A twin study of schizoaffective-mania, schizoaffective-depression, and other psychotic syndromes

Alastair G. Cardno, Frühling V. Rijsdijk, Robert M. West, Irving I. Gottesman, Nick Craddock, Robin M. Murray, Peter Mcguffin

Research output: Contribution to journalArticlepeer-review

23 Scopus citations

Abstract

The nosological status of schizoaffective disorders remains controversial. Twin studies are potentially valuable for investigating relationships between schizoaffective-mania, schizoaffective-depression, and other psychotic syndromes, but no such study has yet been reported. We ascertained 224 probandwise twin pairs [106 monozygotic (MZ), 118 same-sex dizygotic (DZ)], where probands had psychotic or manic symptoms, from the Maudsley Twin Register in London (1948-1993). We investigated Research Diagnostic Criteria schizoaffective-mania, schizoaffective-depression, schizophrenia, mania and depressive psychosis primarily using a non-hierarchical classification, and additionally using hierarchical and data-derived classifications, and a classification featuring broad schizophrenic and manic syndromes without separate schizoaffective syndromes. We investigated inter-rater reliability and co-occurrence of syndromes within twin probands and twin pairs. The schizoaffective syndromes showed only moderate inter-rater reliability. There was general significant co-occurrence between syndromes within twin probands and MZ pairs, and a trend for schizoaffective-mania and mania to have the greatest co-occurrence. Schizoaffective syndromes in MZ probands were associated with relatively high risk of a psychotic syndrome occurring in their co-twins. The classification of broad schizophrenic and manic syndromes without separate schizoaffective syndromes showed improved inter-rater reliability, but high genetic and environmental correlations between the two broad syndromes. The results are consistent with regarding schizoaffective-mania as due to co-occurring elevated liability to schizophrenia, mania, and depression; and schizoaffective-depression as due to co-occurring elevated liability to schizophrenia and depression, but with less elevation of liability to mania. If in due course schizoaffective syndromes show satisfactory inter-rater reliability and some specific etiological factors they could alternatively be regarded as partly independent disorders.

Original languageEnglish (US)
Pages (from-to)172-182
Number of pages11
JournalAmerican Journal of Medical Genetics, Part B: Neuropsychiatric Genetics
Volume159 B
Issue number2
DOIs
StatePublished - Mar 2012

Keywords

  • Bipolar disorder
  • Depressive psychosis
  • Genetics
  • Schizoaffective disorder
  • Schizophrenia

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