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In DSM-IV,1 the section on schizophrenia and other psychotic disorders includes schizophrenia (with 5 subtypes), schizophreniform disorder, schizoaffective disorder, delusional disorder, shared psychotic disorder, brief psychotic disorder, substance-induced psychotic disorder, psychotic disorder due to a general medical condition, and psychotic disorder not otherwise specified. As we consider proposed changes to DSM-5 (Table 1),2 it is useful to consider limitations in our current construct of schizophrenia.
Table 1
Psychotic disorders in DSM-5: Summary of proposed changes
| Replace existing subtypes with dimensions |
| Include diagnosis of attenuated psychosis syndrome |
| Modify criteria for schizoaffective disorder |
| ‘Delink’ catatonia from schizophrenia |
| Source: Reference 2 |
First, many etiological factors and pathophysiological processes appear relevant to what we consider schizophrenia and it is almost certain that our construct of schizophrenia encompasses not one but numerous diseases with a shared phenotype.3-5
Second, the boundary between schizophrenia and schizoaffective disorder is imprecisely defined, and a proportion of patients with schizophrenia with some mood symptoms may inappropriately receive a schizoaffective disorder diagnosis. This is compounded by the poor reliability and low diagnostic stability of a schizoaffective disorder diagnosis.6-8
Third, the current classic schizophrenia subtypes provide an inadequate description of the enormous heterogeneity of this condition. Additionally, subtype stability is low, and only the paranoid and undifferentiated subtypes are used frequently in clinical practice.
Fourth, the prominence given to Schneiderian first-rank symptoms (“bizarre” delusions or “special” hallucinations) appears misplaced.
Fifth, the current construct of schizophrenia inadequately describes the major psychopathological dimensions of the condition and stages of its evolution.8,9
Finally, the current clinical construct of schizophrenia does not match neurobiological markers and genetic findings or specific pharmacological treatment provided.5,10 Proposed DSM-5 revisions2 to the definition of schizophrenia to address these limitations are summarized below.
Schizophrenia syndrome
Proposed changes to the diagnostic criteria for schizophrenia are modest and continuity with DSM-IV is broadly maintained. Two modest changes to criterion A (active phase symptoms) are proposed:
- Eliminate special treatment of bizarre delusions and other Schneiderian first-rank symptoms. In DSM-IV, only 1 criterion A is required if it is a bizarre delusion or hallucination. Because Schneiderian first-rank symptoms do not have diagnostic specificity and diagnosing “bizarreness” of delusions and hallucinations has low reliability, it is proposed that these positive symptoms be treated like any other with regard to their diagnostic implications.
- Require that at least 1 of the 2 symptoms required to meet criterion A be delusions, hallucinations, or disorganized thinking. These are core positive symptoms diagnosed with high reliability and might reasonably be considered necessary for a reliable schizophrenia diagnosis.
Subtypes
The DSM-5 proposal for describing schizophrenia advocates eliminating DSM-IV schizophrenia subtypes. These subtypes have limited diagnostic stability, low reliability, and poor validity. Furthermore, except for the paranoid and undifferentiated subtypes, other subtypes rarely are used in most mental health care systems.
Schizoaffective disorder
Characterizing patients with both psychotic and mood symptoms either concurrently or at different points during their illness always has been controversial. In DSM-I and DSM-II, a diagnosis of schizophrenia, schizoaffective subtype, generally was recommended for such patients. DSM-III reversed this recommendation and specified that schizophrenia was to be diagnosed only in the absence of prominent mood symptoms. Furthermore, in DSM-III, diagnosing schizoaffective disorder was strongly discouraged, and it was the only condition in DSM-III without operational criteria. Schizoaffective disorder saw a revival in DSM-III-R that has continued through DSM-IV. In fact, in many mental health care systems, almost one-third of patients with psychotic symptoms receive a schizoaffective disorder diagnosis. One of the insidious changes to the definition of schizoaffective disorder from DSM-III to DSM-IV is that it moved from being a lifetime diagnosis to a cross-sectional diagnosis—ie, in DSM-IV, only mood/psychotic symptoms in the current episode are considered, and the longitudinal course of these symptoms in the patient’s life are ignored. The current DSM-5 proposal attempts to improve reliability of this diagnosis by providing more specific criteria and is reconceptualizing schizoaffective disorder as a longitudinal diagnosis. To this end, the most significant proposed change is to criterion C of schizoaffective disorder, which attempts to demarcate schizoaffective disorder from schizophrenia with prominent mood symptoms. Criterion C will be revised to state “symptoms that meet criteria for a mood episode are present for a majority (>50%) of the total duration of the active and residual periods of the illness.”2
Psychopathological dimensions