Pain Inhibition Is Deficient in Chronic Widespread Pain but Normal in Major Depressive Disorder
Bibliographic record
Abstract
BACKGROUND: Given the complex relationships between fibromyalgia and major depressive disorder (MDD), it has been suggested that fibromyalgia is a "masked" MDD. In experimental settings, fibromyalgia is associated with lowered pain thresholds (hyperalgesia) and deficient pain inhibition. Similarly, it has been recently proposed that the proneness of patients with MDD to develop chronic pain results from a deficit in pain inhibition. This cross-sectional study measured experimentally induced pain perception and inhibition in patients with MDD and patients with fibromyalgia. METHOD: Participants were 29 patients with fibromyalgia (American College of Rheumatology criteria), 26 patients with MDD (DSM-IV criteria), and 40 healthy controls who did not differ in age, sex, or the presence or absence of a menstrual cycle. Data were collected between June 2007 and May 2008. Thermal stimuli were used to measure pain thresholds. Pain inhibition was elicited using a tonic thermal test (Peltier thermode) administered before and after activation of the diffuse noxious inhibitory controls (DNIC) by means of a cold pressor test. RESULTS: Thermal pain thresholds were higher in healthy controls compared to patients with MDD and patients with fibromyalgia. Pain ratings during the cold pressor test were lower in healthy controls and patients with MDD relative to patients with fibromyalgia. Finally, DNIC efficacy was stronger in healthy controls compared to patients with fibromyalgia, while no significant differences were found between healthy controls and patients with MDD. CONCLUSIONS: Our results suggest that (1) fibromyalgia and MDD are both associated with signs of hyperalgesia, (2) hyperalgesia is more pronounced in fibromyalgia, and (3) the deficit of pain inhibition is specific to fibromyalgia. As such, these results suggest that there is an overlap between fibromyalgia and MDD, but that fibromyalgia can be distinguished from MDD in terms of DNIC efficacy.
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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 | 0.015 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.003 |
| Insufficient payload (model declined to judge) | 0.001 | 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".