Gin S. Malhi: A critical analysis of concepts in psychiatry.
Gin S.Malhi and Erica Bell: Schizoaffective disorder in not "SAD" just bad
Janusz K. Rybakowski comment
I read with great interest the Gin Malhi and Erica Bell essay on schizoaffective disorder, with their proposal for the term "schizoaffective dysfunction."
Indeed, since the paper of Kasanin (1933) on schizoaffective psychosis, there has been long-lasting controversy about this nosological entity and the studies of the recent two decades have not brought about definite conclusions. For example, Brazilian authors (Cheniaux, Landeira-Fernandez, Lessa Telles et al. 2008) performed a systematic review of 49 studies that compared schizoaffective disorders with schizophrenia or mood disorder. Evaluation of demographic characteristics, symptomatology, other clinical data, dexamethasone suppression test, neuroimage exams, response to treatment, evolution and family morbidity indicated that schizoaffective disorder occupies an intermediate position between schizophrenia and mood disorders. The analysis indicated that schizoaffective disorder cannot be interpreted as an atypical form of schizophrenia or mood disorder and does not appear to represent either their co-morbidity or an independent mental disorder. The authors argued that schizoaffective disorder might constitute a heterogeneous group composed of both schizophrenia and mood disorder patients or a middle point of a continuum between these two entities.
In another study, Keshavan, Morris, Sweeney et al. (2011) devised a brief descriptive scale based on the type and relative proportions of psychotic and affective symptoms over the illness course and administered it to a series of 762 patients with psychotic disorders, including schizophrenia, schizoaffective and psychotic bipolar disorder. The resulting Schizo-Bipolar Scale scores across these disorders showed neither a clear dichotomy nor a simple continuous distribution. While the majority of cases had ratings close to prototypic schizophrenia or bipolar disorder, a large group (45% of cases) fell on the continuum between these two prototypes.
Of interest are two papers by German authors on test-retest reliability and heterogeneity of schizoaffective disorders. The results of the first one (Santelmann, Franklin, Bußhoff and Baethge 2015) are quoted by Malhi and Bell as evidence of low diagnostic reliability of schizoaffective disorder. However, in the second one (Rink, Pagel, Franklin and Baethge 2016) the authors found the heterogeneity of schizoaffective disorder not larger than schizophrenia or unipolar depression. Furthermore, they concluded that schizoaffective disorder falls between schizophrenia and affective disorders and there are relevant quantitative differences in key illness characteristics, which supports the validity of the schizoaffective illness concept. Cardno and Owen (2014), in their paper on the genetic relationships between schizophrenia, bipolar disorder and schizoaffective disorder, conclude that schizoaffective disorder shows substantial familial overlap with both schizophrenia and bipolar disorder. A twin analysis shows shared genetic influences on schizophrenic and manic episodes, while association studies show such influences on the broadly defined schizoaffective disorder, bipolar type.
In conclusion, I am skeptical about the significant clinical implication of introducing the term "schizoaffective dysfunction" allowing to remain the acronym “SAD.” It should be also mentioned that this acronym was firstly used in the context of “seasonal affective disorder” (Rosenthal, Sack, Gillin et al. 1984) and has been widely functioning in such connotation until now.
What is badly needed is a genome-wide association study (GWAS) in schizoaffective disorder. The test for the specificity of schizoaffective disorder would be finding the genes which are not associated either with schizophrenia or bipolar disorder.
References:
Cardno AG, Owen MJ. Genetic relationships between schizophrenia, bipolar disorder, and schizoaffective disorder. Schizophr Bull, 2014; 40:504-15.
Cheniaux E, Landeira-Fernandez J, Lessa Telles L, Lessa JL, Dias A, Duncan T, Versiani M. Does schizoaffective disorder really exist? A systematic review of the studies that compared schizoaffective disorder with schizophrenia or mood disorders. J Affect Disord, 2008; 106:209-17.
Kasanin J. The acute schizoaffective psychoses. Am J Psychiatry, 1933; 90:97-126.
Keshavan MS, Morris DW, Sweeney JA Pearlson G, Thaker G, Seidman LJ, Eack SM, Tamminga C. A dimensional approach to the psychosis spectrum between bipolar disorder and schizophrenia: the Schizo-Bipolar Scale. Schizophr Res, 2011; 133:250-4.
Rink L, Pagel T, Franklin J, Baethge C. Characteristics and heterogeneity of schizoaffective disorder compared with unipolar depression and schizophrenia - a systematic literature review and meta-analysis. J Affect Disord, 2016; 191;8-14.
Rosenthal NE, Sack DA, Gillin JC, Lewy AJ, Goodwin FK, Davenport Y, Mueller PS, Newsome DA, Wehr TA. Seasonal affective disorder. A description of the syndrome and preliminary findings with light therapy. Arch Gen Psychiatry, 1984; 41:72-80.
Santelmann H, Franklin J, Bußhoff J, Baethge C. Test-retest reliability of schizoaffective disorder compared with schizophrenia, bipolar disorder, and unipolar depression--a systematic review and meta-analysis. Bipol Disord, 2015; 17: 755-68.
June 18, 2020