prognosis for OCD has changed dramatically in recent years with the introduction of behavior therapy and the use of selective serotonin reuptake inhibitors (SSRIs). Many studies have shown that behavior therapy, especially exposure with response prevention, and SSRIs reduce obsessive-compulsive symptoms significantly. Still, many unanswered questions—including the role of cognitive therapy in the treatment of OCD, exposure therapy vs multimodal behavioral therapy, individual versus group therapy, outcome predictors in adults, adolescents, and children, and the role of combination treatment using an SSRI and cognitive-behavioral therapy—remain. This article will explore these issues as well as suggest directions for further research into OCD.

There is evidence supporting the presence of abnormalities in certain neurotransmitters, such as dopamine and noradrenaline, and in neuropeptides and other mechanisms, such as the immune system in patients with obsessive-compulsive disorder (OCD). However, the findings implicating serotonin (5-hydroxytryptamine [5-HT]) in the pathophysiology of OCD are increasing at a rate not found in any other psychiatric disorder. These abundant findings foster numerous complex questions that await answers. For example, which 5-HT receptor subtypes or other subcomponents of the 5-HT system are principally involved in OCD pathophysiology, and how do they interact with dysfunctions of other systems? In the search for answers to these critical questions, experimental pharmacology represents a key tool for approaching the complexity of the involvement of 5-HT in OCD, and also suggests new potential therapeutic targets. This article summarizes, in part, the presentations and the discussion of the symposium, “Experimental Pharmacology in OCD,” which was held during the Third International OCD Conference meeting in Madeira, Portugal, in September 1998.

All the research to date implicates serotonin as the major neurotransmitter involved in obsessive-compulsive disorder (OCD). Much of the evidence has come from clinical treatment studies, which have shown the specific antiobsessional effect of drugs that are potent inhibitors of serotonin reuptake. Only the selective serotonin reuptake inhibitors (SSRIs) and the potent inhibitors of serotonin reuptake have been shown to be effective in treating patients with OCD. Serotonin receptor inhibitors and SSRIs have been thoroughly investigated in short- and long-term placebo-controlled studies and all have been found to be effective in OCD.