Hypoalgesia in schizophrenia is independent of antipsychotic drugs: A systematic quantitative review of experimental studies
Bibliographic record
Abstract
Diminished sensitivity to pain in schizophrenia has been reported since the early works of Bleuler [Bleuler E. Textbook of psychiatry (trans. Brill HA, 1951). New York: Dover Publications; 1911] and Kraepelin [Kraepelin E. Dementia praecox and paraphrenia. Edinburgh, Scotland: E and S Livingstone; 1919]. Over the last decade, experimental studies have measured pain perception in schizophrenia and produced mixed results. This meta-analysis sought to determine if the scientific literature confirms the hypothesized hypoalgesia in schizophrenia. The search was performed with computerised literature databases. A study was retained in the meta-analysis if: (i) it comprised a group of schizophrenia patients, compared to a control group of healthy volunteers; and (ii) pain was measured via experimental procedures (e.g. thermal, electrical, or mechanical stimuli). Using Comprehensive Meta-Analysis-2, effect size estimates of the differences in pain scores (all pain scores derived from all pain tests) between schizophrenia patients and healthy volunteers were calculated. Eleven studies were included in the meta-analysis. For the composite analysis, a positive, moderate, and significant effect size estimate emerged (N=497; Hedges's g=0.437; p=0.005), suggesting that patients with schizophrenia show a diminished response to experimentally-induced pain. Secondary analyses showed that: (i) drug-free patients also have hypoalgesic responses; and that (ii) sensory thresholds are increased in schizophrenia patients. This meta-analysis substantiates the hypothesis of a diminished pain response in schizophrenia. The study also suggests that hypoalgesia in schizophrenia cannot be solely explained by the effects of antipsychotic drugs, and that it may not be a pain-specific blunted response. Further studies are warranted to determine the clinical and biological correlates, and the social and health consequences, of hypoalgesia in schizophrenia.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.007 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.006 | 0.001 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".