The new Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-5) has a number of changes to schizophrenia and other psychotic disorders. This article outlines some of the major changes to these conditions.
According to the American Psychiatric Association (APA), the publisher of the DSM-5, some of the biggest changes in this chapter were made to better refine the diagnostic criteria based upon the past decade and a half of schizophrenia research.
Two changes were made to the primary symptom criteria for schizophrenia.
According to the APA, “the first change is the elimination of the special attribution of bizarre delusions and Schneiderian first-rank auditory hallucinations (e.g., two or more voices conversing). In DSM-IV, only one such symptom was needed to meet the diagnostic requirement for Criterion A, instead of two of the other listed symptoms. This special attribution was removed due to the nonspecificity of Schneiderian symptoms and the poor reliability in distinguishing bizarre from nonbizarre delusions.
“Therefore, in DSM-5, two Criterion A symptoms are required for any diagnosis of schizophrenia.”
The second change was the requirement for a person to now have at least one of three “positive” symptoms of schizophrenia:
- Disorganized speech
The APA believes this helps increase the reliability of a schizophrenia diagnosis.
Schizophrenia subtypes have been dumped in the DSM-5 because of their “limited diagnostic stability, low reliability, and poor validity,” according to the APA. (The old DSM-IV had specified the following schizophrenia subtypes: paranoid, disorganized, catatonic, undifferentiated, and residual type.)
The APA also justified the removal of schizophrenia subtypes from the DSM-5 because they didn’t appear to help with providing better targeted treatment, or predicting treatment response.
The APA proposes that clinicians instead use a “dimensional approach to rating severity for the core symptoms of schizophrenia is included in Section III to capture the important heterogeneity in symptom type and severity expressed across individuals with psychotic disorders.” Section III is the new section in the DSM-5 that includes assessments, as well as diagnoses needing further research.
The biggest change to schizoaffective disorder is that a major mood episode must be present for a majority of the time the disorder has been present in the person.
The APA says this change was made on “both conceptual and psychometric grounds. It makes schizoaffective disorder a longitudinal instead of a cross-sectional diagnosis — more comparable to schizophrenia, bipolar disorder, and major depresive disorder, which are bridged by this condition. The change was also made to improve the reliability, diagnostic stability, and validity of this disorder, while recognizing that the characterization of patients with both psychotic and mood symptoms, either concurrently or at different points in their illness, has been a clinical challenge.”
Mirroring the change in the schizophrenia diagnostic criteria, delusions in delusion disorder are no longer required to be of the “non-bizarre” type. A person can now be diagnosed with delusional disorder with bizarre delusions, via a new specifier in the DSM-5.
So how does a clinician make a differential diagnosis from other disorders, such as body dysmorphic disorder or obsessive-compulsive disorder? Easy — through a new exclusion criterion for delusional disorder, which states that the symptoms “must not be better explained by conditions such as obsessive-compulsive or body dysmorphic disorder with absent insight/delusional beliefs.”
Also, the APA notes that the DSM-5 no longer “separates delusional disorder from shared delusional disorder. If criteria are met for delusional disorder then that diagnosis is made. If the diagnosis cannot be made but shared beliefs are present, then the diagnosis other specified schizophrenia spectrum and other psychotic disorder is used.”
According to the APA, the same criteria are used to diagnose catatonia whether the context is a psychotic, bipolar, depressive, or other medical disorder, or an unidentified medical condition:
In DSM-IV, two out of five symptom clusters were required if the context was a psychotic or mood disorder, whereas only one symptom cluster was needed if the context was a general medical condition. In DSM-5, all contexts require three catatonic symptoms (from a total of 12 characteristic symptoms).
In DSM-5, catatonia may be diagnosed as a specifier for depressive, bipolar, and psychotic disorders; as a separate diagnosis in the context of another medical condition; or as an other specified diagnosis.