The journal of pain : official journal of the American Pain Society
-
An inverse association between resting blood pressure (BP) and acute pain sensitivity is well documented. Whether BP-related hypoalgesia differs by gender is unclear from prior work. Whether it increases proportionally with BP throughout the full BP range is also unknown. We examined BP-related hypoalgesia in a general population sample (n = 10,371, aged 30-87) of equal gender distribution reflecting the extremely low through hypertensive BP range. Resting BP was assessed and individuals participated in a standardized cold pressor test, providing pain ratings every 9 seconds. For systolic BP (SBP), a significant SBP × Gender interaction was observed on mean pain ratings (P < .001). Females displayed significant BP-related hypoalgesia (P < .001), with males showing a 38% smaller effect (P < .001). A similar DBP × Gender interaction was also observed (P < .05). Spline regression indicated a significant (P < .001) change in slope of the SBP-pain association at 140 mmHg. Among individuals with lower resting SBP (<140/90), increasing hypoalgesia with increasing SBP levels was observed (P < .001), with no further increases in those with higher BP (≥140/90; P > .10). This is the first large-scale study to confirm past results suggesting that BP-related hypoalgesia differs by gender; that is, females exhibited greater hypoalgesia. BP-related hypoalgesia appears subject to ceiling effects in the hypertensive BP range. ⋯ Females show greater BP-related hypoalgesia than males, highlighting gender differences in endogenous antinociceptive systems. Extent of BP-related hypoalgesia does not increase further once resting pressures reach the hypertensive range, suggesting persistent maximal demands on these antinociceptive systems among hypertensive individuals.
-
This study investigated observational learning of pain-related fear and subsequent extinction after first-hand exposure to the feared stimulus. Moreover, the specific contingencies that are learned when observing others in pain were explored. A differential fear-conditioning paradigm was used, showing video models displaying either a painful (CS+ color; aversively conditioned stimulus) or a neutral (CS- color; neutrally conditioned stimulus) facial expression in the presence of a colored warm water task (WWT; observation phase). In 1 condition (open WWT cover), the model's hand was immersed in the colored liquid, while in the other condition (closed WWT cover), no contact was displayed between the model and the liquid. During exposure, participants subsequently immersed their own hand into each WWT with equal temperatures. Results revealed successful acquisition of pain-related fear. Participants with higher levels of pain catastrophizing, intolerance of uncertainty, trait fear of pain, or dispositional empathy were more prone to develop pain-related fear. Pain-related fear extinguished quickly after direct exposure to both WWTs. Contingencies between the color of the WWT and either the painful facial expressions or the assumed properties of the colored liquid were learned in both conditions. Clinical implications and limitations of the current study are discussed, providing avenues for future research in observational learning of pain-related fear. ⋯ Pain-related fear promotes the development as well as the continuation of chronic pain. A better understanding of the acquisition and extinction of this fear may help to improve pain treatment programs. Furthermore, we intended to identify individuals who are more prone to develop pain-related fear.
-
Review Meta Analysis
Structural brain anomalies and chronic pain: a quantitative meta-analysis of gray matter volume.
The diversity of chronic pain syndromes and the methods employed to study them make integrating experimental findings challenging. This study performed coordinate-based meta-analyses using voxel-based morphometry imaging results to examine gray matter volume (GMV) differences between chronic pain patients and healthy controls. There were 12 clusters where GMV was decreased in patients compared with controls, including many regions thought to be part of the "pain matrix" of regions involved in pain perception, but also including many other regions that are not commonly regarded as pain-processing areas. The right hippocampus and parahippocampal gyrus were the only regions noted to have increased GMV in patients. Functional characterizations were implemented using the BrainMap database to determine which behavioral domains were significantly represented in these regions. The most common behavioral domains associated with these regions were cognitive, affective, and perceptual domains. Because many of these regions are not classically connected with pain and because there was such significance in functionality outside of perception, it is proposed that many of these regions are related to the constellation of comorbidities of chronic pain, such as fatigue and cognitive and emotional impairments. Further research into the mechanisms of GMV changes could provide a perspective on these findings. ⋯ Quantitative meta-analyses revealed structural differences between brains of individuals with chronic pain and healthy controls. These differences may be related to comorbidities of chronic pain.
-
This study examined the factor structure of the Children's Depression Inventory (CDI) among children and adolescents with chronic pain using exploratory and confirmatory factor analysis in a large, multisite sample of treatment-seeking youth. Participants included 1,043 children and adolescents (ages 8-18) with a range of chronic pain complaints who presented for initial evaluation at 1 of 3 tertiary care pediatric chronic pain clinics across the United States. They completed the CDI and reported on pain intensity and functional disability. Factor analysis was conducted using a 2-step (exploratory and confirmatory) approach. Results supported a 5-factor model for the CDI with good fit to the data. The distribution and item-total correlations of the somatic items (eg, pain complaints, fatigue) were explored in this sample. Results indicate that the CDI is a useful tool for assessing depressive symptoms in youth with chronic pain, but some caution is warranted in interpreting the clinical significance of scores in light of the overlap of specific symptoms common to both pain and depression. ⋯ The CDI can be considered a valid tool for assessing mood symptoms in children with chronic pain. Caution is encouraged when interpreting the clinical significance of scores due to symptom overlap between chronic pain and depression.
-
Patients and physicians report that discussions about pain are frequently frustrating and unproductive. However, the relationship between discussions about pain and patient-physician communication is poorly understood. We analyzed 133 video-recorded visits and patient self-report data collected at a clinic providing primary care to a low-income, black patient population. We used "thin slice" methods to rate two or three 30-second video segments from each visit on variables related to patient and physician affect (ie, displayed emotion) and patient-physician rapport. Discussions about pain were associated with a .32 increase in patient unease (P < .001) and a .21 increase in patient positive engagement (P = .004; standardized coefficients) compared to discussions about other topics during the same visit. Discussions about pain were not significantly associated with patient-physician rapport, physician unease, or physician positive engagement. Patient pain severity was significantly associated with greater physician and patient unease (P = .01), but not with other variables. Findings suggest that primary care patients, but not their physicians, display significantly greater emotional intensity during discussions about pain compared to discussions about other topics. ⋯ This study used direct observation of video-recorded primary care visits to show that discussions about pain are associated with heightened displays of both positive and negative patient emotions. These displays of emotion could potentially influence pain-related outcomes.