Evidence for a Shared Etiological Mechanism of Psychotic Symptoms and Obsessive-Compulsive Symptoms in Patients with Psychotic Disorders and Their Siblings.

The prevalence of obsessive-compulsive disorder in subjects with psychotic disorder is much higher than in the general population. The higher than chance co-occurrence has also been demonstrated at the level of subclinical expression of both phenotypes. Both extended phenotypes have been shown to cluster in families.

Can obsessions drive you mad? Longitudinal evidence that obsessive-compulsive symptoms worsen the outcome of early psychotic experiences.

Objective: Although there is substantial comorbidity between psychotic disorder and obsessive-compulsive disorder (OCD), little is known about how these clinical phenotypes, and their subclinical extended phenotypes, covary and impact on each other over time. This study examined cross-sectional and longitudinal associations between both (extended) phenotypes in the general population.

Method: Data were obtained from the three waves of the NEMESIS-study.

[...with psychotic features? An investigation into the delusional nature of convictions in patients with non-psychotic disorders].

Background: In certain disorders the boundaries between thoughts, obsessions, overvalued ideas and delusions are not always clearly delineated.

Aim: To find out whether delusions can be distinguished from the convictions that often accompany anorexia nervosa, obsessive compulsive disorder (OCD), body dysmorphic disorder (BDD) and hypochondriasis, all of which apparently may involve impaired reality testing.

Method: The literature was reviewed with the help of PubMed, using as key words 'delusions' in combination with 'hypochodriasis', 'anorexia nervosa', 'body image', 'obsessive compulsive disorder' or 'body dysmorphic disorder'.

Data gathering: biased in psychosis?

This study examined whether the probabilistic reasoning bias referred to as a "jumping-to-conclusions" (JTC) style of reasoning, which, according to previous research, is associated with particular psychotic symptoms such as delusions, represents a trait that can also be detected in nonpsychotic relatives of patients with schizophrenia and in nonpsychotic individuals with a high level of psychotic experiences. Participants were, in order of level of psychosis liability, 40 patients with schizophrenia or a schizoaffective disorder, 40 first-degree nonpsychotic relatives, 41 participants from the general population with above average expression of psychotic experiences, and 53 participants from the general population with an average level of psychotic experiences. A "jumping-to-conclusions" bias was assessed using the beads task.