Attentional bias modification for acute experimental pain: A randomized controlled trial of retraining early versus later attention on pain severity, threshold and tolerance

Understanding the Role of Expectancy, Anticipatory Anxiety, and Attention Bias in Nocebo Hyperalgesia: A Gaze-Contingent Attention Bias Modification Study

Nocebo effects in pain (nocebo hyperalgesia) have been thoroughly researched, and negative expectancies have been proposed as a key factor in causing nocebo hyperalgesia. However, little is known about the psychological mechanisms by which expectations exacerbate the perception of pain. A potential mechanism that has been proposed within wider pain research is pain-related attention. The aim of the present study was thus to explore whether attention bias (AB) to pain influenced nocebo hyperalgesia. One-hundred and thirty-four healthy participants were randomized in a 2 (AB training: towards vs away from pain) × 2 (nocebo condition: nocebo vs control) design. Pain-related AB was manipulated through a novel, partially gaze-contingent dot-probe task. Participants then completed either a nocebo instruction and conditioning paradigm or a matched control condition. Primary outcomes were measures of expectancy, anticipatory anxiety, and pain intensity completed during a nocebo test phase. Results showed that the AB manipulation was unsuccessful in inducing ABs either toward or away from pain. The nocebo paradigm induced significantly greater expectancy, anticipatory anxiety, and pain intensity for the nocebo groups compared to the control groups. In a posthoc analysis of participants with correctly induced ABs, AB towards pain amplified nocebo hyperalgesia, expectancy, and anticipatory anxiety relative to AB away from pain. The results are consistent with the expectancy model of nocebo effects and additionally identify anticipatory anxiety as an additional factor. Regarding AB, research is needed to develop reliable means to change attention sample-wide to corroborate the present findings. PERSPECTIVE: This article explores the role of AB, expectancy, and anticipatory anxiety in nocebo hyperalgesia. The study shows that expectancy can trigger anticipatory anxiety that exacerbates nocebo hyperalgesia. Further, successful AB training towards pain heightens nocebo hyperalgesia. These findings identify candidate psychological factors to target in minimizing nocebo hyperalgesia.

Spontaneous eye blinking during an auditory, an interoceptive and a visual task: The role of the sensory modality and the attentional focus

Previous evidence suggested that spontaneous eye blinking changes as a function of the attentional focus. In particular, eye blink rate (EBR) tends to increase when attention is directed to internal versus environmental processing. Most studies on this issue compared eye blinking during visual and mental imagery tasks, and interpreted the increase in EBR as a mechanism to focus cognitive resources on internal processing by disengaging attention from interfering information. However, since eye blinking also depends on the sensory modality of the task, the findings might be influenced by a modality-specific effect. In the present Registered Report we aim at investigating whether the environmental versus internal attentional focus can affect spontaneous blinking behaviour in non-visual tasks as well, in conditions where visual stimuli are not relevant. In a within-subject design, healthy participants performed an interoceptive task (i.e., heartbeat counting) and an auditory task in which pre-recorded heartbeats were presented aurally; during both tasks irrelevant visual stimuli were also presented. In a further control condition with the same auditory and visual stimuli, the participants were required to focus their attention on visual stimuli. Participants' EBR was recorded during each task by means of an eye-tracking system. We found that, although the interoceptive task was more difficult than the auditory and visual tasks, participants' EBR decreased by a comparable level in all tasks with respect to a rest condition, with no differences between internal versus environmental conditions. The present findings do not support the idea that EBR is modulated by an internal versus external focus of attention, at least in presence of controlled visual stimulation.

Development and Evaluation of Linguistic Stimuli for Pain Research

Linguistic stimuli are commonly used in research to investigate the processing of pain. To provide researchers with a dataset of pain-related and non-pain-related linguistic stimuli, this research investigated 1) the associative strength between pain-related words and the pain construct; 2) the pain-relatedness ratings of pain words; and 3) the variability in the relatedness of pain words within pain word classifications (eg, sensory pain words). In Study 1, 194 pain-related and matched non-pain-related words were retrieved by reviewing the pain-related attentional bias literature. In Study 2, adults with (n = 85) and without (n = 48) self-reported chronic pain completed a speeded word categorization paradigm and rated the pain-relatedness of a subset of pain words. Analyses revealed that 1) despite differences in associative strength of 11.3% of the words between chronic and non-chronic pain groups, no overall group difference was found, 2) the chronic pain group rated the pain words as more pain-related compared to the non-chronic pain group, and 3) there was variability in the relatedness of pain words within pain word classifications. The findings highlight the importance of validating linguistic pain stimuli. The resulting dataset is openly accessible and new published sets can be added to the Linguistic Materials for Pain (LMaP) Repository. PERSPECTIVE: This article presents the development and preliminary evaluation of a large pool of pain-related and non-pain-related words in adults with and without self-reported chronic pain. Findings are discussed and guidelines are offered to select the most suitable stimuli for future research.

Evaluating the efficacy of oxytocin for pain management: An updated systematic review and meta-analysis of randomized clinical trials and observational studies

Background

There is a need for novel analgesics with favorable risk to benefit profiles. Oxytocin has recently gained attention for its potential analgesic properties.

Aim

The aim of this study was to perform an updated systematic review and meta-analysis evaluating the effect of oxytocin for pain management.

Method

Ovid MEDLINE, Embase, PsycINFO, CINAHL, and Clinicaltrials.gov were searched for articles reporting on associations between oxytocin and chronic pain management from January 2012 to February 2022. Studies published before 2012 that were identified in our previous systematic review were also eligible. Risk of bias of included studies was assessed. Synthesis of results was performed using meta-analysis and narrative synthesis.

Results

Searches returned 2087 unique citations. In total, 14 articles were included that reported on 1504 people living with pain. Results from meta-analysis and narrative review were mixed. Meta-analysis of three studies indicated that exogenous oxytocin administration did not result in a significant reduction in pain intensity relative to placebo (N = 3; n = 95; g = 0.31; 95% confidence interval [CI] -0.10, 0.73). Narrative review provided encouraging evidence that exogenous oxytocin administration reduced pain sensitivity among individuals with back pain, abdominal pain, and migraines. Results suggested that individual difference factors (e.g., sex and chronic pain condition) may influence oxytocin-induced nociception, but the heterogeneity and limited number of studies identified precluded further investigation.

Discussion

There is equipoise for the benefit of oxytocin for pain management. Future studies are imperative and should undertake more precise exploration of potential confounds and mechanisms of analgesic action to clarify inconsistency in the literature.

Attention and interpretation cognitive bias change: A systematic review and meta-analysis of bias modification paradigms

This systematic review and meta-analysis examines the effect of Cognitive Bias Modification for attention (CBM-A) and interpretation (CBM-I) on reducing the targeted biases and investigates moderators of each approach. PsycINFO, PsychArticles, and PubMED databases were searched for randomized-controlled studies published before March 2020 with pre- and post-CBM cognitive bias outcome measures, resulting in 91 CBM-A (n = 5914 individuals) and 70 CBM-I samples (n = 4802 individuals). Random-effects models and Hedge's g calculation showed significant medium overall effects of bias reduction with moderate to high heterogeneity (CBM-A g = 0.49 [0.36, 0.64], I² = 85.19%; CBM-I g = 0.58 [0.48, 0.68], I² = 70.92%). Effect sizes did not differ between approaches and remained significant after trim-and-fill adjustment for possible publication bias. Moderator variables were investigated with meta-regression and subgroup analyses. Participant age, symptom type, control condition and number of trials moderated CBM-A; student and clinical status moderated CBM-I effect size. Results support attention and interpretation modification in controlled laboratory and variable (online) training settings for non-clinical and clinical samples across various symptom types (anxiety, depression, substance use, eating disorders). Further empirical evidence is necessary to determine optimal sample and methodological combinations most strongly associated with adaptive behavioral outcomes.

Attentional Bias Modification Training for Itch: A Proof-of-Principle Study in Healthy Individuals

Itch draws our attention to allow imposing action against bodily harm (e.g., remove insects). At the same time, itch is found to interfere with ongoing tasks and daily life goals. Despite the key role of attention in itch processing, interventions that train individuals to automatically disengage attention from itch cues are lacking. The present proof-of-principle attention bias modification (ABM) training study was aimed at investigating whether attention to itch as well as sensitivity to mild itch can be changed. Healthy volunteers were randomized over three ABM-training conditions. Training was done via a modified pictorial dot-probe task. In particular, participants were trained to look away from itch stimuli (n = 38), toward itch stimuli (n = 40) or not trained toward or away from itch at all (sham training, n = 38). The effects of the ABM-training were tested primarily on attention to itch pictures. Secondarily, it was investigated whether training effects generalized to alterations in attention to itch words and mechanical itch sensitivity. The ABM-training did not alter attention toward the itch pictures, and there was no moderation by baseline levels of attention bias for itch. Also, attention bias to the itch words and itch sensitivity were not affected by the ABM-training. This study was a first step toward trainings to change attention toward itch. Further research is warranted to optimize ABM-training methodology, for example increasing motivation of participants. Eventually, an optimized training could be used in patient populations who suffer most from distraction by their symptoms of itch.

Clinical Trial Registration: Identifier: NL6134 (NTR6273). The website URL is: https://www.trialregister.nl/

Effects of oral alcohol administration on heat pain threshold and ratings of supra-threshold stimuli

Background and aims Evidence for analgesic effects of oral alcohol consumption on heat pain has recently been documented in a placebo-controlled, randomized and double-blind design. We aimed at further investigating these effects and now set the focus on pain threshold and the ratings of supra-threshold pain to cover most of the pain range. Moreover, we now firstly evaluated sex differences in these effects. Methods We investigated 41 healthy participants (22 females) in a randomized, double-blind and placebo-controlled design and targeted two different moderate breath-alcohol levels of 0.06% and 0.08%. Before and after an alcoholic or placebo drink, contact heat was applied at the forearm. Subjects evaluated pain threshold (method of adjustment) and rated pain intensity and pain unpleasantness of supra-threshold stimuli (intensity: threshold +3 °C; duration: 5 s). Results Analgesic effects taking the form of increased pain thresholds were found after both alcohol doses, surprisingly with more pronounced effects for the lower dose. While the high alcohol dose exerted small analgesic effects on pain intensity ratings (i.e. decrease), slightly increased ratings of pain intensity and pain unpleasantness after the low alcohol dose rather suggest pain enhancement. Alcohol did not affect intensity vs. unpleasantness ratings differentially. We found no evidence for sex differences in any of these effects. Conclusions Overall, acute alcohol effects on pain were subtle. Our findings suggest that while low alcohol doses already exert analgesic effects on pain threshold, stronger doses are required for pain reduction on supra-threshold pain levels. Furthermore, sex differences could not be detected within our experimental paradigm but should be further explored in future research. Implications Analgesic effects of sub-toxic alcohol doses - as normally occurring during social drinking - might be weak; however, susceptibility to pain relieving effects of alcohol might be a risk factor for the use of alcohol as self-medication in acute pain states.

What is new in the psychology of chronic itch?

Itch is often regarded as unpleasant or bothersome and is accompanied by symptoms of distress and impairments in daily life. The biopsychosocial model of chronic itch describes how psychological factors can contribute to the improvement or exacerbation of chronic itch and related scratching behaviour. Recent research underlines the important role of cognitive-affective information processing, such as attention, affect and expectancies. This may not only play a role for acute itch states, but may particularly apply to the process of itch chronification, for example, due to the vicious cycle in which these factors shape the experience of itch. The present paper focuses on new insights into the relation between itch and the cognitive-affective factors of attention, affect and expectancies. These factors are thought to play a possible aggravating role in itch in the long term and have received increasing attention in the recent empirical literature on maintaining and exacerbating factors for chronic physical symptoms. Possible psychophysiological and neurobiological pathways regarding these factors are discussed, as well as possible intervention methods.

Differential perception of sharp pain in patients with borderline personality disorder

BACKGROUND

Cutting is the most common method of non-suicidal self-injury (NSSI) to reduce inner tension in patients with Borderline Personality Disorder (BPD). Aim of this study was to compare pain perception induced by an incision and by application of a surrogate model for sharp mechanical pain (a non-invasive "blade") in BPD.

METHODS

22 female patients and 20 healthy controls (HC) received a small incision into the volar forearm, a 7s-blade application on the same side, and non-invasive phasic stimuli (pinprick, blade, laser, tactile). Pain intensity as well as affective versus sensory components were assessed.

RESULTS

Incision was rated similarly by both groups (BPD: 28.6 ± 5.5 vs. HC: 33.9 ± 6.6; mean maximum pain ± SEM; p > 0.8), without significant difference for "7-s-blade" (BPD: 18.1 ± 3.8 vs. HC: 25.3 ± 3.6; mean maximum pain ± SEM; p > 0.17) or between "7-s-blade" and incision (BPD: p > 0.12; HC: p > 0.84). However, patients' intensity ratings returned significantly faster to baseline after incision (BPD: 38.9 ± 12.6 s vs. HC: 74.52 ± 11.5 s; p < 0.05), and patients evaluated "blade" and incision without any affective and with different sensory descriptors, indicating an altered evaluation of NSSI-like stimulation with qualitative in addition to quantitative differences-especially for the sharp pain component.

CONCLUSIONS

The reduced perception of suprathreshold nociceptive stimuli is based on a missing affective component and specific loss of the perception of "sharpness" as part of the sensory component of pain. The results further demonstrate the usefulness of the "blade" for the perception of sharpness in patients.

SIGNIFICANCE

Patients with Borderline Personality Disorder (BPD) who engage in non-suicidal self-injury (NSSI) report less pain in response to phasic nociceptive stimuli. In comparing an invasive pain stimulus to phasic nociceptive stimuli in BPD patients, the "blade" as non-invasive surrogate model for sharp mechanical pain in psychiatric patients is used. In contrast to healthy volunteers, BPD patients do not report significant affective ratings and specifically display a reduced sensory component for sharpness.

Does attention bias modification training impact on task performance in the context of pain: An experimental study in healthy participants

Attention has been theorized to play a key role in the experience of pain and associated task interference. Training attention away from pain via attention bias modification (ABM) training techniques has been proposed to improve pain-related outcomes, but evidence is inconsistent. In an experimental study, we investigated the impact of a single session ABM training -using a visual probe paradigm with idiosyncratic pain words- on cold pressor test (CPT) pain experience and task interference by pain. Fifty-eight healthy volunteers were randomly assigned to an ABM training group (N = 28; attending away from pain) and a sham training group (N = 30; no training direction). At pre-training, participants performed a baseline Random-Interval-Repetition (RIR) task and the CPT. Participants reported on sensations they experienced during the baseline CPT. Relevant descriptors were integrated in the visual probe paradigm during the training phase. At post-training, participants completed the RIR task again while experiencing CPT pain. Participants also reported on the extent they attended to the pain and the intensity/unpleasantness of the pain. Results indicated that, in contrast with our hypotheses, ABM training did also not reduce task interference due to CPT pain. Furthermore, ABM training did not change self-reported attending to CPT pain. Finally, ABM training did not reduce CPT pain intensity or pain unpleasantness. Overall, the current study provides no support for the effectiveness of a single session ABM training in improving pain-related outcomes. Future research addressing the conditions under which ABM training improves or fails to improve pain-related outcomes is warranted.

Cognitive bias modification: A review of meta-analyses

BACKGROUND

Cognitive bias modification (CBM) is a novel, but controversial intervention with considerable divergence amongst conclusions in individual studies and reviews. This systematic review synthesizes meta-analyses of CBM to determine whether CBM is effective, and what parameters most reliably evoke the process of CBM.

METHODS

A systematic literature search resulted in twelve meta-analyses in total, from which the published effect sizes were extracted.

RESULTS

Attention bias modification (ABM) shifted targeted biases in adults (ES = 0.24-1.16), was effective as a buffer to stressor vulnerability (ES = 0.33-0.77) and in symptom control (ES = 0.16-0.41). Cognitive bias modification for interpretation (CBM-I) modified targeted biases (ES = 0.52-0.81) but did not reliably reduce stressor vulnerability (ES = 0.01-0.24, p > .05). CBM consistently reduced anxiety symptoms, but effects on depressive symptomatology were less compelling. The long-term efficacy of CBM was only supported in addiction studies.

LIMITATIONS

The review included a single CBM-I only meta-analysis, and two meta-analyses with pooled reporting on ABM and CBM-I outcomes.

CONCLUSIONS

Overall, this synthesis shows CBM is effective in the short-term for anxiety in adults, and highlights some conditions under which CBM is most efficacious. Rather than debating the efficacy of CBM, future research should focus on developing procedures that more reliably induce bias modification and determining the most efficacious clinical applications.