Philosophers have long struggled with questions about the nature of personal identity and of the self, with some viewing the self as a transcendent entity, and others arguing that the self is a constructed fiction. An approach based in cognitive-affective neuroscience emphasizes that self-related structures and processes are based in the brain-mind, and emerge within the social processes of human development. Alterations in such structures and processes are present in a wide range of neurological and psychiatric disorders, and neuropsychiatric lesion and functional brain imaging studies have led to more detailed awareness of the precise neuronal circuitry underlying self-representations. A cognitive-affective neuroscience approach provides a conceptual basis from which clinical research can further explore how best to assess and treat a wide range of disruptions to the self.

Three patients were seen in an outpatient setting with work difficulties involving disorganization and task completion.They were evaluated and found to have significant symptoms of both attention-deficit/hyperactivity disorder, inattentive subtype and obsessive-compulsive personality disorder and were then treated with a creative combined behavioral and medication treatment, which emphasized the use of external aides (eg, paraprofessionals). Significant symptom reduction was observed as a result of this combined intervention.

Body dysmorphic disorder (BDD) and eating disorders are body image disorders that have long been hypothesized to be related to obsessive-compulsive disorder (OCD). Available data suggest that BDD and eating disorders are often comorbid with OCD. Data from a variety of domains suggest that both BDD and eating disorders have many similarities with OCD and seem related to OCD. However, these disorders also differ from OCD in some ways. Additional research is needed on the relationship of BDD and eating disorders to OCD, including studies that directly compare them to OCD in a variety of domains, including phenomenology, family history, neurobiology, and etiology.

The boundaries between obsessive-compulsive disorder (OCD) and other neuropsychiatric disorders remain unresolved and may well differ from one disorder to another. Endophenotypes are heritable, quantitative traits hypothesized to more closely represent genetic risk for complex polygenic mental disorders than overt symptoms and behaviors. They may have a role in identifying how closely these disorders are associated with another and with other mental disorders with which they share major comorbidity. This review maps the nosological relationships of OCD to other neuropsychiatric disorders, using OCD as the prototype disorder and endophenotype markers, such as cognitive, imaging, and molecular data as well as results from demographic, comorbidity, family, and treatment studies. Despite high comorbidity rates, emerging evidence suggests substantial endophenotypic differences between OCD and anxiety disorders, depression, schizophrenia, and addictions, though comparative data is lacking and the picture is far from clear. On the other hand, strong relationships between OCD, Tourette syndrome, body dysmorphic disorder, hypochondriasis, grooming disorders, obsessive-compulsive personality disorder, and pediatric autoimmune neuropsychiatric disorders associated with streptococcus are likely. Studies designed to delineate the cause, consequences, and common factors are a challenging but essential goal for future research in this area.

In the absence of definitive etiological markers of vulnerability or a unitary profile of pathophysiology for obsessive-compulsive disorder (OCD), obsessive-compulsive (OC) symptom dimensions seem to offer a fruitful point of orientation.The complex clinical presentation of OCD can be summarized using a few consistent and temporally stable symptom dimensions. These can be understood as a spectrum of potentially overlapping features that are likely to be continuous with “normal” worries and extend beyond the traditional nosological boundaries of OCD. Although the understanding of the dimensional structure of obsessive-compulsive symptoms (OCS) is still imperfect, this quantitative approach to phenotypic traits has the potential to advance our understanding of OCD and may aid in the identification of more robust endophenotypes. Preliminary data suggest that these dimensional phenotypes may be useful in studies of the natural history, genetics, neurobiology, and treatment outcome of OCD. A dimensional approach is not mutually exclusive of other methods to parse the larger spectrum of disorders related to OCD. Thus far, age-of-onset of OCS and the individual's “tic-related” status seem to be particularly useful categorical distinctions. Finally, existing assessment methods are inadequate and new dimensional scales are needed to take full advantage of a dimensional approach in clinical and population-based studies.

Epidemiological and clinical data from a variety of cultural and geographic settings on obsessive-compulsive disorder (OCD), and many of the obsessive-compulsive spectrum disorders, suggest that this is a group of disorders with a good degree of transcultural homogeneity. However, the content and themes that predominate in patients with these disorders, and the course of illness, can be shaped by cultural, ethnic, and religious experiences. Across cultures, OCD is commonly comorbid with mood, anxiety, and impulse-control disorders. However, little is known about the mechanisms by which culture and ethnicity may affect the expression of OCD and related disorders. Cross-national comparative studies exploring culturally influenced differences in clinical course, treatment outcome, including ethnogenetic differences in drug response, and prognosis are needed.