Heritability estimates for psychotic disorders: the Maudsley twin psychosis series.

Background: Previous twin studies have supported a genetic contribution to the major categories of psychotic disorders, but few of these have employed operational diagnostic criteria, and no such study has been based on a sample that included the full range of functional psychotic disorders.

Methods: A total of 224 twin probands (106 monozygotic, 118 dizygotic) with a same-sex co-twin and a lifetime history of psychosis was ascertained from the service-based Maudsley Twin Register in London, England. Research Diagnostic Criteria psychotic diagnoses were made on a lifetime-ever basis.

The International Personality Disorder Examination. The World Health Organization/Alcohol, Drug Abuse, and Mental Health Administration international pilot study of personality disorders.

Background: One of the aims of the World Health Organization/Alcohol, Drug Abuse, and Mental Health Administration joint program on psychiatric diagnosis and classification is the development and standardization of diagnostic assessment instruments for use in clinical research worldwide. The International Personality Disorder Examination (IPDE) is a semistructured clinical interview compatible with the International Classification of Diseases, Tenth Revision, and the DMS-III-R classification systems. This is the first report of the results of a field trial to investigate the feasibility of using the IPDE to assess personality disorders worldwide.

A twin study of psychosis and criminality.

Lifetime criminal and psychiatric histories were examined in a consecutive series of 280 individuals of twin birth with a diagnosis of major functional psychosis who were seen and followed up at the Maudsley Hospital between 1948 and 1988. Their 210 co-twins, 35% of whom had a similar diagnosis, were ascertained and followed up over the same period. In the absence of reliable general-population estimates for lifetime conviction rates, co-twins were used as case controls.