Attentional bias towards pain-related information in chronic pain; a meta-analysis of visual-probe investigations

The Role of Psychosocial Processes in the Development and Maintenance of Chronic Pain

The recently proposed Analgesic, Anesthetic, and Addiction Clinical Trial Translations, Innovations, Opportunities, and Networks (ACTTION)-American Pain Society (APS) Pain Taxonomy (AAPT) provides an evidence-based, multidimensional, chronic pain classification system. Psychosocial factors play a crucial role within several dimensions of the taxonomy. In this article, we discuss the evaluation of psychosocial factors that influence the diagnosis and trajectory of chronic pain disorders. We review studies in individuals with a variety of persistent pain conditions, and describe evidence that psychosocial variables play key roles in conferring risk for the development of pain, in shaping long-term pain-related adjustment, and in modulating pain treatment outcomes. We consider "general" psychosocial variables such as negative affect, childhood trauma, and social support, as well as "pain-specific" psychosocial variables that include pain-related catastrophizing, self-efficacy for managing pain, and pain-related coping. Collectively, the complexity and profound variability in chronic pain highlights the need to better understand the multidimensional array of interacting forces that determine the trajectory of chronic pain conditions.

PERSPECTIVE

The AAPT is an evidence-based chronic pain classification system in which psychosocial concepts and processes are essential in understanding the development of chronic pain and its effects. In this article we review psychosocial processes that influence the onset, exacerbation, and maintenance of chronic pain disorders.

Combined cognitive biases for pain and disability information in individuals with chronic headache: A preliminary investigation

Pain-related cognitive biases have been demonstrated in chronic pain patients, yet despite theoretical predictions are rarely investigated in combination. Combined cognitive biases were explored in individuals with chronic headache ( n = 17) and pain-free controls ( n = 20). Participants completed spatial cueing (attentional bias), sentence generation (interpretation bias) and free recall tasks (memory bias), with ambiguous sensory-pain, disability and neutral words. Individuals with chronic headache, relative to controls, showed significantly greater interpretation and memory biases favouring ambiguous sensory-pain words and interpretation bias favouring ambiguous disability words. No attentional bias was found. Further research is needed exploring the temporal pattern of cognitive biases.

Suicidal ideation is associated with individual differences in prescription opioid craving and cue-reactivity among chronic pain patients

Given that chronic pain patients experience significant rates of suicidal ideation and suicide attempts, access to prescription opioids compounds the risk of death by suicide. These patients may experience heightened opioid craving and exhibit increased cue-reactivity to stimuli associated with past opioid use when suicidal ideation produces negative affective states. Because both opioids and suicidal behavior are used to alleviate emotional and physical pain through a process of negative reinforcement, elucidating factors that mediate this association may yield insight into suicide risk among chronic pain patients. This study examined the relationship between suicidal ideation and opioid craving and cue-reactivity, and tested opioid self-medication as a mediator of associations between those factors after controlling for the impact of pain severity. A sample of 115 chronic pain patients provided demographic and clinical information on the Obsessive Compulsive Drug Use Scale, the Current Opioid Misuse Measure, and the Brief Pain Inventory before completing an opioid dot probe task in which heart rate variability was recorded. As hypothesized, suicidal ideation was positively correlated with subjective opioid craving and physiological cue-reactivity. Self-medication significantly mediated the association between suicidal ideation, craving, and cue-reactivity. As opioids relieve the emotional pain linked with suicidal thoughts, chronic pain patients with higher levels of suicidal ideation may experience more intense opioid craving and exhibit heightened physiological cue-reactivity when compared to patients with low levels of suicidal ideation.

Keeping an eye on pain: investigating visual attention biases in individuals with chronic pain using eye-tracking methodology

Attentional biases to painful stimuli are evident in individuals with chronic pain, although the directional tendency of these biases (ie, toward or away from threat-related stimuli) remains unclear. This study used eye-tracking technology, a measure of visual attention, to evaluate the attentional patterns of individuals with and without chronic pain during exposure to injury-related and neutral pictures. Individuals with (N=51) and without chronic pain (N=62) completed a dot-probe task using injury-related and neutral pictures while their eye movements were recorded. Mixed-design analysis of variance evaluated the interaction between group (chronic pain, pain-free) and picture type (injury-related, neutral). Reaction time results showed that regardless of chronic pain status, participants responded faster to trials with neutral stimuli in comparison to trials that included injury-related pictures. Eye-tracking measures showed within-group differences whereby injury-related pictures received more frequent fixations and visits, as well as longer average visit durations. Between-group differences showed that individuals with chronic pain had fewer fixations and shorter average visit durations for all stimuli. An examination of how biases change over the time-course of stimulus presentation showed that during the late phase of attention, individuals with chronic pain had longer average gaze durations on injury pictures relative to pain-free individuals. The results show the advantage of incorporating eye-tracking methodology when examining attentional biases, and suggest future avenues of research.

Anxiety sensitivity is associated with attentional bias for pain-related information in healthy children and adolescents

This investigation explored the association between anxiety sensitivity and attentional bias for threatening information in children and adolescents ( N = 40). Participants completed a pictorial version of the visual-probe task, featuring pain-related, health-threat and general-threat images presented for 500 and 1250 ms. Regression analyses revealed significant associations between anxiety sensitivity and attentional bias towards pain-related images presented for 500 ms and between state anxiety and attentional bias towards general-threat images presented for 1250 ms. These results suggest that in children and adolescents, anxiety sensitivity is associated with attentional bias for negative information of personal relevance.

Attentional bias to pain-relevant body locations: New methods, new challenges

In a recent issue of Consciousness and Cognition, Filbrich, Torta, Vanderclausen, Azanon, and Legrain (2016) commented on a paper in which we used a tactile Temporal Order Judgment (TOJ) task to show that expecting pain on a specific body location biased attention to that location (Vanden Bulcke, Crombez, Durnez, & Van Damme, 2015). Their main criticism is that the effects are likely to reflect response bias rather than genuine attentional bias. We agree that the TOJ task used may be susceptible to response bias, and welcome the authors' methodological suggestions to control for such bias. However, we feel that certain aspects of our work are misrepresented in their paper. Most importantly, we contest their argument that our instructions made the threat location task-relevant, thereby increasing risk of response bias. Further, we reply to other methodological and theoretical issues raised by these authors.

Personality Type Influences Attentional Bias in Individuals with Chronic Back Pain

Attentional biases reflect an individual's selective attention to salient stimuli within their environment, for example an experience of back pain. Eysenck suggests that different personality types show different attentional biases to threatening information. This study is the first to test Eysenck's theory within a chronic back pain population by investigating the attentional biases of four different personality types using a back pain specific dot-probe paradigm. Participants were 70 volunteers (45 female) recruited from a back rehabilitation program at an NHS Trust. The four groups were selected on their trait anxiety and defensiveness scores: defensive high-anxious; high-anxious; repressor and non-extreme. Participants completed a dot probe task comprising 20 practice trials and 250 experimental trials. The experimental trials contained 100 threat-neutral pairs, 100 positive-neutral pairs and 50 neutral-neutral image pairings. The threat images were taken from the Photograph Series of Daily Activities (PHODA) and the neutral and positive images from the International Affective Picture System (IAPS) image bank. The results provided partial support for Eysenck's theory; defensive high-anxious individuals showed an attentional bias for threatening information compared to high-anxious individuals who demonstrated no bias. Repressors showed an avoidant bias to threatening images and an attentional bias to positive stimuli relative to neutral images. The clear difference in responses demonstrated by high-anxious individuals who vary in defensiveness highlight the need for separate investigation of these heterogeneous groups and help to explain the cognitive processes of defensive high-anxious individuals within a pain population. The demonstration of an attentional bias in this group to threatening information could explain why defensive high-anxious individuals are more likely to re-present for treatment.

Experimental pain impairs recognition memory irrespective of pain predictability

BACKGROUND

Pain is hardwired to signal threat and tissue damage and therefore automatically attracts attention to initiate withdrawal or defensive behaviour. This well-known interruptive function of pain interferes with cognitive functioning and is modulated by bottom-up and top-down variables. Here, we applied predictable or unpredictable painful heat stimuli simultaneously to the presentation of neutral images to investigate (I) whether the predictability of pain modulated its effect on the encoding of images (episodic memory) and (II) whether subjects remember that certain images have been previously presented with pain (source memory).

METHODS

Twenty-four healthy subjects performed a categorization task in which 80 images had to be categorized into living or non-living objects. We compared the processing and encoding of these images during cued and non-cued pain trials as well as cued and non-cued pain-free trials. Effects on recognition performance and source memory for pain were immediately tested using a surprise recognition task.

RESULTS

Painful thermal stimulation impaired recognition accuracy (d', recollection, familiarity). This negative effect of pain was positively correlated with the individual expectation of pain interference and the attentional avoidance of pain-related words. However, the interruptive effect of pain was not modulated by the predictability of pain. Source memory for painful stimulation was at chance level, indicating that subjects did not explicitly remember that images had been paired with pain.

CONCLUSIONS

Targeting negative expectations and a maladaptive attentional bias for pain-related material might help reducing frequently reported pain-induced cognitive impairments.

Attentional bias in adults with cannabis use disorders

There has been modest examination of attentional bias in individuals with cannabis use disorders. Clinical implications of this work are directly relevant to better informing extant evidence-based treatment for substance use disorders (e.g., relapse prevention) and/or developing novel interventions. The overarching aim of this investigation was to examine a novel attentional bias task in adults with cannabis use disorders. Participants were comprised of 25 adults (8 women: M age = 31, SD = 6.8; range = 22-45) with cannabis use disorders (n = 12) and controls (n = 13) without any current (past month) psychopathology. Relative to controls, adults with cannabis use disorders had greater attentional bias scores. These differences were present only at the 125-ms probe time, where the cannabis use disorders group showed greater attentional bias to cannabis cues than the control group (adjusted p = .001, cannabis use disorders mean = 59.9, control mean = -24.8, Cohen's d-effect size for 125 ms = 1.03). The cannabis use disorders group also reported significantly greater perceived stress and post-task stress scores than the control group, but stress was not related to attentional bias. This study informs understanding of the influence of cannabis cues on visual detection and reaction time under different cue-target onset times, as attentional bias was most prevalent under time pressure to detect the probe.

Painful faces-induced attentional blink modulated by top-down and bottom-up mechanisms

Pain-related stimuli can capture attention in an automatic (bottom–up) or intentional (top–down) fashion. Previous studies have examined attentional capture by pain-related information using spatial attention paradigms that involve mainly a bottom–up mechanism. In the current study, we investigated the pain information-induced attentional blink (AB) using a rapid serial visual presentation (RSVP) task, and compared the effects of task-irrelevant and task-relevant pain distractors. Relationships between accuracy of target identification and individual traits (i.e., empathy and catastrophizing thinking about pain) were also examined. The results demonstrated that task-relevant painful faces had a significant pain information-induced AB effect, whereas task-irrelevant faces showed a near-significant trend of this effect, supporting the notion that pain-related stimuli can influence the temporal dynamics of attention. Furthermore, we found a significant negative correlation between response accuracy and pain catastrophizing score in task-relevant trials. These findings suggest that active scanning of environmental information related to pain produces greater deficits in cognition than does unintentional attention toward pain, which may represent the different ways in which healthy individuals and patients with chronic pain process pain-relevant information. These results may provide insight into the understanding of maladaptive attentional processing in patients with chronic pain.

Attentional bias to respiratory- and anxiety-related threat in children with asthma

This study investigated attentional biases in children with asthma. The study aimed at testing whether children with asthma are vigilant to asthma and/or anxiety cues. Thirty-six children (18 with asthma and 18 healthy controls) aged 9-12 completed a computerised dot probe task designed to measure attentional bias to three different categories of words: asthma, anxiety symptom and general negative emotion. Main caregiver anxiety was also assessed, as was frequency of inhaler use for those with asthma. Children with asthma showed an attentional bias towards asthma words but not anxiety or general negative emotion words. Children without asthma showed no significant attentional biases to any word categories. Caregiver anxiety was correlated with asthma word attentional bias in the asthma group. The findings indicate that attentional bias is present in children with asthma. Further research is required to ascertain if this exacerbates or maintains health-related problems.

Altering attentional control settings causes persistent biases of visual attention

Attentional control settings have an important role in guiding visual behaviour. Previous work within cognitive psychology has found that the deployment of general attentional control settings can be modulated by training. However, research has not yet established whether long-term modifications of one particular type of attentional control setting can be induced. To address this, we investigated persistent alterations to feature search mode, also known as an attentional bias, towards an arbitrary stimulus in healthy participants. Subjects were biased towards the colour green by an information sheet. Attentional bias was assessed using a change detection task. After an interval of either 1 or 2 weeks, participants were then retested on the same change detection task, tested on a different change detection task where colour was irrelevant, or were biased towards an alternative colour. One experiment included trials in which the distractor stimuli (but never the target stimuli) were green. The key finding was that green stimuli in the second task attracted attention, despite this impairing task performance. Furthermore, inducing a second attentional bias did not override the initial bias toward green objects. The attentional bias also persisted for at least two weeks. It is argued that this persistent attentional bias is mediated by a chronic change to participants' attentional control settings, which is aided by long-term representations involving contextual cueing. We speculate that similar changes to attentional control settings and continuous cueing may relate to attentional biases observed in psychopathologies. Targeting these biases may be a productive approach to treatment.

Comparison of acceptance and distraction strategies in coping with experimentally induced pain

BACKGROUND

This study compared an acceptance-based strategy with a control-based strategy (distraction) in terms of the ability of participants to tolerate a painful stimulus, across two experiments. In addition, participants were either actively encouraged, or not, to link pain tolerance with pursuit of valued goals to examine the impact of pursuing a personally meaningful goal or value on the extent to which pain will be tolerated.

METHODS

Participants in experiment 1 (n=41) and experiment 2 (n=52) were equally assigned to acceptance or distraction protocols. Further, half the participants in each group generated examples from their own lives in which they had pursued a valued objective, while the other half did not. In experiment 2, the values focus was enhanced to examine the impact on pain tolerance.

RESULTS

There were no significant differences overall between the acceptance and distraction groups on pain tolerance in either experiment. However, in experiment 2, individuals classified as accepting in terms of general coping style and who were assigned to the acceptance strategy showed significantly better pain tolerance than accepting individuals who were in the distraction condition. Across both experiments, those with strong goal-driven values in both protocols were more tolerant of pain. Participants appeared to have more difficulty adhering to acceptance than to distraction as a strategy.

CONCLUSION

Acceptance may be associated with better tolerance of pain, but may also be more difficult to operationalize than distraction in experimental studies. Matching coping style and coping strategy may be most effective, and enhancement of goal-driven values may assist in pain coping.

Allostatic dysregulation of natural reward processing in prescription opioid misuse: autonomic and attentional evidence

Chronic pain patients who misuse prescription opioids may suffer from allostatic dysregulation of natural reward processing. Hence, this study examined whether prescription opioid misusers with chronic pain (n=72) evidenced decreased natural reward responsiveness relative to non-misusers with chronic pain (n=26). Subjects completed a dot probe task containing pain-related, opioid-related, and natural reward stimuli while attentional bias (AB) scores and heart rate variability (HRV) responses were assessed. Compared to non-misusers, misusers evidenced significantly more attenuated HRV responses to opioid, pain, and natural reward cues presented during the dot probe task. These significant between-groups differences in HRV were largest during attention to natural reward cues, but became non-significant in a sensitivity analysis controlling for opioid dosing. In addition, non-misusers evidenced an AB toward natural reward cues, whereas misusers did not. Findings suggest that opioid misusers exhibit attentional and autonomic deficits during reward processing.

Prevalence and correlates of chronic pain in a random population study of adults in Chongqing, China

OBJECTIVE

Numerous studies have documented rates of chronic pain in developed western nations; however, little is known about its prevalence or correlates in rapidly developing countries, where much of the world's population lives. This study was designed to assess the prevalence of chronic pain among adults in Chongqing, China and the correlates of chronicity among respondents with pain and degree of impairment within the subgroup reporting chronic pain.

DESIGN

A structured telephone interview was used within a cross-sectional design. Chronic pain was defined as the pain that had persisted for ≥3 months.

PARTICIPANTS

Adults from a random sample of 1003 Chongqing households completed a structured telephone interview on pain experiences of themselves and other family members over the past 6 months.

RESULTS

Overall, 42.2% of interviewees reported pain for at least 1 day during the past 6 months and 25.8% experienced pain lasting for at least 3 months. The most common complaints were back pain (17.6%), headache (14.2%), joint pain, (10.5%), and abdominal pain (10.4%). Among those who reported pain, correlates of a chronic duration included older age, presence of back pain, heightened impairment, use of Chinese medicine, and greater numer of interventions used for pain management. For interviewees whose pain was chronic, increased functional impairment was related to older age, presence of pain every day, and increased likelihood of consulting physicians and using Chinese medicine to manage pain.

CONCLUSIONS

Rates of chronic pain in Chongqing appear to approximate to those reported in western countries. A significant minority of those affected report substantial or severe impairment and are more likely than less impaired cohorts to have sought medical interventions to manage pain.

More than meets the eye: visual attention biases in individuals reporting chronic pain

The present study used eye-tracking technology to assess whether individuals who report chronic pain direct more attention to sensory pain-related words than do pain-free individuals. A total of 113 participants (51 with chronic pain, 62 pain-free) were recruited. Participants completed a dot-probe task, viewing neutral and sensory pain-related words while their reaction time and eye movements were recorded. Eye-tracking data were analyzed by mixed-design analysis of variance with group (chronic pain versus pain-free) as the between-subjects factor, and word type (sensory pain versus neutral) as the within-subjects factor. Results showed a significant main effect for word type: all participants attended to pain-related words more than neutral words on several eye-tracking parameters. The group main effect was significant for number of fixations, which was greater in the chronic pain group. Finally, the group by word type interaction effect was significant for average visit duration, number of fixations, and total late-phase duration, all greater for sensory pain versus neutral words in the chronic pain group. As well, participants with chronic pain fixated significantly more frequently on pain words than did pain-free participants. In contrast, none of the effects for reaction time were significant. The results support the hypothesis that individuals with chronic pain display specific attentional biases toward pain-related stimuli and demonstrate the value of eye-tracking technology in measuring differences in visual attention variables.

Decreased activation of cingulo-frontal-parietal cognitive/attention network during an attention-demanding task in patients with chronic low back pain

INTRODUCTION

Attention deficits have been repeatedly reported via neuropsychological assessment in previous literature in patients with chronic low back pain (CLBP). However, there are few functional neuroimaging studies of patients with CLBP during attention processing, and the exact underlying neural mechanisms are yet to be elucidated.

METHODS

We used functional magnetic resonance imaging (fMRI) to measure the function of the cingulo-frontal-parietal (CFP) cognitive/attention network while performing a multi-source interference task (MSIT) in patients with CLBP. Thirty-six patients with CLBP and 36 healthy controls were included in this study. The fMRI data were analyzed with the FSL-FEAT software.

RESULTS

Our results indicated that patients with CLBP showed significantly less activation in the CFP network including the right dorsolateral prefrontal cortex, the dorsal anterior cingulate cortex, and bilateral superior parietal cortex during attention-demanding (MSITinterference > MSITcontrol) trials compared to the healthy controls. A significant negative correlation was found between the scores of the visual analog scale for pain and activation of the right prefrontal cortex during performing the MSIT in patients with CLBP.

CONCLUSION

Our study provides in vivo imaging evidence of abnormal CFP network function during attention-demanding condition in patients with CLBP, which might reflect partly an adaptation/maladaptation of the brain to the chronic pain states.

Fearful thinking predicts hypervigilance towards pain-related stimuli in patients with chronic pain

Cognitive impairment plays a role in the development and maintenance of chronic pain. Patients with painful disorders are reported to show attentional biases toward pain-related information. However, these findings are controversial, and rarely has any study examined whether chronic pain patients have attentional biases to pain-related conditioned stimuli (CS). In this study, twenty-one patients diagnosed with trigeminal neuralgia (TN) were recruited from the neurosurgical department of a large urban general hospital. Sixteen family members and twenty-one pain-free volunteers were included as two separate control groups. Pain ratings, pain-related anxiety, general anxiety, and depression were measured in all subjects using questionnaires. Two dot probe tests were performed, one that used pictures of painful versus neutral faces as cues, and another that presented three types of CS as cues that predicted certain, uncertain, or no pain. Our results demonstrate that the TN patients showed attentional biases towards painful faces and the CSs that signaled uncertain pain. Moreover, the ratings of negative emotion about their pain conditions correlated significantly with the presence of attentional biases. The patients' close family members, however, displayed biases towards uncertain-pain CS. This study demonstrates that patients with chronic pain have increased attention towards pain-related information, and the fearful thinking about pain was positively correlated with this phenomenon.

Mindfulness-oriented recovery enhancement reduces pain attentional bias in chronic pain patients

BACKGROUND

Chronic pain involves hypervigilance for pain-related stimuli. Selective attention to pain-related stimuli, known as pain attentional bias (AB), can exacerbate chronic pain, prolong suffering, and undermine quality of life. The aim of this study was to determine if a multimodal mindfulness-oriented intervention could significantly reduce pain AB among chronic pain patients receiving opioid analgesics.

METHODS

A total of 67 chronic pain patients were randomized to an 8-week Mindfulness-Oriented Recovery Enhancement (MORE) intervention or a social support group intervention and began treatment. A dot probe task was used to measure pain AB. Primary outcomes were pain AB scores for cues presented for 2,000 and 200 ms.

RESULTS

Prior to intervention, participants exhibited a significant bias towards pain-related cues presented for 2,000 ms, but no bias for cues presented for 200 ms. A statistically significant time × intervention condition interaction was observed for 2,000 ms pain AB, such that participants in MORE evidenced significantly reduced posttreatment pain AB relative to pretreatment levels, whereas no significant pre-post treatment changes in pain AB were observed for support group participants. Decreases in pain AB were associated with increased perceived control over pain and attenuated reactivity to distressing thoughts and emotions.

CONCLUSION

Study findings provide the first indication that a mindfulness-oriented intervention may reduce pain AB among adults suffering from chronic pain. Given the magnitude of chronic pain in postindustrial societies, coupled with the dramatic escalation in prescription opioid misuse, future studies should evaluate MORE as a nonpharmacological means of addressing factors linked with chronic pain.

Pain and suicidality: insights from reward and addiction neuroscience

Suicidality is exceedingly prevalent in pain patients. Although the pathophysiology of this link remains unclear, it may be potentially related to the partial congruence of physical and emotional pain systems. The latter system's role in suicide is also conspicuous during setbacks and losses sustained in the context of social attachments. Here we propose a model based on the neural pathways mediating reward and anti-reward (i.e., allostatic adjustment to recurrent activation of the reward circuitry); both are relevant etiologic factors in pain, suicide and social attachments. A comprehensive literature search on neurobiology of pain and suicidality was performed. The collected articles were critically reviewed and relevant data were extracted and summarized within four key areas: (1) physical and emotional pain, (2) emotional pain and social attachments, (3) pain- and suicide-related alterations of the reward and anti-reward circuits as compared to addiction, which is the premier probe for dysfunction of these circuits and (4) mechanistically informed treatments of co-occurring pain and suicidality. Pain-, stress- and analgesic drugs-induced opponent and proponent states of the mesolimbic dopaminergic pathways may render reward and anti-reward systems vulnerable to sensitization, cross-sensitization and aberrant learning of contents and contexts associated with suicidal acts and behaviors. These findings suggest that pain patients exhibit alterations in the brain circuits mediating reward (depressed function) and anti-reward (sensitized function) that may affect their proclivity for suicide and support pain and suicidality classification among other "reward deficiency syndromes" and a new proposal for "enhanced anti-reward syndromes". We suggest that interventions aimed at restoring the balance between the reward and anti-reward networks in patients with chronic pain may help decreasing their suicide risk.