Pain Empathy and Its Association with the Clinical Pain in Knee Osteoarthritis Patients

Analysis of the current status and factors influencing post-traumatic stress disorder in elderly patients with knee osteoarthritis: a cross-sectional study

Existing studies have focused on post-traumatic stress disorder (PTSD) after surgery in patients with knee osteoarthritis (KOA), whereas PTSD in non-operated elderly KOA patients has not been adequately studied. The aim was to assess the current status of PTSD and its influencing factors among non-surgical elderly KOA patients. From October to November 2021, a cross-sectional study was conducted among 320 consecutive patients aged ≥ 65 years with radiologically confirmed KOA and no history of knee surgery or psychiatric disorders, recruited from three community hospitals in Changsha, Hunan Province. A total of 314 participants completed validated assessments for PTSD (PTSD Checklist-Civilian Version), pain (Numerical Rating Scale), anxiety (Generalized Anxiety Disorder Scale), depression (Patient Health Questionnaire-9), and social support (Social Support Rating Scale). Data were analyzed using non-parametric tests and Spearman correlation. Structural equation modeling (SEM) was performed with Amos 24.0, employing maximum likelihood estimation and 1000 bootstrap samples to test mediation effects. Among 314 analyzed participants (mean age 72.91 ± 6.384 years; 60.80% female and 39.20% males), PTSD prevalence was 18.20%. Significantly higher PTSD risk was associated with low education levels (Z=-2.398, P = 0.016), low salaries (H = -2.398, P = 0.005), unemployed patients (H = 10.030, P = 0.007), no exercise (H = 9.328, P = 0.025), smoking (Z = -2.504, P = 0.012) and no leisure activities (Z=-2.074, P = 0.038). Structural equation modeling revealed a direct effect of depression on PTSD with the path coefficient of 0.701 (95% CI 0.518-0.879, P = 0.001) and an indirect effect of pain on PTSD through social support with the path coefficient of -0.014 (95% CI -0.049 to -0.001, P = 0.035 < 0.05). Non-surgical elderly patients with knee osteoarthritis exhibit clinically significant post-traumatic stress disorder rates (18.20%), primarily driven by depression and mediated through pain-social support pathways. These findings underscore the need for integrated biopsychosocial interventions targeting pain management, mental health screening, and social support enhancement in this population.

Neural circuits and therapeutic mechanisms of empathic pain

Empathy is the capacity to understand and share the experiences of others. This ability fosters connections between individuals, enriching the fabric of our shared world. One notable example is empathy for the pain of others. Such experiences facilitate the identification of potential dangers, both for oneself and for others. Neuroimaging studies have helped to pinpoint brain regions that modulate empathic pain. Recently, there has also been a surge in studies exploring the neural mechanisms of empathic pain in rodent models. Neuropsychiatric disorders such as autism, psychosis, and schizophrenia often exhibit empathy deficits. Targeting the modulation of empathic pain holds potential for alleviating core symptoms in these patients. Interestingly, empathy research may also benefit pain management, leading to new approaches for understanding the negative emotions associated with pain. This review summarizes recent advances in neuroimaging for the study of empathic pain, outlines the underlying neurocircuit mechanisms, describes therapeutic strategies, and explores promising avenues for future research. This article is part of the Special Issue on "Empathic Pain".

The validation and cross-cultural adaptation of the PainDETECT questionnaire in osteoarthritis-related pain

BACKGROUND

Patients with knee osteoarthritis (KOA) often experience persistent pain and functional impairment after total knee arthroplasty (TKA), which presents challenges for pain management. Accurate preoperative assessment of pain characteristics is crucial for tailoring individualized treatment plans. The PainDETECT Questionnaire has been widely used to identify neuropathic components in chronic pain and has been validated for its reliability and validity across various cultural contexts. However, a culturally adapted version tailored to Chinese patients is currently lacking. This study aims to translate and culturally adapt PainDETECT for Chinese patients and evaluate its validity in TKA patients in China.

METHODS

This study followed international guidelines to translate and adapt the PainDETECT Questionnaire (PDQ) into Chinese (PDQ-CV). A cohort of 241 knee osteoarthritis (KOA) patients completed the PDQ-CV, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), EuroQol-5 Dimensions-5 Levels (EQ-5D-5 L), and Central Sensitization Inventory Chinese Version (CSI-CV). We assessed internal consistency using Cronbach's alpha and test-retest reliability via intraclass correlation coefficient (ICC). Construct and structural validity were evaluated through Pearson correlations and factor analyses.

RESULTS

The PDQ-CV demonstrated good acceptability among KOA patients, with no floor or ceiling effects observed. Internal consistency was high (Cronbach's α = 0.896), and test-retest reliability was excellent (ICC = 0.994; 95% CI: 0.943-1.045). The PDQ-CV total score showed significant positive correlations with WOMAC (r = 0.589, P < 0.01), EQ-5D-5 L (r = 0.533, P < 0.01), and CSI-CV (r = 0.776, P < 0.01). Exploratory factor analysis (EFA) extracted two primary factors, corresponding to the sensory dimension (52.1% variance) and the affective dimension (16.3% variance), explaining a total variance of 68.4%.

CONCLUSION

The PDQ-CV demonstrated good feasibility, reliability, and validity in Chinese KOA patients, supporting its use in clinical practice and providing a foundation for future research.

Nearsighted empathy: exploring the effect of empathy on distance perception, with eye movements as modulators

Empathy, a cornerstone of social interaction, involves shared representation, eliciting vicarious emotions. However, its influence on shared perceptual representations, particularly in foundational domains such as distance perception, remains unexplored. In this study, we introduce a novel adaptation of the empathy for pain task to investigate empathy's influence on distance perception. We also examine how two personality traits, trait empathy and alexithymia, modulate this relationship. Utilizing eye-tracking technology, we examine how attention allocation to different facial and bodily features affects empathy's impact on distance perception. Our findings indicate that empathy biases individuals to perceive targets as closer, with trait empathy reinforcing this effect and alexithymia attenuating it. Furthermore, we demonstrate that heightened attention to eyes and face correlates with perceiving targets as closer, while attention to hand shows the opposite trend. These results underscore the broader influence of empathy beyond shared emotions, revealing its capacity to alter perceptual processes. By elucidating the interplay between personality traits and visual inputs in shaping these alterations, our study offers valuable insights for future research exploring the role of shared representation in empathy across various perceptual domains.

Pain catastrophizing in rheumatic diseases: prevalence, origin, and implications

Pain is a crucial factor in rheumatic disorders, and reducing it is a primary goal of successful treatment. Adaptive pain-coping strategies can enhance this improvement, but maladaptive approaches such as pain catastrophizing may worsen overall patient well-being. This narrative review aims to provide a concise overview of the existing knowledge on pain catastrophizing in the most prevalent specific rheumatic disorders. The objective of this study was to improve understanding of this phenomenon and its implications, as well as to pinpoint potential directions for future research. We conducted searches in the MEDLINE/PubMed, SCOPUS, and DOAJ bibliography databases to identify articles related to pain catastrophizing in rheumatoid arthritis, psoriatic arthritis, axial spondylarthritis, systemic sclerosis, systemic lupus erythematosus, Sjögren's syndrome, juvenile idiopathic arthritis, and osteoarthritis (non-surgical treatment). Data extraction was performed on November 1, 2023. The investigators screened the identified articles to determine their relevance and whether they met the inclusion criteria. Following a bibliography search, which was further expanded by screening of citations and references, we included 156 records in the current review. The full-text analysis centred on pain catastrophizing, encompassing its prevalence, pathogenesis, and impact. The review established the role of catastrophizing in amplifying pain and diminishing various aspects of general well-being. Also, potential treatment approaches were discussed and summarised across the examined disorders. Pain catastrophizing is as a significant factor in rheumatic disorders. Its impact warrants further exploration through prospective controlled trials to enhance global patient outcomes.

Pain experience reduces social avoidance to others in pain: a c-Fos-based functional connectivity network study in mice

Pain experience increases individuals' perception and contagion of others' pain, but whether pain experience affects individuals' affiliative or antagonistic responses to others' pain is largely unknown. Additionally, the neural mechanisms underlying how pain experience modulates individuals' responses to others' pain remain unclear. In this study, we explored the effects of pain experience on individuals' responses to others' pain and the underlying neural mechanisms. By comparing locomotion, social, exploration, stereotyped, and anxiety-like behaviors of mice without any pain experience (naïve observers) and mice with a similar pain experience (experienced observers) when they observed the pain-free demonstrator with intraperitoneal injection of normal saline and the painful demonstrator with intraperitoneal injection of acetic acid, we found that pain experience of the observers led to decreased social avoidance to the painful demonstrator. Through whole-brain c-Fos quantification, we discovered that pain experience altered neuronal activity and enhanced functional connectivity in the mouse brain. The analysis of complex network and graph theory exhibited that functional connectivity networks and activated hub regions were altered by pain experience. Together, these findings reveal that neuronal activity and functional connectivity networks are involved in the modulation of individuals' responses to others' pain by pain experience.

Limbic system plasticity after electroacupuncture intervention in knee osteoarthritis rats

Knee osteoarthritis (KOA) is characterized by debilitating pain. Electroacupuncture (EA), a traditional Chinese medical therapy, has shown promise in KOA pain management. This study investigated the therapeutic potential of EA in KOA and its impact on limbic system neural plasticity. Sixteen rats were randomly assigned into two groups: EA group and sham-EA group. EA or sham-EA interventions were administered at acupoints ST32 (Futu) and ST36 (Zusanli) for three weeks. Post-intervention resting-state fMRI was scanned, assessing parameters including Amplitude of low frequency fluctuations (ALFF), regional homogeneity (ReHo), functional connectivity (FC) and nodal characterizations of network within limbic system. The results showed that EA was strategically directed towards the limbic system, resulting in discernible alterations in neural activity, FC, and network characteristics. Our findings demonstrate that EA had a significant impact on the limbic system neural plasticity in rats with KOA, presenting a novel nonpharmacological approach for KOA treatment.

Relationship between individual differences in pain empathy and task- and resting-state EEG

Pain empathy is a complex form of psychological inference that enables us to understand how others feel in the context of pain. Since pain empathy may be grounded in our own pain experiences, it exhibits huge inter-individual variability. However, the neural mechanisms behind the individual differences in pain empathy and its association with pain perception are still poorly understood. In this study, we aimed to characterize brain mechanisms associated with individual differences in pain empathy in adult participants (n = 24). The 32-channel electroencephalography (EEG) was recorded at rest and during a pain empathy task, and participants viewed static visual stimuli of the limbs submitted to painful and nonpainful stimulation to solicit empathy. The pain sensitivity of each participant was measured using a series of direct current stimulations. In our results, the N2 of Fz and the LPP of P3 and P4 were affected by painful pictures. We found that both delta and alpha bands in the frontal and parietal cortex were involved in the regulation of pain empathy. For the delta band, a close relationship was found between average power, either in the resting or task state, and individual differences in pain empathy. It suggested that the spectral power in Fz's delta band may reflect subjective pain empathy across individuals. For the alpha band, the functional connectivity between Fz and P3 under painful picture stimulation was correlated to individuals' pain sensitivity. It indicated that the alpha band may reflect individual differences in pain sensitivity and be involved in pain empathy processing. Our results suggested the distinct role of the delta and alpha bands of EEG signals in pain empathy processing and may deepen our understanding of the neural mechanisms underpinning pain empathy.

Validation of the Chinese version of the Brief Pain Inventory in patients with knee osteoarthritis

BACKGROUND

Knee osteoarthritis (KOA) primarily presents with symptoms of pain and compromised functionality. Pain is a subjective manifestation that necessitates the employment of reliable evaluation tools for practical assessment, thereby enabling the formulation of appropriate interventional strategies. The Brief Pain Inventory (BPI) is a widely utilized questionnaire for evaluating the status of chronic pain. The purpose of the present study is to translate the short form of BPI into Chinese version (BPI-CV) and conduct cross-cultural adaptation to evaluate the psychometric characteristics of BPI-CV in KOA patients.

METHODS

BPI-CV was translated and cross-culturally adapted according to internationally recognized guidelines. A cohort comprising 150 patients diagnosed with KOA successfully completed the demographic questionnaire, BPI-CV, Western Ontario and McMaster University Osteoarthritis Index (WOMAC), and the EuroQoL Group's five-dimension questionnaire (EQ-5D). Internal consistency and test-retest analysis were used to evaluate the reliability. The internal consistency of the scale items was evaluated by calculating the Cronbach's α value (> 0.7). We chose to employ two scales commonly used in the evaluation of KOA patients: the disease-specific WOMAC scale and the universal EQ-5D scale. Construct validity was determined through Pearson correlation analysis, comparing BPI scores with those obtained from the WOMAC and EQ-5D scales. Exploratory factor analysis was used to structural validity.

RESULTS

The BPI-CV was well accepted with no ceiling or floor effect. Cronbach's α for assessing internal consistency was 0.894. Test-retest reliability was excellent with an ICC of 0.852 (95%CI 0.785-0.905). The BPI-CV showed moderate to strong correlations with the pain dimension (r = 0.496-0.860) and the functional interference dimension (r = 0.517-0.712) of the WOMAC and the EQ-5D (r = 0.527-0.743). Three factors resulted using exploratory factor analysis: pain severity, activity interference, and emotional interference, accounting for 79.0% of the total variance. Standard error of measurement was 0.539.

CONCLUSION

BPI-CV has good feasibility, reliability, and validity. It can be recommended for KOA patients in mainland China.