Pain
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Facial expressions during infancy are important to examine, as infants do not have the language skills to describe their experiences. This is particularly vital in the context of pain, where infants depend solely on their caregivers for relief. The objective of the current study was to investigate the development of negative infant facial expressions in response to immunization pain over the first year of life. ⋯ Instead, infants displayed a variety of generalized pain and distress faces aimed at gaining caregiver aid. The development of nonverbal communication in infants, particularly facial expressions, remains an important area of inquiry. Further study into accurately measuring infant negative emotions, pain, and distress is warranted.
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Psychological factors are thought to play a part in the aetiology of chronic widespread pain. We investigated the relationship between intelligence in childhood and risk of chronic widespread pain in adulthood in 6902 men and women from the National Child Development Survey (1958 British Birth Cohort). Participants took a test of general cognitive ability at age 11 years; and chronic widespread pain, defined according to the American College of Rheumatology criteria, was assessed at age 45 years. ⋯ In multivariate backwards stepwise regression, lower childhood intelligence remained as an independent predictor of chronic widespread pain (RR 1.10; 95% CI 1.01-1.19), along with social class, educational attainment, body mass index, smoking status, and psychological distress. Part of the effect of lower childhood intelligence on risk of chronic widespread pain in midlife was significantly mediated through greater body mass index and more disadvantaged socioeconomic position. Men and women with higher intelligence in childhood are less likely as adults to report chronic widespread pain.
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Randomized Controlled Trial
Brain networks predicting placebo analgesia in a clinical trial for chronic back pain.
A fundamental question for placebo research is whether such responses are a predisposition, quantifiable by brain characteristics. We examine this issue in chronic back pain (CBP) patients who participated in a double-blind brain imaging (functional magnetic resonance imaging) clinical trial. We recently reported that when the 30 CBP participants were treated, for 2 weeks, with topical analgesic or no drug patches, pain and brain activity decreased independently of treatment type and thus were attributed to placebo responses. ⋯ Additionally, by means of frequency domain contrasts, we observe that at baseline, left dorsolateral prefrontal cortex high-frequency oscillations also predicted treatment outcomes and identified an additional set of functional connections distinguishing treatment outcomes. Combining medial and lateral prefrontal functional connections, we observe a statistically higher accuracy (0.9) for predicting posttreatment groups. These findings indicate that placebo response can be identified a priori at least in CBP, and that neuronal population interactions between prefrontal cognitive and pain processing regions predetermine the probability of placebo response in the clinical setting.
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Multicenter Study
Predictors for postpartum pelvic girdle pain in working women: the Mom@Work cohort study.
The objective of this study was to examine which factors during pregnancy and postpartum predict pelvic girdle pain (PGP) at 12 weeks postpartum among working women. A total of 548 Dutch pregnant employees were recruited in 15 companies, mainly health care, child care, and supermarkets. The definition of PGP was any pain felt in the pelvic girdle region at 12 weeks postpartum. ⋯ The pregnancy and postpartum-related predictors were: more disability at 6 weeks, having PGP at 6 weeks, higher mean pain at 6 weeks, higher somatisation during pregnancy and at 6 weeks postpartum, higher birth weight of the baby, uncomfortable postures at work and number of days of bed rest. Based on these results, it is concluded that extra attention should be given to women who experience PGP during pregnancy to prevent serious PGP during late pregnancy and postpartum. More research is needed to confirm the roles of hours of sleep, somatisation, and bed rest in relation to PGP.
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Randomized Controlled Trial
The hidden effects of blinded, placebo-controlled randomized trials: an experimental investigation.
The knowledge of having only a 50% chance of receiving an active drug can result in reduced efficacy in blinded randomized clinical trials (RCTs) compared to clinical practice (reduced external validity). Moreover, minor onset sensations associated with the drug (but not with an inert placebo) can further challenge the attribution of group differences to drug-specific efficacy (internal validity). We used a randomized experimental study with inert placebos (inert substance) vs active placebos (inducing minor sensations), and different instructions about group allocation (probability of receiving drug: 0%, 50%, 100%). ⋯ Moreover, minor drug onset sensations can challenge internal validity. Effect sizes for these mechanisms are medium, and can substantially compete with specific drug effects. For clinical trials, new study designs are needed that better control for these effects.