Human Studies

To develop and examine the psychometric properties of the Treatment Expectations in Chronic Pain (TEC) scale, a brief measure of treatment expectations of chronic non-cancer pain treatment.

The purpose of this cross-sectional, descriptive study was to assess differences in neuropathic symptoms, physical and emotional well-being, and quality of life in cancer patients at the end of life compared to those without neuropathic symptoms. Neuropathic symptoms were defined as numbness and tingling in the hands and/or feet. A secondary analysis of data from two hospices in Central Florida was performed. Adults (n = 717) with a cancer diagnosis, an identified family caregiver, and who were receiving hospice services, were eligible. The prevalence of numbness/tingling in the hands or feet was 40% in this sample of hospice patients with cancer. Participants with neuropathic symptoms of numbness/tingling had a significantly higher prevalence of pain (76.7% vs. 67.0%; p = .006), difficulty with urination (29.4% vs. 20.3%; p = .007), shortness of breath (64.9% vs. 54.1%; p = .005), dizziness/lightheadedness (46.0% vs. 28.2%; p < .001), sweats (35.5% vs. 20.3%; p < .001), worrying (50.7% vs. 37.3%; p = .001), feeling irritable (38.5% vs. 28.7%; p = .008), feeling sad (48.2% vs. 37.8%; p = .008), and difficulty concentrating (46.2% vs. 32.5%; p < .001). They also reported significantly higher overall symptom intensity and symptom distress scores (p = < .001), higher pain severity (p = .001) and pain distress (p = .002), and decreased quality of life (p = .002) compared to those without numbness/tingling. Neuropathic symptoms are emotionally distressing at the end of life and associated with higher symptom burden and diminished quality of life.

Self-regulatory (SR) ability is an important resource for managing pain, but chronic pain patients experience chronic self-regulatory fatigue even when they are not in pain. Pressure pain thresholds (PPT) and pain inhibition are two mechanisms that differentiate people with and without chronic pain. It was hypothesized that trait SR ability would be associated with higher PPT and better pain inhibition and that PPT and pain inhibition would be lower following high versus low SR fatigue. Three studies tested these hypotheses. Study 1 had 240 pain-free undergraduates complete measures of trait SR ability and PPT; 122 also provided data on pain inhibition. Study 2 had 38 of Study 1's participants return for two additional sessions in which they underwent PPT testing under conditions of high or low SR fatigue (within-person, counterbalanced). Study 3 repeated these procedures with pain inhibition as the outcome (n = 39). Results revealed that individual differences in SR ability were not associated with PPT or pain inhibition (all ps > 0.05). Within people, neither PPT (F(1, 36) = 1.57, p = 0.22) nor pain inhibition (F(1, 37) = 1.79, p = 0.19) were significantly different under conditions of low versus high SR fatigue. Results do not support the hypotheses that PPT or pain inhibition associate with individual differences in trait SR ability or transient changes in state SR fatigue in the absence of pain. Instead, the SR deficits in chronic pain patients may arise from the experience of chronic pain.

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.