ABSTRACT
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. Main-lifetime diagnoses of DSM-III-R and International Statistical Classification of Diseases, 10th Revision schizophrenia were also made. Probandwise concordance rates and correlations in liability were calculated, and biometrical model fitting applied. RESULTS: A substantial genetic contribution to variance in liability was confirmed for the major diagnostic categories except Research Diagnostic Criteria depressive psychosis and unspecified functional psychosis, where familial transmission was confirmed, but the relative contribution of genetic and common environmental factors was unclear. Heritability estimates for Research Diagnostic Criteria schizophrenia, schizoaffective disorder, mania, DSM-III-R schizophrenia, and International Statistical Classification of Diseases, 10th Revision schizophrenia were all between 82% and 85%. None of the estimates differed significantly from any other. CONCLUSIONS: Heritability estimates for schizophrenia, schizoaffective disorder, and mania were substantial and similar. Population morbid risk estimates were inferred rather than directly measured, but the results were very similar to those from studies where morbid risks were directly estimated.
Subject(s)
Diseases in Twins/genetics , Genetic Predisposition to Disease , Psychotic Disorders/genetics , Adult , Bipolar Disorder/diagnosis , Bipolar Disorder/epidemiology , Bipolar Disorder/genetics , Diseases in Twins/diagnosis , Diseases in Twins/epidemiology , Humans , London/epidemiology , Middle Aged , Models, Genetic , Psychiatric Status Rating Scales/statistics & numerical data , Psychotic Disorders/diagnosis , Psychotic Disorders/epidemiology , Registries , Risk Factors , Schizophrenia/diagnosis , Schizophrenia/genetics , Twins, Dizygotic/genetics , Twins, Monozygotic/geneticsABSTRACT
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. METHODS: The IPDE was administered by 58 psychiatrists and clinical psychologists to 716 patients enrolled in clinical facilities at 14 participating centers in 11 countries in North America, Europe, Africa, and Asia. To determine interrater reliability, 141 of the IPDEs (20%) were independently rated by a silent observer. To determine temporal stability, 243 patients (34%) were reexamined after an average interval of 6 months. RESULTS: The IPDE proved acceptable to clinicians and demonstrated an interrater reliability and temporal stability roughly similar to instruments used to diagnose the psychoses, mood, anxiety, and substance use disorders. CONCLUSION: It is possible to assess personality disorders with reasonably good reliability in different nations, languages, and cultures using a semistructured clinical interview that experienced clinicians find relevant, meaningful, and user-friendly.
Subject(s)
Personality Disorders/diagnosis , Psychiatric Status Rating Scales , Adult , Cross-Cultural Comparison , Diagnosis, Differential , Feasibility Studies , Female , Humans , Male , Mental Disorders/classification , Mental Disorders/diagnosis , Middle Aged , Personality Disorders/classification , Pilot Projects , Psychiatric Status Rating Scales/standards , Psychiatric Status Rating Scales/statistics & numerical data , Psychometrics , Reproducibility of Results , Terminology as Topic , United States , United States Substance Abuse and Mental Health Services Administration , World Health OrganizationABSTRACT
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. Among the 220 complete pairs, significantly more probands (25.7%) than co-twins (14.0%) were convicted, although there was no evidence for an independent genetic basis for criminal behaviour. Criminal conviction was significantly related to psychiatric diagnosis. There were specific patterns of offending, particularly among the schizophrenic men, who were also significantly more often convicted (48.6%) than the men with affective psychosis (19.4%), and more likely to receive a prison sentence. The schizophrenic patients were younger at their first conviction (mean age 22.6 years v. 30.8 years) and they had committed more violent offences than the affective group. In both diagnostic groups, ages at first psychiatric contact and first conviction were highly correlated.
