Table 1.
Main research implications of HiTOP reconceptualization of schizophrenia.
| Research considerations | Traditional diagnosis | HiTOP model |
|---|---|---|
| Schizophrenia concept | A distinct group of patients | Arbitrary designation for patients elevated above a threshold on two fundamental spectra |
| Role of psychotic symptoms | Necessary diagnostic feature | Not necessary, an extreme end of just one dimension |
| Etiology and pathophysiology | Implied to be largely discrete and specific to schizophrenia | Discrete and specific mechanisms are expected to be rare. The majority of mechanisms are expected to be present across the general population and implicated in many disorders |
| Expectations for case-control study design | Can efficiently isolate common features of schizophrenia group | Is not representative, as it excludes people who are (a) not clear cases or controls and (b) cases with significant comorbidities. Is biased as cases recruited from treatment settings differ from controls on many irrelevant features (intelligence, distress, medication exposure, etc) |
| Optimal design | Case-control with strict inclusion/exclusion criteria | Inclusive population-based studies (perhaps enriched for high scores on spectra) with detailed phenotyping allowing to determine which effects are specific to psychopathology of interest and which are general |
| Participant selection | Definite cases but optimally antipsychotic-naïve or washed out from medications | Moderate severity of psychoticism and detachment (e.g., maladaptive traits) is acceptable. Such people are far more common and usually had no prior treatment. |
| Measurement | Differential diagnosis to separate schizophrenia cases from related disorders (e.g., semi-structured diagnostic interview) | Core description is 2 spectra, which can be elaborate as scores on 14 subdimensions. It covers traits and symptoms. Other HiTOP spectra can be assessed to obtain comprehensive profile. Various interviews, self-report, and informant-report tools are available |
| Scalability | Diagnostic interview is required, low scalability | Brief self-reports can be collected online in large samples and confirmed by interview in subsamples |