Decreased Pain Sensitivity Among People with Schizophrenia: A Meta-analysis of Experimental Pain Induction Studies

anon79999497 · July 25, 2015, 12:07pm

ncbi.nlm.nih.gov

Decreased pain sensitivity among people with schizophrenia: a meta-analysis of experimental pain induction studies.

B Stubbs, T Thompson, S Acaster, D Vancampfort, F Gaughran and CU Correll, Pain, Nov 2015

Patients with schizophrenia report reduced pain sensitivity in clinical studies, but experimental studies are required to establish pain sensitivity as a potential endophenotype. We conducted a systematic review of electronic databases from database inception until April 15, 2015, including experimental studies investigating pain among patients with schizophrenia spectrum disorder vs healthy controls. A random-effect meta-analysis yielding Hedges' g ±95% confidence intervals (CIs) as the effect size (ES) measure was conducted. Primary outcome was a pooled composite of pain threshold and pain tolerance; secondary outcomes included these parameters individually, plus sensory threshold, physiological pain response, and pain intensity or unpleasantness. Across 17 studies, patients with schizophrenia spectrum disorder (n = 387; age, 30.7 ± 6.9 years; females, 31.9%; illness duration, 7.0 ± 5.7 years) were compared with controls (n = 483; age, 29.5 ± 7.4 years; females, 31.0%). Patients had elevated pain threshold/pain tolerance vs controls (ES = 0.583; 95% CI, 0.212-0.954; P = 0.002; studies = 15). Results were similar in antipsychotic-free individuals (ES = 0.599; 95% CI, 0.291-0.907; P < 0.0001; studies = 8), with trend-level significance in antipsychotic-treated individuals (ES = 0.566; 95% CI, -0.007 to 1.125; P = 0.047; studies = 9). Likewise, patients with schizophrenia had increased pain tolerance (ES = 0.566; 95% CI, 0.235-0.897; P = 0.0001; studies = 6), sensory threshold (ES = 1.16; 95% CI, 0.505-1.727; P < 0.0001; studies = 5), and pain threshold (ES = 0.696; 95% CI, 0.407-0.986; P < 0.001; studies = 9), as well as reduced physiological response to noxious stimuli (ES = 0.456; 95% CI, 0.131-0.783; P = 0.006) and pain intensity/unpleasantness ratings (ES = 0.547; 95% CI, 0.146-0.949; P = 0.008). Findings were similarly significant in antipsychotic-free patients with schizophrenia (analysable parameters = 4) and antipsychotic-treated individuals (analysable parameters = 2). Finally, greater psychiatric symptoms moderated increased pain threshold, and younger patient age moderated increased pain tolerance. Decreased pain sensitivity seems to be an endophenotype of schizophrenia spectrum disorders. How this alteration links to other dimensions of schizophrenia and physical comorbidity-related help-seeking behaviour/morbidity/mortality requires further study.

Username · July 25, 2015, 12:10pm

And this proves what - I wish they would spend funding on medication rather than pain thresholds. Maybe I’m being ignorant?

anon79999497 · July 25, 2015, 12:32pm

I would be concerned if patients were forced into these studies but I am guessing they were voluntary participants and could say no at any point.
If they weren’t then I agree such research could be seen as unethical.

metime · July 26, 2015, 10:48pm

I didn’t consider that. Good point!

Csummers · July 26, 2015, 11:03pm

Meds can only do so much.
I have been called “VERY pain tolerant” by my dentist, Dr., and one rogue cop.

When others take pleasure in serving up pain,
It just becomes one more side effect I’ve learned to ignore.

anon79999497 · July 26, 2015, 11:13pm

This earlier research is more ambivalent.

CONCLUSION:

Results indicate that schizophrenic subjects present a specific experimental pain response profile, characterized by elevated sensitivity to acute pain but reduced sensitivity to prolonged pain.

ncbi.nlm.nih.gov

Pain perception in schizophrenia: evidence of a specific pain response profile.

M Lévesque, S Potvin, S Marchand, E Stip, S Grignon, L Pierre, O Lipp and P Goffaux, Pain medicine (Malden, Mass.), Dec 2012

Ever since the characterization of schizophrenia, clinicians have noted abnormal pain sensitivity in their patients. The published literature, however, is inconsistent concerning the nature of the change reported. The objective of this study was to characterize the pain response profile of schizophrenic patients by providing both acute and prolonged (i.e., rapidly repeating) painful stimuli to schizophrenic participants and control subjects.Twelve schizophrenic subjects and eleven controls were included in the final analysis. Diagnosis was made according to Diagnostic and Statistical Manual of mental disorders-4th edition, text revision (DSM-IV-TR) criteria.Intermittent, transcutaneous stimulations of the left sural nerve were administered to all participants. Painful sural nerve stimulations provoked a nociceptive flexion reflex response which was measured using an electromyographic recording of the bicep femoris muscle. Pain ratings were obtained using a 0-10 verbal numerical scale. Among schizophrenic participants, the relationship between subjective pain, reflex amplitude, and clinical features was investigated. The Positive and Negative Syndrome Scale, Calgary Depression Scale for Schizophrenia, and Subjective Scale to Investigate Cognition in Schizophrenia were used to evaluate clinical features.Compared with controls, schizophrenic subjects showed increased sensitivity to acute pain (i.e., lower pain thresholds; P = 0.019), but decreased subjective pain sensitization (P = 0.027). Group differences in subjective pain sensitization were not accompanied by group differences in nociceptive reflex activity (P = 0.260), suggesting supraspinal origins to the change in pain experienced by schizophrenic subjects. Moreover, positive symptoms correlated negatively with pain threshold values among schizophrenic participants (r = -0.696, P = 0.012), suggesting that distortions of thought and function relate to pain sensitivity in schizophrenic patients.Results indicate that schizophrenic subjects present a specific experimental pain response profile, characterized by elevated sensitivity to acute pain but reduced sensitivity to prolonged pain.