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Brain mechanisms of social touch-induced analgesia in females.

Supportive touch has remarkable benefits in childbirth and during painful medical procedures. But does social touch influence pain neurophysiology, ie, the brain processes linked to nociception and primary pain experience? What other brain processes beyond primary pain systems mediate their analgesic effects? In this study, women (N = 30) experienced thermal pain while holding their romantic partner's hand or an inert device. Social touch reduced pain and attenuated functional magnetic resonance imaging activity in the Neurologic Pain Signature (NPS)-a multivariate brain pattern sensitive and specific to somatic pain-and increased connectivity between the NPS and both somatosensory and "default mode" regions. Brain correlates of touch-induced analgesia included reduced pain-related activation in (1) regions targeted by primary nociceptive afferents (eg, posterior insula, and anterior cingulate cortex); and (b) regions associated with affective value (orbitofrontal cortex), meaning (ventromedial prefrontal cortex [PFC]), and attentional regulation (dorsolateral PFC). Activation reductions during handholding (vs holding a rubber device) significantly mediated reductions in pain intensity and unpleasantness; greater pain reductions during handholding correlated with greater increases in emotional comfort, which correlated with higher perceived relationship quality and (a trend toward) greater perceived closeness with the romantic partner. The strongest mediators of analgesia were activity reductions in a brain circuit traditionally associated with stress and defensive behavior in mammals, including ventromedial and dorsomedial PFC, rostral anterior cingulate cortex, amygdala/hippocampus, hypothalamus, and periaqueductal gray matter. Social touch affects core brain processes that contribute to pain and pain-related affective distress in females, and should be considered alongside other treatments in medical and caregiving contexts.

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Lack of exercise induced hypoalgesia to repetitive back movement in people with chronic low back pain.

To investigate whether people with chronic low back pain (LBP) show dysfunctional exercise induced hypoalgesia (EIH) in response to repeated contractions of their back muscles during a lifting task.

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Evaluating the Psychometric Properties of the Migraine Functional Impact Questionnaire (MFIQ).

Migraine is a chronic neurologic disease that can be associated with significant migraine-related impact, disability, and burden. Patient-reported outcome measures (PRO) are included in clinical trials of migraine interventions to capture treatment effects from a patient perspective. Clinical and regulatory guidelines also encourage use of PROs in trials. The Migraine Functional Impact Questionnaire (MFIQ) is a novel PRO measure, assessing the impact of migraine on Physical Function (PF), Usual Activities (UA), Social Function (SF), and Emotional Function (EF), in the past 7 days. Scientific methods recommended to meet the requirements of the U.S. Food and Drug Administration were followed, to ensure that the MFIQ content included outcomes that were relevant to adults with migraine and were clinically relevant, specifically to evaluate preventive treatments for migraine.

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A longitudinal analysis of urologic chronic pelvic pain syndrome flares in the mapp research network.

To describe the frequency, intensity, and duration of urologic chronic pelvic pain syndrome symptom exacerbations ("flares"), as well as risk factors for these features, in the Multidisciplinary Approach to the Study of Chronic Pelvic Pain Epidemiology and Phenotyping longitudinal study.

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Clustering of Patients with Interstitial Cystitis/Bladder Pain Syndrome and Chronic Prostatitis/Chronic Pelvic Pain Syndrome.

To use clustering analysis of patient symptoms to discover common patient subtypes in females and males with interstitial cystitis/bladder pain syndrome (IC/BPS) or chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS).

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Remission From Suicidal Ideation Among Those in Chronic Pain: What Factors Are Associated With Resilience?

Although there have been many studies on the link between chronic pain and suicidality, surprisingly little research has focused on resilience and recovery among those in chronic and disabling pain who have had suicidal thoughts. The objectives of this study were to identify the prevalence and correlates of recovery from suicidal thoughts among those in chronic pain. A secondary analysis of a nationally representative sample of Canadians in chronic and disabling pain who had ever had serious suicidal thoughts (N = 635) was conducted to identify the prevalence and characteristics of those who are no longer considering suicide. Data were drawn from the Canadian Community Health Survey-Mental Health. Three in five Canadians in chronic pain (63%) who had seriously considered suicide at some point in their life had been free of these thoughts in the past year. Those free of suicidal ideation were significantly more likely to be older, women, white, better educated, with a confidant, and to use spirituality to cope, but less likely to have low household incomes, difficulties meeting basic expenses, and a history of depression and anxiety disorders. PERSPECTIVE: Almost two-thirds of formerly suicidal Canadians with chronic pain were free from suicidal thoughts in the past year. These findings provide a hopeful message of resilience and recovery in the context of disabling pain and help to improve targeted outreach to those most at risk for unremitting suicidality.

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Gender Differences in Pain Risk in Old Age: Magnitude and Contributors.

To identify the factors associated with the excess risk of pain observed among older women compared with men.

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Are there sex differences in visceral sensitivity in young healthy men and women?

Visceral hypersensitivity plays a key role in the pathophysiology of chronic visceral pain like irritable bowel syndrome (IBS), which is significantly more prevalent in women. Possible sex differences in visceral sensitivity remain poorly studied. We assessed sex differences in visceral sensitivity and their association with subclinical symptoms, trait anxiety, and chronic stress in a large sample of healthy men and women.

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Motor adaptation varies between individuals in the transition to sustained pain.

Musculoskeletal pain is associated with altered motor control that despite short-term benefit, is hypothesised to have long-term consequences, contributing to the development of chronic pain. However, data on how motor control is altered when pain is sustained beyond a transient event are scarce. Here, we investigated motor adaptation, and its relationship to corticomotor excitability, in the transition to sustained muscle pain. Twenty-eight healthy individuals were injected with nerve growth factor (NGF) into the right extensor carpi radialis brevis (ECRB) muscle on Days 0 and 2. Motor adaptation and corticomotor excitability were assessed on Day -2, prior to injection on Days 0 and 2, and again on Days 4 and 14. Motor adaptation was quantified during a radial-ulnar movement as kinematic variability of wrist flexion-extension and pronation-supination, and as electromyographic (EMG) variability of ECRB activity. Pain, muscle soreness, and functional limitation were assessed from Days 0-14. Pain, muscle soreness and functional limitation were evident at Days 2 and 4 (p<0.001). EMG variability reduced at Days 4 and 14 (p<0.04), with no change in kinematic variability (p=0.9). However, data revealed variation in EMG and kinematic variability between individuals: some displayed increased motor variability while others a decrease. Individuals who displayed an increase in EMG variability following four days of pain also displayed an increase in corticomotor excitability (r=0.43, p=0.034). These findings suggest individual adaptation of the motor system in the transition to sustained pain that could have implications for clinical musculoskeletal pain disorders.

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Associations Between Catecholaminergic and Serotonergic Genes and Persistent Arm Pain Severity Following Breast Cancer Surgery.

Persistent arm pain is a common problem following breast cancer surgery. Little is known about genetic factors that contribute to this type of postsurgical pain. Study purpose was to explore associations between persistent arm pain phenotypes and genetic polymorphisms among fifteen genes involved in catecholaminergic and serotonergic neurotransmission. Women (n=398) rated the presence and intensity of arm pain monthly for six months following breast cancer surgery. Three distinct latent classes of patients were identified (i.e., No Arm Pain (41.6%), Mild Arm Pain (23.6%), and Moderate Arm Pain (34.8%). Logistic regression analyses were used to evaluate for differences between genotype or haplotype frequencies and the persistent arm pain classes. Compared to the No Arm Pain class, three SNPs and one haplotype, in four genes, were associated with membership in the Mild Arm Pain class: COMT rs4633, HTR2A haplotype B02 (composed of rs1923886 and rs7330636), HTR3A rs1985242, and TH rs2070762. Compared to the No Arm Pain class, four SNPs in three genes were associated with membership in the Moderate Arm Pain class: COMT rs165656, HTR2A rs2770298 and rs9534511, and HTR3A rs1985242. Findings suggest that variations in catecholaminergic and serotonergic genes play a role in the development of persistent arm pain. PERSPECTIVE – Limited information is available on genetic factors that contribute to persistent arm pain following breast cancer surgery. Genetic polymorphisms in genes involved in catecholaminergic and serotonergic neurotransmission were associated with two persistent arm pain phenotypes. Findings may be used to identify patients are higher risk for this common pain condition.

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