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Biomedical subjects

A E Farmer

Publications and source records attributed to A E Farmer.

At least 19 recordsLinked to original sources
PubMed1999

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. 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.

Adult↗
PubMed1996

Further exploration of a latent class typology of schizophrenia.

We previously derived a typology of schizophrenia from a latent class analysis of 447 first-contact non-affective functional psychotic patients from a defined catchment area. Here, using the same sample, we show that the three subtypes, 'neurodevelopmental' (Type A), 'paranoid' (Type B) and 'schizoaffective' (Type C) have different premorbid, phenomenological and treatment response characteristics. A canonical variate analysis of the three subtypes achieved partial separation between the first two subtypes, but the 'schizoaffective' type was less distinct.

Adult↗
PubMed1996

A multicentre inter-rater reliability study using the OPCRIT computerized diagnostic system.

We examined the reliability of the OPCRIT system from ratings produced by 30 USA and European clinicians involved in molecular genetic research. The OPCRIT system facilitates a polydiagnostic approach to research on severe psychiatric disorders. OPCRIT comprises a 90-item checklist of signs and symptoms and a suite of computer programs, which together generate diagnoses according to the operational criteria of 12 major classificatory systems (e.g. DSM-III, DSM-III-R, RDC, ICD-10). Thirty summaries of actual cases ranging in signs and symptoms, taken from independent sources, were rated by participants from research centres across Europe and the USA using the OPCRIT system. Each rating was then compared to a standard rating using a kappa statistic. Good levels of reliability were observed within all classifications (e.g. DSM-III-R, kappa = 0.73, RDC, kappa = 0.71; ICD-10, kappa = 0.70) and a similar pattern of ratings was found in both the European and USA samples. We conclude that the OPCRIT system, is both flexible and practicable retaining the 'top-down' advantage of operational definitions as well as the 'bottom-up' potential offered by well defined signs, symptoms and other component items. Within the limitations of an international, multicentre design this study shows that the OPCRIT system affords good reliability with raters from a variety of geographical and theoretical backgrounds.

Diagnosis, Computer-Assisted↗
PubMed1996

Concurrent validity of the OPCRIT diagnostic system. Comparison of OPCRIT diagnoses with consensus best-estimate lifetime diagnoses.

BACKGROUND: OPCRIT (a suite of computer programs that allow data entry and generate diagnoses according to 12 operational diagnostic systems) is used in a wide range of psychiatric research including both European Science Foundation and NIMH research initiatives in the molecular genetics of mental disorders. We examined its concurrent validity in 100 subjects collected for linkage studies of Bipolar Disorder and Schizophrenia. METHOD: We compared diagnoses generated by OPCRIT from data rated by two trained clinicians with diagnoses made according to consensus, best-estimate, lifetime procedures by the same two raters according to DSM-III-R and RDC classifications. RESULTS: Good to excellent agreement was achieved between OPCRIT diagnoses and those made by consensus best-estimate procedures. CONCLUSIONS: OPCRIT provides a convenient, reliable, rapid and valid approach to polydiagnostic assessment that can be used as an adjunct to conventional (but time consulting) best-estimate consensus diagnostic procedures.

Bipolar Disorder↗
PubMed1994

Phenotypic definitions of psychotic illness for molecular genetic research.

New approaches to establish the molecular genetic bases of psychotic illness have recently been suggested which make different demands on diagnosticians attempting to provide reliable and valid phenotypic definitions. The diagnostic problems that have arisen to date and some solutions to these are considered. In addition, future diagnostic requirements for linkage and association studies are discussed.

Cognition↗
PubMed1993

Heterogeneity in schizophrenia: an extended replication of the hebephrenic-like and paranoid-like subtypes.

Hebephrenic-like (H) and paranoid-like (P) subtypes of schizophrenia have previously been described by Farmer et al. (1983, 1984). The stability of this subtypology of schizophrenia was explored using multivariate statistical techniques on a large independent data set. Both a discriminant function analysis and an admixture analysis produced strong evidence for a bimodel distribution of scores consistent with the H-like and P-like subtypes.

Adult↗
PubMed1993

Drug treatment of resistant schizophrenia. Limitations and recommendations.

Despite the advances achieved since the introduction of chlorpromazine, schizophrenia may respond inadequately to standard drug treatments. The reasons for this include noncompliance, poor tolerance and the development of distressing side effects or the resistance of the illness itself. Treatment-resistant schizophrenia is increasingly the focus of new research developments. The older or classic antipsychotic drugs have a broad spectrum of action on central and peripheral nervous system receptors. Their action on dopamine receptors was an early clue to the pathogenesis of schizophrenia. More recently, multiple subtypes of dopamine receptors have been identified. These, plus serotonin receptors, have been identified in brain structures thought to be implicated in schizophrenic illnesses. Atypical antipsychotic agents whose pharmacological action is either more specific, or which have novel receptor binding profiles show characteristic effects in both animal models and clinically. These drugs may improve symptoms in otherwise resistant illness or where intolerance prevents the use of standard treatments. There are a number of adjunctive somatic treatment strategies using established agents such as lithium and electroconvulsive therapy the use of which is now being explored systematically. The most exciting current development is the re-emergence of clozapine as a highly effective atypical antipsychotic drug which can be used safely if special surveillance is undertaken to monitor for its potentially severe toxic effects. These recent advances offer hope of improvement in the prognosis of people suffering from severe and intractable forms of schizophrenia.

Antipsychotic Agents↗
PubMed1992

Labelling and illness in primary care: comparing factors influencing general practitioners' and psychiatrists' decisions regarding patient referral to mental illness services.

GPs and psychiatrists from South Wales were asked to make decisions based on the information included in each of 16 vignettes describing depressed and anxious subjects. This information contained randomly assigned sex, psychiatric label, good and bad psychosocial context and age as well as eight different severity ratings of depression and anxiety symptoms. Our results showed that both GPs and psychiatrists were influenced in their decision making by the severity of the illness, but that GPs alone were also strongly influenced by the presence of male sex and by the presence of a psychiatric label. Good or bad psychosocial context had no influence on the GPs' referral decision, and previous experience in psychiatry or other vocational training had no detectable effect, but this may be because of the sample size.

Adult↗
PubMed1992

Methodological issues in using a polydiagnostic approach to define psychotic illness.

Although a polydiagnostic approach to the definition of psychotic disorder provides many advantages to the researcher, there are also disadvantages. A comparison between several different sets of operational criteria using the OPCRIT computer program on a consecutive series of 397 psychotic subjects is described. The results show that although current diagnostic procedures are generally reliable, such approaches can still only supplement skilled clinical judgement, and there remain many pitfalls for the unwary.

Humans↗
PubMed1991

Clinical polydiagnostic studies in a large Swedish pedigree with schizophrenia.

A polydiagnostic computerized diagnostic system for psychosis was used in a Swedish family complex, and 51 patients with psychiatric symptomatology were examined with eight main diagnostic systems for schizophrenia and three systems for schizophrenic subgroups. All patients fulfilled the criteria for schizophrenia according to Taylor et al., 50 according to Carpenter, 41 according to RDC, and 31 of the 51 according to DSM-III and DSM-III-R. The hypothesis that the patients in the Swedish family complex differ from other phenotypes of schizophrenia must be refuted based on the data of the present study.

Adult↗
PubMed1991

Comparison of CATEGO-derived ICD-8 and DSM-III classifications using the composite international diagnostic interview in severely ill subjects.

Two classifications, DSM-III and CATEGO4-derived ICD-8, included in the CIDI, are compared in 63 in-patients and out-patients with a broad range of psychiatric illness. Agreement for main diagnosis between these classifications was statistically significant for two time frames, the present state and lifetime. However, while diagnostic assignment by CATEGO4 remained fairly constant between time frames, there was a marked shift in DSM-III-assigned diagnosis, with cases changing from anxiety state diagnosis (present state) to affective disorder (lifetime). Thirty-nine subjects were assigned a DSM-III diagnosis of affective disorder for lifetime illness compared with 21 assigned to this diagnostic group by CATEGO4.

Adolescent↗
PubMed1988

The pathogenesis and management of schizophrenia.

Schizophrenia remains a relatively common debilitating and stigmatising disorder, whose precise aetiology is unknown. Research has consistently shown a strong genetic component, although environmental factors are also implicated. A number of biochemical aetiological theories have been proposed but the most plausible is the dopamine hypothesis. This suggests that there is excess activity at central dopaminergic pathways in the brain. Certainly, all effective antipsychotic drugs have dopamine blocking properties. Management of this disorder includes admitting new cases to hospital for careful evaluation by a multidisciplinary team. Although the mainstay of treatment is antipsychotic (neuroleptic) medication, social interventions are also required. These include close liaison with the patient's family, which can help to prevent relapse and aid compliance with drug treatment. Modern therapy aims for recovery of social and occupational skills and gradual rehabilitation back into the community.

Antipsychotic Agents↗
PubMed1987

Twin concordance for DSM-III schizophrenia. Scrutinizing the validity of the definition.

DSM-III diagnoses were applied to 26 monozygotic (MZ) and 34 dizygotic (DZ) probands and their co-twins from the Maudsley Hospital (1948 to 1965) schizophrenic series of Gottesman and Shields. DSM-III criteria for schizophrenia were found to be highly reliable and valid, and to have a broad heritability of 0.85, which is comparable with the Research Diagnostic Criteria and Feighner criteria from which they were derived. When the full range of DSM-III diagnoses were considered, both affective disorder and schizophrenia were found in genetically identical individuals. The effect of DSM-III nosology on the twin series was also explored by adding other diagnoses to that of schizophrenia and observing the effect on the MZ/DZ concordance ratio. The addition of affective disorder with mood-incongruent delusions to the schizophrenia spectrum produced the largest increase in the ratio and, by implication, a "more genetic" combination than schizophrenia alone. The maximum MZ/DZ concordance ratio (7.68) was produced by schizophrenia, plus affective disorder with mood-incongruent delusions, plus schizotypal personality disorder, plus atypical psychosis. The effect of adding paranoid disorder (paranoia) and all other affective categories was a reduction in the ratio.

Adult↗