Maintenance of affective wellbeing following acute pain in healthy older and younger adults

Heart Rate Variability and Pain: A Systematic Review

Background and Objective: Heart rate variability (HRV) as an index of the autonomic nervous system appears to be related to reactivity to experimental pain stimuli. HRV could better explain the contributions of sympathetic and parasympathetic activity response to nociceptive stimulation. The aim of this study was to systematically review and synthesize the current evidence on HRV in relation to the experience of pain in experimental tasks. Databases and Data Treatment: Studies indexed in the PubMed, PsycINFO, MEDLINE, WebOfScience, and Scopus databases were reviewed for eligibility. Studies on the autonomic response (i.e., HRV) to experimentally induced pain in healthy adults were included. Different methods of pain induction were considered (e.g., thermal, pressure, and electrical). Data were synthesized considering the association between HRV and both pain induction and subjective measures of pain. Results: Seventy-one studies were included. The results underline significant change in both the sympathetic and parasympathetic autonomic nervous systems during the painful stimulation independent of the pain induction method. The autonomic reaction to pain could be affected by several factors, such as sex, age, body mass index, breathing patterns, the intensity of the stimulation, and the affective state. Moreover, an association between the autonomic nervous system and the subjective experience of pain was found. Higher parasympathetic activity was associated with better self-regulation capacities and, accordingly, a higher pain inhibition capacity. Conclusions: HRV appears to be a helpful marker to evaluate nociceptive response in experimentally induced pain. Future studies are also needed in clinical samples to understand better the interindividual changes of autonomic response due to pain stimuli.

Cross-Sectional Associations of Fatigue Subtypes with Pain Interference in Younger, Middle-Aged, and Older Adults with Chronic Orofacial Pain

Objective

Mental, emotional, physical, and general fatigue, as well as vigor, have each been associated with pain interference—defined as pain-related disruption of social, recreational, and work-related activities—in patients with chronic orofacial pain (COFP). The objectives of the current study were to compare levels of these fatigue subtypes across younger, middle-aged, and older patients with COFP and test the associations between fatigue subtypes and pain interference in these age groups.

Design

A cross-sectional cohort design was used.

Setting

Participants self-reported fatigue subtypes (Multidimensional Fatigue Symptom Inventory–Short Form), pain interference (West Haven–Yale Multidimensional Pain Inventory), pain intensity (visual analog scale), pain duration (months), depression (Symptom Checklist 90–Revised), and sleep quality (Pittsburgh Sleep Quality Index) at their initial appointment at a tertiary orofacial pain clinic.

Subjects

Sixty younger (age 18–39), 134 middle-aged (age 40–59), and 51 older (age 60–79) COFP patients provided data for the study.

Methods

Analysis of variance was used to compare levels of fatigue subtypes between the age groups. Regression with dummy-coding was used to test if the relationship between fatigue subtypes and pain interference varied by age.

Results

Older COFP patients reported less general fatigue and more vigor than younger or middle-aged adults. Fatigue subtypes were each associated with greater pain interference, but associations became nonsignificant after controlling for depression, sleep, and pain intensity/duration. Age group–by–fatigue subtype interactions were not observed.

Conclusions

Managing fatigue may be important to reduce pain interference in COFP populations and may be accomplished in part by improving depression and sleep.

Self-regulatory ability, fatigue, and the experience of pain: Mechanistic insights from pain-free undergraduates

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.