Pain perception in schizophrenia: influence of neuropeptides, cognitive disorders, and negative symptoms

Figures & data

Figure 1 Comparison of β-endorphin concentrations in test groups.

Notes: Patients with schizophrenia had about 20% (P<0.05) higher β-endorphin plasma concentrations than did healthy controls and patients’ relatives. Statistical analysis: analysis of variance rank test, Mann–Whitney test.

Figure 2 Comparison of CGRP concentrations in test groups.

Notes: Patients with schizophrenia had significantly higher (P<0.01) CGRP serum concentrations than did healthy controls and patients’ relatives. Statistical analysis: F-test analysis of variance.
Abbreviation: CGRP, calcitonin gene-related peptide.

Figure 3 The relationship between PANSS N scores and the intensity of current needed to elicit a painful stimulus in the right lower limb in patients with schizophrenia.

Note: Spearman’s rank correlation.
Abbreviation: PANSS N, Positive and Negative Syndrome Scale Negative Syndrome subscale.

Figure 4 The relationship between PANSS N scores and the intensity of current needed to elicit nociceptive reflex in the right lower limb in patients with schizophrenia.

Note: Spearman’s rank correlation.
Abbreviations: PANSS N, Positive and Negative Syndrome Scale Negative Syndrome subscale; RTIII, nociceptive reflex.

Table 1 The relationship between subjective pain threshold, nociceptive reflex, Stroop test, and TMT results in patients with schizophrenia

Parameters	N	Spearman’s rank correlation	Test value	P-value
LLL pain and Stroop test t1 [s]	12	−0.26	−0.86	>0.05
LLL pain and Stroop test t2 [s]	12	−0.60	−2.34	<0.05*
LLL pain and TMT A t3 [s]	12	−0.09	−0.30	>0.05
LLL pain and TMT B t4 [s]	12	−0.22	−0.70	>0.05
LLL RTIII and Stroop test t1 [s]	12	−0.00	−0.01	>0.05
LLL RTIII and Stroop test t2 [s]	12	−0.06	−0.19	>0.05
LLL RTIII and TMT A t3 [s]	12	0.15	0.49	>0.05
LLL RTIII and TMT B t4 [s]	12	−0.30	−1.00	>0.05
LLR pain and Stroop test t1 [s]	12	−0.78	−3.96	<0.01*
LLR pain and Stroop test t2 [s]	12	−0.62	−2.48	<0.05*
LLR pain and TMT A t3 [s]	12	−0.78	−3.88	<0.01*
LLR pain and TMT B t4 [s]	12	−0.44	−1.54	>0.05
LLR RTIII and Stroop test t1 [s]	12	−0.54	−2.01	>0.05
LLR RTIII and Stroop test t2 [s]	12	−0.37	−1.26	>0.05
LLR RTIII and TMT A t3 [s]	12	−0.61	−2.42	<0.05*
LLR RTIII and TMT B t4 [s]	12	−0.42	−1.47	>0.05

Note:

* Statistically significant.

Abbreviations: LLL pain, left lower limb subjective pain threshold; LLL RTIII, left lower limb nociceptive reflex; LLR pain, lower limb right subjective pain threshold; LLR RTIII, lower limb right nociceptive reflex; [s], time in seconds; t1, Stroop test part 1; t2, Stroop test part 2; t3, Trail-Making Test part A; t4, Trail-Making Test part B; TMT, Trail-Making Test.