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

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, 118 same-sex dizygotic), 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 monozygotic pairs, and a trend for schizoaffective-mania and mania to have the greatest co-occurrence. Schizoaffective syndromes in monozygotic 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.

Behavior Genetics of Psychopathology

“…Individuals with schizoaffective mania may have broad aetiological factors that increase risk of both schizophrenia and bipolar disorder and/or the co-occurrence of relatively specifi c aetiological factors for schizophrenia and bipolar disorder. The same twin analysis was also consistent with schizoaffective depression being due to co-occurring elevated liability to schizophrenia and depression, but with less elevation of liability to mania (Cardno et al, 2012 ).…”

“…Further twin analysis of the manic and depressive subtypes of schizoaffective disorder in the same sample was consistent with schizoaffective mania being due to co-occurring elevated liability to schizophrenia, mania, and depression (Cardno et al, 2012 ), at least in terms of familial/genetic aetiological factors. Individuals with schizoaffective mania may have broad aetiological factors that increase risk of both schizophrenia and bipolar disorder and/or the co-occurrence of relatively specifi c aetiological factors for schizophrenia and bipolar disorder.…”

Identification of Distinct Psychosis Biotypes Using Brain-Based Biomarkers

“…Even bipolar disorder with psychosis and schizophrenia, the two major and ostensibly distinct psychosis categories, do not “breed true” (10,11). There is overlap in susceptibility genes and phenotypes across bipolar disorder with psychosis and schizophrenia (12–14) and considerable similarity between different psychotic disorders on symptoms, illness course, cognition, psychophysiology and neurobiology (15–26).…”

Brain functional abnormality in schizo-affective disorder: an fMRI study

“…One traditional method for resolving such uncertainties, family history studies, has not provided decisive support for any of these positions : first-degree relatives of schizo-affective patients have variously been found to show elevated rates of schizophrenia, affective disorder or both illnesses (Coryell & Zimmerman, 1988 ;Maier et al 1993 ;Kendler et al 1995 ;Laursen et al 2005). Similarly, examples of all forms of psychotic disorder are seen among the monozygotic co-twins of patients with schizo-affective disorder (Cardno et al 2012).…”