Impaired Pain Modulation in Fibromyalgia Patients in Response to Social Distress Manipulation

Bystander Acknowledgment Mitigates the Psychological and Physiological Pain of Racial Discrimination for Black Young Adults: A Randomized Controlled Trial

Racism increases pain sensitization and contributes to racialized pain inequities; however, research has not tested interventions targeting racism to reduce pain. In this study, we examined whether White bystanders can act to mitigate racism's pain-sensitizing effects. To simulate racial exclusion in the laboratory, Black young adults (age 18-30; N = 92) were randomly assigned to be included or excluded by White players in a ball-tossing game (Cyberball). For half of the excluded participants, White bystanders acknowledged and apologized for the racial exclusion. Participants completed a cold pressor task to assess pain threshold, tolerance, and unpleasantness, and completed a survey assessing psychological needs (ie, belongingness, self-esteem, meaningful existence, and self-control). Participants who experienced racial exclusion reported significantly more threatened psychological needs and increased laboratory pain sensitization (ie, lower pain threshold and tolerance) than those who were included. However, when a White bystander acknowledged the racism, excluded participants reported higher levels of self-control, self-esteem, and decreased pain sensitization (pain threshold and tolerance) relative to excluded participants whose experience was not acknowledged. Our findings support that racism increased Black people's pain sensitivity and provide initial evidence for White bystander acknowledgment as a health intervention. PERSPECTIVE: Continual exposure to racism likely contributes to inequities in pain sensitization. We demonstrate that acute exposure to mild racism increases acute pain sensitization. Results suggest that a bystander acknowledging witnessed racism can buffer the acute sensitizing effects of racism on pain, pointing to the potential of interpersonal interventions targeting racism. TRIAL REGISTRATION: Clinicaltrials.gov NCT06113926.

Acute Ostracism-Related Pain Sensitization in the Context of Accumulated Lifetime Experiences of Ostracism

Ostracism (ie, being ignored/excluded) is a form of social adversity that powerfully impacts health and well-being. While laboratory research indicates that experimentally manipulated experiences of ostracism impact pain, findings have been mixed. Prior investigations have not considered moderating or main effects of individual histories of ostracism, and have been limited in the scope of their pain testing. In this study, participants without current pain reported lifetime experiences of ostracism prior to a laboratory visit where they were randomized to experience either a single episode of ostracism (ie, acute ostracism) or control condition that was immediately followed by quantitative sensory testing. Results indicate that the experimental effect of a single episode of ostracism on pain ratings, after-sensations, and temporal summation of pain is moderated by lifetime ostracism; no main effects were found. For individuals with histories of more lifetime ostracism, encountering a single episode of ostracism led to greater pain sensitization relative to the control condition, whereas no experimental effect was observed for individuals with little lifetime exposure to ostracism. These findings indicate that acute experiences of ostracism may be accompanied by periods of hyperalgesia for people who are chronically ostracized, implicating ostracism as a potential social moderator of pain sensitization. People who are stigmatized may therefore experience enhanced pain burden with repeated and accumulating experiences of ostracism. PERSPECTIVE: Results suggest that in the context of accumulated lifetime experiences of ostracism, single experiences of ostracism evoke central sensitization. In this way, ostracism may function to trigger central sensitization and shape socially- and societally-determined patterns of pain burden and disparity.

Lifetime ostracism experiences and mechanisms of pain

One social mechanism by which marginalization is enacted is via ostracism. Recent research has demonstrated ostracism's impact on physical health, but little is known about the relationship between accumulated lifetime experiences of ostracism and pain. Despite recent calls for added attention to social modulation of pain and social indicators of pain disparities, the impact of specific social factors on pain-including those of ostracism-are not well understood. Results of laboratory studies on the effects of acute ostracism experiences on pain sensitivity have been mixed. However, these studies have not considered lived and repeated experiences of ostracism, and primarily included single static measures of pain sensitivity. Additionally, inclusion and representation of the relationship between ostracism experiences and pain among people with minoritized identities are lacking in the current literature. In this study, we explored accumulated lifetime experiences of ostracism as a potential contributing factor to enhanced pain and one social mechanism by which societal inequity may create and maintain inequity in pain. We extracted measures of lifetime experiences of ostracism from six studies focused on social factors and (non-chronic) pain conducted between 2016 and 2020 (n = 505 adults). To retain and examine diversity within the sample, we used moderation and within-group analyses. Results indicate that greater experiences of lifetime ostracism are associated with lower cold pain tolerance, but not other pain measures, in the whole sample. Moderation and within-group analyses reveal opposing patterns of results between populations included in the extant literature (White participants, convenience samples) and those under-represented in the scientific literature (racialized groups, community samples). This study provides an example of a diversity science approach to examining social indicators of pain, illustrates the limited generalizability of previous studies on ostracism and pain, and highlights the need for increased representation and inclusion to understand mechanisms of pain and inequity.

Pelvic Pain Alters Functional Connectivity Between Anterior Cingulate Cortex and Hippocampus in Both Humans and a Rat Model

The anterior cingulate cortex (ACC) and hippocampus (HIPP) are two key brain regions associated with pain and pain-related affective processing. However, whether and how pelvic pain alters the neural activity and connectivity of the ACC and HIPP under baseline and during social pain, and the underlying cellular and molecular mechanisms, remain unclear. Using functional magnetic resonance imaging (fMRI) combined with electrophysiology and biochemistry, we show that pelvic pain, particularly, primary dysmenorrhea (PDM), causes an increase in the functional connectivity between ACC and HIPP in resting-state fMRI, and a smaller reduction in connectivity during social exclusion in PDM females with periovulatory phase. Similarly, model rats demonstrate significantly increased ACC-HIPP synchronization in the gamma band, associating with reduced modulation by ACC-theta on HIPP-gamma and increased levels of receptor proteins and excitation. This study brings together human fMRI and animal research and enables improved therapeutic strategies for ameliorating pain and pain-related affective processing.

Disrupted physical pain sensation by social exclusion in women with dysmenorrhea

Purpose

Dysmenorrhea (DM), which involves both acute and chronic pain, is associated with abnormalities in pain modulation. Previous studies have shown that social pain relies on some of the same neural regions that process physical pain, highlighting a possible physical–social pain overlap. However, evidence suggesting that social pain modulates the sensitivity to physical pain remains controversial. The present study aimed to assess the effects of social pain manipulation on sensitivity to physical pain in DM sufferers and healthy female controls (HC).

Materials and methods

Fifty-nine otherwise healthy patients with DM and 55 HC matched for age, education, calendar age, and gynecological age were randomly assigned to inclusion or exclusion conditions of Cyberball, a virtual ball tossing game used to induce social pain (social exclusion). Pain threshold and pain tolerance in response to nociceptive pressure and cold stimuli were assessed before and after the study condition.

Results

In response to cold stimulation, pain threshold and tolerance significantly reduced in DM compared to HC participants in the inclusion condition, indicating increased pain sensitivity in DM group. However, exclusion increased the pain threshold and tolerance compared to inclusion in DM but decreased pain threshold and tolerance in HC. Neither inclusion nor exclusion altered pressure pain sensitivity in DM, but, after social exclusion, DM participants were more fearful of being evaluated unfavorably. No significant differences were observed in self-esteem scores between DM and HC after both inclusion and exclusion.

Conclusion

We observed altered pain sensation in DM participants in response to social pain manipulation, suggesting that DM not only impacts menstruation but also modulates the perception of pain more generally, especially its affective processes. The present study suggests that the effect of social pain on pain sensation and certain psychometric properties depends on previous pain experience, implicating a reciprocal influence of social and physical pain processes.