Abnormalities in pain perception among individuals with depressive disorders: evidence from meta-analysis

<p indent="0mm">Depression is frequently accompanied by physical pain symptoms in clinical practice, with both conditions intertwining with each other and exacerbating the overall physical and psychological symptoms. In-depth research into pain processing in patients with depressive disorders is of great significance for the diagnosis and treatment of depressive disorders. Previous studies have shown abnormalities in pain perception among individuals with depressive disorders. Clinical evidence and surveys show that patients with depression are often more sensitive to pain and have a lower tolerance for painful experiences, suggesting a heightened to pain. Nevertheless, laboratory studies using nociceptive stimuli and psychophysical measures reveal heterogeneous results, with some studies reporting decreased sensitivity to pain (hyposensitivity), others reporting increased sensitivity (hypersensitivity), and some showing normal pain sensitivity in individuals with depression. This study employed a meta-analysis approach to systematically review experimental studies that investigated pain perception in individuals with depressive disorders. The meta-analysis was conducted following the PRISMA protocol. Studies were required to include both individuals with a diagnosed depressive disorder and a control group of healthy individuals. Moreover, studies needed to report at least one type of outcome data including pain threshold, pain tolerance, pain rating, pain unpleasantness, and sensory threshold that could be extracted for effect size calculation. Relevant studies were retrieved from databases including PubMed, Web of Science, and Elsevier by searching for keywords including [“nociception” or “pain”] and [“depressive disorder” or “mood disorder” or “depression”]. The meta-analysis was conducted in CMA 3.0, and a random effects model was used to estimate the effect size Hedges’s <italic>g</italic>. Furthermore, we examined the moderating effects of pain modality and pain site. A total of 43 studies, with a combined sample size of <italic>N</italic>=2199, were included in the meta-analysis. While no significant differences were observed in sensory thresholds between depressed patients and healthy controls (<italic>g</italic>=0.21, <italic>P</italic>=0.43), depressed patients exhibited higher pain thresholds than healthy controls (<italic>g</italic>=0.22, <italic>P</italic>=0.03), with this effect being moderated by stimulus modalities and stimulus sites. There were no significant differences in pain tolerance between the depressed patients and the control group (<italic>g</italic>=–0.04, <italic>P</italic>=0.80), although differences were observed across stimulus modalities and stimulus sites. Pain ratings (<italic>g</italic>=0.30, <italic>P</italic>=0.02) and pain unpleasantness (<italic>g</italic>=0.55, <italic>P</italic>=0.04) were found to be elevated in individuals with depression compared to healthy controls. These results demonstrate that patients with depressive disorders exhibit distinct patterns of pain perception across various outcome measures. Moreover, stimulus modality and stimulus site moderate the effect of pain perception in depression, further complicating the relationship between pain and depression. Future studies should integrate behavioral, physiological, and neuroimaging approaches to examine the mechanisms of pain processing in individuals with depression and its association with clinical variables.