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Different pain types may be encoded in different brain circuits. Here, we examine similarities and differences in brain processing of visceral and somatic pain. We analyze data from seven fMRI studies (N = 165) and five types of pain and discomfort (esophageal, gastric, and rectal distension, cutaneous thermal stimulation, and vulvar pressure) to establish and validate generalizable pain representations. We first evaluate an established multivariate brain measure, the Neurologic Pain Signature (NPS), as a common nociceptive pain system across pain types. Then, we develop a multivariate classifier to distinguish visceral from somatic pain. The NPS responds robustly in 98% of participants across pain types, correlates with perceived intensity of visceral pain and discomfort, and shows specificity to pain when compared with cognitive and affective conditions from twelve additional studies (N = 180). Pre-defined signatures for non-pain negative affect do not respond to visceral pain. The visceral versus the somatic classifier reliably distinguishes somatic (thermal) from visceral (rectal) stimulation in both cross-validation and independent cohorts. Other pain types reflect mixtures of somatic and visceral patterns. These results validate the NPS as measuring a common core nociceptive pain system across pain types, and provide a new classifier for visceral versus somatic pain.
Learn More >The aim of this study was to examine the association between the length of time between an emergency department (ED) visit and the subsequent initiation of physical therapist intervention for low back pain (LBP) on 1-year LBP-related health care utilization (ie, surgery, advanced imaging, injections, long-term opioid use, ED visits) and costs.
Learn More >To characterize psychologic functioning across five chronic overlapping pain conditions (COPCs)-temporomandibular disorders, fibromyalgia, low back pain, headache, and irritable bowel syndrome-and their overlaps.
Learn More >This report examines the association between tetrahydrocannabinol (THC) plasma levels and pain response in a secondary analysis of data from a recent diabetic neuropathy study that demonstrated a dose-dependent reduction in spontaneous and elicited pain at specific time points. A randomized, double-blinded, placebo-controlled crossover study was conducted in sixteen patients with painful diabetic peripheral neuropathy. Subjects participated in four sessions, separated by 2 weeks, during each of which they were exposed to one of four conditions: placebo, or 1%, 4%, or 7% THC dose of cannabis. Baseline assessments of spontaneous and evoked pain were performed. Subjects were then administered aerosolized cannabis or placebo and pain intensity and cognitive testing at specific time points for 4 hours. A blood sample was drawn from the left antecubital vein for plasma assay of total THC at 0, 15, 30, 45, 60, 150, and 240 minutes. Associations were made between pain intensity, cognitive impairment and THC plasma levels in this secondary analysis. Results suggested a U-shaped relation whereby pain ratings are greatest at extreme (low and high) levels of THC. The therapeutic window appeared to fall between 16 ng/mL and 31 ng/mL THC plasma level. There was a significant linear effect of THC on only one out of the three cognitive tests. These findings stress the importance of measuring cannabinoid plasma levels when performing future research. Perspective: This analysis correlating plasma THC levels and pain reduction in diabetic neuropathy suggest a therapeutic window. Low and high THC levels had a negative association (no reduction) and THC levels within the window had a positive association (reduction). There was a minor negative linear effect of THC on cognitive function.
Learn More >Changing Behavior through Physical Therapy (CBPT), a cognitive-behavioral-based program, has been shown to improve outcomes after lumbar spine surgery in patients with a high psychosocial risk profile; however, little is known about potential mechanisms associated with CBPT treatment effects. The purpose of this study was to explore potential mediators underlying CBPT efficacy after spine surgery.
Learn More >Among 170 adults with sickle cell disease, we evaluated chronic pain impact and disability prevalence, assessed age and gender differences, and identified psychosocial predictors of chronic pain intensity and disability. Most participants had a high level of disability. Chronic pain intensity and disability were significantly associated with pain catastrophizing and chronic pain self-efficacy, and worsened with age. Further research is needed to confirm study findings and develop interventions, including palliative care approaches that address catastrophizing and disability, particularly for young women and middle-aged adults with sickle cell disease. Moreover, consistent clinical assessment of chronic pain and psychosocial health should be implemented.
Learn More >Telomere length, a measure of cellular aging, is inversely associated with chronic pain severity. While psychological resilience factors (e.g., optimism, acceptance, positive affect, active coping) are associated with lower levels of clinical pain and greater physical functioning, it is unknown whether resilience may buffer against telomere shortening in individuals with chronic pain. Additionally, a broader conceptualization of resilience that includes social and biobehavioral factors may improve our understanding of the relationship between resilience, chronic pain, and health outcomes. In individuals with and without chronic knee pain, we investigated whether: 1) psychological resilience would be positively associated with telomere length, and if 2) a broader conceptualization of resilience including social and biobehavioral factors would strengthen the association. Seventy-nine adults, 45-85 years of age, with and without knee pain completed demographic, health, clinical pain, psychological, social, and biobehavioral questionnaires. Resilience levels were determining by summing the total number of measures indicating resilience based on published clinical ranges and norms. Blood samples were collected and telomere length determined. In regression analyses controlling for sex, race, age, and characteristic pain intensity, greater psychological resilience and psychosocial/biobehavioral resilience were associated with longer telomeres (p = .0295 and p = .0116, respectively). When compared, psychosocial/biobehavioral resilience was significantly more predictive of telomere length than the psychological resilience (p < .0001). Findings are promising and encourage further investigations to enhance understanding of the biological interface of psychosocial and biobehavioral resilience factors in individuals with musculoskeletal chronic pain conditions.
Learn More >Rare pain-insensitive individuals offer unique insights into how pain circuits function and have led to the development of new strategies for pain control. We investigated pain sensitivity in humans with WAGR (Wilms tumor, aniridia, genitourinary anomaly, and range of intellectual disabilities) syndrome, who have variably sized heterozygous deletion of the 11p13 region. The deletion region can be inclusive or exclusive of the brain-derived neurotrophic factor (BDNF) gene, a crucial trophic factor for nociceptive afferents. Nociceptive responses assessed by quantitative sensory testing demonstrated reduced pain sensitivity only in the WAGR subjects whose deletion boundaries included the BDNF gene. Corresponding behavioral assessments were made in heterozygous Bdnf knockout rats to examine the specific role of Bdnf. These analogous experiments revealed impairment of Aδ- and C-fiber-mediated heat nociception, determined by acute nociceptive thermal stimuli, and in aversive behaviors evoked when the rats were placed on a hot plate. Similar results were obtained for C-fiber-mediated cold responses and cold avoidance on a cold-plate device. Together, these results suggested a blunted responsiveness to aversive stimuli. Our parallel observations in humans and rats show that hemizygous deletion of the BDNF gene reduces pain sensitivity and establishes BDNF as a determinant of nociceptive sensitivity.
Learn More >Persistent pain (PP) and long-term conditions are all associated with psychological well-being. Less is known about their associations with reduced psychological well-being when co-occurring. We investigated how PP and long-term physical and mental conditions relate to psychological well-being when occurring together.
Learn More >Pain serves vital protective functions, which crucially depend on appropriate motor responses to noxious stimuli. Such responses not only depend on but can themselves shape the perception of pain. In chronic pain, perception is often decoupled from noxious stimuli and motor responses are no longer protective, which suggests that the relationships between noxious stimuli, pain perception, and behavior might be changed. We here performed a simple experiment to quantitatively assess the relationships between noxious stimuli, perception and behavior in 22 chronic pain patients and 22 age-matched healthy human participants. Brief noxious and tactile stimuli were applied to the participants' hands and participants performed speeded motor responses and provided perceptual ratings of the stimuli. Multi-level moderated mediation analyses assessed the relationships between stimulus intensity, perceptual ratings and reaction times for both stimulus types. The results revealed a significantly stronger involvement of motor responses in the translation of noxious stimuli into perception than in the translation of tactile stimuli into perception. This significant influence of motor responses on pain perception was found for both chronic pain patients and healthy participants. Thus, stimulus-perception-behavior relationships appear to be at least partially preserved in chronic pain patients and motor-related as well as behavioral interventions might harness these functional relationships to modulate pain perception.
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