The misdiagnosis of schizoaffective disorder

To the Editor

We strongly agree with Malhi and Bell’s (2019) recent article on schizoaffective disorder (SAD) in the ‘fake views’ series. We would like to further the discussion by highlighting the negative consequences of the current situation of what is best termed the misdiagnosis of SAD.

SAD has long been considered as an intermediate condition between mood disorders and schizophrenia. Schizophrenia and SAD are largely indistinguishable in key cognitive, social cognitive and neural realms. The continuing division of these disorders in diagnostic systems and disease models is contentious and requires further attention and delineation.

The clinical reality of the frequent co-occurrence of psychosis and mood episodes has resulted in the over-utilization of a diagnostic category that was originally conceived to be rarely utilized. The common occurrence of psychosis in mood episodes has meant the misdiagnosis of a large proportion of individuals with SAD. In earlier Diagnostic and Statistical Manual of Mental Disorders (DSM) versions, the boundary between schizophrenia and SAD was only qualitatively defined, leading to poor reliability and validity. Phenomenologically, there are no differences in rates of specific types of delusions and hallucinations between subjects with schizophrenia, SAD, psychotic mania and psychotic mixed mania. It is important that we move towards data-based diagnostics by eliminating disorders that have little scientific support. As the primary reason for diagnosis is treatment and SAD has little or no clinical utility.

Kasanin (1994) attempted to break with the established dogma of the time that hallucinations and/or delusions meant schizophrenia and alluded to the relatively rare occurrence of SAD. Paradoxically, this is now the most common diagnosis in our public mental health system. As such polypharmacy is an inevitable consequence. Patients misdiagnosed with SAD are likely to receive more antipsychotic medications for longer periods of time than patients with a bipolar disorder diagnosis. This is an issue as a high proportion of these patients misdiagnosed with SAD have bipolar disorder.

Atypical antipsychotics are commonly prescribed. Thus, patients experience more disabling side effects that are worse than the side effects associated with antidepressants and the mood stabilizers, drugs which are usually prescribed to treat bipolar disorders. Thus, the consequences of the misdiagnosis of SAD are especially severe for patients who actually have bipolar disorder. These issues call for an approach that incorporates a strong differential diagnosis, trying to avoid what Malhi and Bell highlighted as a high proportion of patients being diagnosed with SAD as the differential diagnosis but also the primary diagnosis. Furthermore, prescription of antipsychotics to patients should be tapered, and patients should be discontinued from antipsychotic treatment once psychotic symptoms resolve. This will lead to less individuals being diagnosed with SAD, identifying misdiagnosis earlier and improvements for the treatment of this group.