Review: Is Schizoaffective Disorder a Distinct Categorical Diagnosis? A Critical Review of the Literature

The featured paper is by Abrams and colleagues and is titled ‘Is Schizoaffective disorder a distinct categorical diagonosis? A critical review of the literature’. The paper is freely available here.

In the introduction the authors discuss the distinction between a dimensional and categorical approach to diagnostic construction. I have reservations about the use of the term neurobehavioural as it seems to infer a movement from the neurological to the behavioural treating the phenomenology as the proverbial black box. Delusions for instance cannot simply be considered as behaviours as there has to be some assessment of meaning in the diagnosis. This is however a small footnote to the main discussion. The authors describe the methodology which involves a search of the PubMed database although the delimiting search years are not given. However it was not clear if the terms given were the complete set and the method for screening papers was mentioned only briefly. Perhaps a table of MeSH terms would remove ambiguity and it would have also been useful to see the number of papers retrieved, screened and used in the final analysis. Nevertheless the authors have done a lot of work to accumulate a vast amount of evidence to support their central argument that a dimensional approach to diagnosis would be more appropriate than a categorical approach to the diagnosis of schizoaffective disorder.

The authors begin with Jacob Kasanin’s meaning of the term schizoaffective psychosis which he compared to schizophrenia and the later development of more than 24 meanings for the term schizoaffective disorder.  The Research Diagnostic Criteria are then discussed with particular reference to how much flexibility in interpretation it offered those using the criteria before the authors move onto the modifcations made in the DSM-III criteria which stipulate that the psychotic symptoms remain for a minimum of two weeks after resolution of the mood component. Next the authors group a disparate group of symptoms and signs into two ‘dimensions’. Thus under the heading thought they group – ‘delusions, hallucinations, disorganized speech and grossly disorganized or catatonic behavior’. This is a rather incongruous grouping as hallucinations are thought of as disturbances of perception and behavior is related but also distinct from thought. One only needs to consider that for thought no actions are necessary while the converse is true for behaviors. Thus this stage in the authors argument isn’t convincing for me. If dimensions are needed, then surely more than two are required. In the subsequent paragraph, the authors cite evidence both for and against the utility of subtle gradations in symptomatology in distinguishing between schizoaffective disorder, schizophrenia and affective psychoses. The naturalistic course of schizoaffective disorder is then examined and the lack of stability of the diagnosis longitudinally is identified and the authors argue that this arises from the use of a categorical approach. The variation in prevalence of schizoaffective disorder found in different studies is considered and again has implications for the diagnosis or else the methodology of the relevant studies. The authors then look at the neurobiology of schizoaffective disorder considering firstly neuropsychological tests which show similar difficulties in cognitive processing between paranoid schizophrenia and schizoaffective disorder. The authors also cite similarities in the structural imaging studies in schizophrenia and schizoaffective disorder. A number of studies in genetics, neurophysiology and neuroendocrinology are covered providing varying degrees of support for the authors’ argument. They look briefly at treatments before concluding that a dimensional approach is suited to schizoaffective disorder.

The paper is thought provoking and probably one that I could interpret differently on reading a second time. This results from the central argument of the appropriateness of a dimensional versus categorical approach to diagnosis which extends beyond schizoaffective disorder. Regardless of whether the argument is valid or not, it functions also to focus the reader in a certain direction when looking at the vast amount of evidence that the authors have assembled.

STT 5 (inform modelling approaches, appropriate model, model informed treatment approaches, clinical testing, successful treatment incorporated into policy)

Steps To Treatment (STT)

STT = Steps To Treatment. An estimate of the number of steps between the results and translation into practice i.e. treatment. This is an opinion.


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The comments made here represent the opinions of the author and do not represent the profession or any body/organisation. The comments made here are not meant as a source of medical advice and those seeking medical advice are advised to consult with their own doctor. The author is not responsible for the contents of any external sites that are linked to in this blog.


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