Forgetting to remember? Prospective memory within the context of pain.

BACKGROUND: Pain interferes with cognitive functioning in several ways. Among other symptoms, pain patients often report difficulties with remembering future intentions. It remains unclear, however, whether it is the pain per se that impairs prospective remembering or other factors that often characterize people with pain (e.g. poor sleep quality). In this experiment, we investigated whether prospective memory is impaired within the context of pain, and whether this impairment is enhanced when the threat value of pain is increased. METHODS: Healthy participants engaged in an ongoing word categorization task, during which they received either experimental pain stimuli (with or without threatening instructions designed to increase the threat value of pain), or no pain stimuli (no somatic stimuli and no threatening instructions). Crucially, participants were also instructed to perform a prospective memory intention on future moments that would be signalled by specific retrieval cues. RESULTS: Threatening instructions did not differentiate the pain groups in terms of pain threat value; therefore, we only focus on the difference between pain and no pain. Pain and no-pain groups performed the prospective memory intention with similar frequency, indicating that prospective memory is not necessarily impaired when the intended action has to be performed in a painful context. CONCLUSIONS: Findings are discussed in the framework of the multiprocess theory of prospective memory, which differentiates between the spontaneous and the strategic retrieval of intentions. Methodological considerations and suggestions for future research are discussed. SIGNIFICANCE: This laboratory study combines established methods from two research fields to investigate the effects of a painful context on memory for future intentions. Painful context did not impair performance of a prospective memory intention that is assumed to be retrieved by means of spontaneous processing.

Biased pain reports through vicarious information: A computational approach to investigate the role of uncertainty.

Expectations about an impeding pain stimulus strongly shape its perception, yet the degree that uncertainty might affect perception is far less understood. To explore the influence of uncertainty on pain ratings, we performed a close replication of the study of Yoshida, Seymour, Koltzenburg, and Dolan (2013), who manipulated vicarious information about upcoming heat pain and found evidence for uncertainty-induced hyperalgesia. In our study, we presented eight fictitious ratings of previous participants prior the delivery of electrocutaneous pain. The vicarious information was either biased to over- or underreport pain levels based on the participant's psychometric function. We induced uncertainty by manipulating the variation of the vicarious information. As in Yoshida et al. (2013), four computational models were formulated, such that each model represented a different way of how the pain ratings might have been generated by the physical stimulus and the vicarious information. The four competing models were tested against the data of each participant separately. Using a formal model selection criterion, the best model was selected and interpreted. Contrary to the original study, the preferred model for the majority of participants suggested that pain ratings were biased towards the average vicarious information, ignoring the degree of uncertainty. Possible reasons for these diverging results are discussed.

Fear of pain changes movement: Motor behaviour following the acquisition of pain-related fear.

BACKGROUND: According to current fear-avoidance models, changes in motor behaviour (e.g. avoidance) are a key component in the development and maintenance of chronic pain complaints. Yet, experimental research assessing actual behavioural changes following painful events is relatively sparse. This study investigated the effects of pain anticipation on changes in motor behaviour using a fear conditioning paradigm and robot-generated standardized movement trajectories of the upper extremities. METHODS: Pain-free participants (N = 20) performed clockwise and counterclockwise fixed, circular movements with a robotic arm without receiving visual feedback. During fear acquisition, moving in one direction (CS+) was paired with a painful stimulus (pain-US) whereas moving in the other direction (CS-) was not. During the subsequent extinction phase, the pain-US was omitted. We assessed self-reported pain-related fear and urge to avoid the movement, as well as several behavioural measures: Velocity, acceleration, exerted force and force direction. RESULTS: Movements that were paired with pain were associated with increased self-reported pain-related fear and urge to avoid. Moreover, movements that were associated with pain were performed faster, more forcefully and more accurately than movements that were not associated with pain. All these differences diminished during the extinction phase. CONCLUSIONS: The present study demonstrates the utility of robot-generated force feedback in the study of pain-related fear and associated changes in motor behaviour. SIGNIFICANCE: Fear of pain changes movement: Movements associated with pain are performed faster, with more force and higher accuracy than movements that are not associated with pain. These changes can inform us how fear of pain translates into avoidance and escape behaviour, two important constructs in the maintenance of chronic pain.

Attention allocation to ambiguous health/somatic threat cues.

BACKGROUND: An influential idea is that attentional bias to information related to pain or pain-related negative affect underlies persistent pain problems. Such information is however often ambiguous. If ambiguous input is perceived as pain or threat related, attention to this stimulus would be enhanced compared with stimuli with no (dominant) pain-/threat-related meaning. Attentional bias to ambiguous stimuli related to somatic/health threat was expected to be more pronounced with higher levels of pain catastrophizing. METHODS: University students performed a spatial cueing task including four types of word cues that were combinations of word content (somatic/health threat vs. non-threat), and word ambiguity (unambiguous vs. ambiguous), each presented for 500 or 750 ms. Attentional bias to somatic/health threat is reflected in larger cue validity effects for somatic/heath threat words than for non-threat words. RESULTS: In the 500-ms condition, cue validity effects were larger for threat than for non-threat words in participants reporting low catastrophizing, but did not depend on word content in participants reporting higher catastrophizing. In the 750-ms condition, cue validity effects did not depend on pain catastrophizing or word content. Cue validity effects did not significantly differ between unambiguous words and ambiguous homographs. CONCLUSIONS: Low catastrophizers demonstrated attentional bias to threat content. Participants reporting higher catastrophizing showed overall enhanced attentional orienting. There was no evidence for differences in (biased) attention to unambiguous and ambiguous words. Further research is needed to determine attentional bias for ambiguous pain-/threat-related stimuli in the context of consistent attentional bias for unambiguous pain-/threat-related stimuli.

Response inhibition predicts painful task duration and performance in healthy individuals performing a cold pressor task in a motivational context.

BACKGROUND: Long-term avoidance of painful activities has shown to be dysfunctional in chronic pain. Pain may elicit escape or avoidance responses automatically, particularly when pain-related fear is high. A conflict may arise between opposing short-term escape/avoidance goals to reduce pain and long-term approach goals to receive a reward. An inhibitory control system may resolve this conflict. It was hypothesized that reduced response inhibition would be associated with greater escape/avoidance during pain, particularly among subjects with higher pain-related fear. METHODS: Response inhibition was measured with the stop-signal task, and pain-related fear with the Fear of Pain Questionnaire. Participants completed a tone-detection task (TDT) in which they could earn money while being exposed to cold pressor pain. Escape/avoidance was operationalized as the hand immersion time during a cold pressor task (CPT) and the performance on the TDT. RESULTS: Poorer response inhibition was associated with shorter CPT immersion duration and with worse TDT performance. Pain after the CPT was associated with pain-related fear, but not with response inhibition. No supportive evidence was found for the hypothesis that the relation between inhibition and escape/avoidance would be most pronounced for those with higher pain-related fear. In contrast, the relation between response inhibition and number of hits on the TDT was most pronounced for those with lower pain-related fear. CONCLUSIONS: The findings suggest that individuals with a stronger ability to inhibit responses in a stop-signal task are better able to inhibit escape/avoidance responses elicited by pain, in the service of a conflicting approach goal.

Pain catastrophizing moderates the effects of pain-contingent task interruptions.

BACKGROUND: A prominent behavioural consequence of pain is the temporary suspension of current activities with intent to resume them later. Little is known about the effects of such pain-contingent task interruptions. This experiment examines the influence of pain-contingent interruptions on the amount of time spent performing a cognitive achievement task: We expected that people would spend more time on task when task performance was interrupted in response to pain (vs. no interruption), and that negative mood and pain catastrophizing would enhance this negative impact. METHODS: Healthy volunteers read behaviour descriptions until they felt they could form a good impression. Before task performance, participants underwent a negative or positive mood induction. During the task, all participants expected painful stimulation. Half of the participants in each mood induction group received an acute (electrocutaneous) pain stimulus, resulting in a 2-min break from the task. The other participants received no sensory stimulation during task performance and their performance was not interrupted. RESULTS: Results revealed no effect of mood on task performance (i.e., total number of descriptions read). There was, however, a significant interaction between task interruption and pain catastrophizing, indicating that participants with low levels of catastrophizing tended to read more descriptions when performance was interrupted than when not, whereas participants reporting relatively high levels of catastrophizing showed the reverse behavioural pattern. CONCLUSIONS: The impact of pain-contingent task interruptions was reversed in participants reporting relatively high levels of pain catastrophizing. Results are discussed with regard to interruption management in the context of chronic pain.

The fidelity of treatment delivery can be assessed in treatment outcome studies: a successful illustration from behavioral medicine.

OBJECTIVES: Treatment outcome studies ought to assess the fidelity of their treatments, including treatment delivery, but practical guidelines and examples for this are lacking. Based on general recommendations in available literature, this study proposes and illustrates the design and application of a Method of Assessing Treatment Delivery (MATD) in a behavioral medicine trial comparing two treatments for chronic low back pain. STUDY DESIGN AND SETTING: In designing MATD, two experts identified several feasible treatment elements. Agreement between the experts in classifying these elements into five categories (essential and unique, essential but not unique, unique but not essential, compatible, prohibited) was assessed. In applying MATD, treatment recordings were evaluated by two independent raters, who coded the (non)-occurrence of MATD elements and who categorized each session as belonging to one of the two treatments. RESULTS: MATDs content validity was supported by adequate agreement between the experts' classifications of the treatment elements. MATDs interrater reliability was good. CONCLUSION: Comprehensive illustrations of designing and applying MATD may encourage the verification of treatment delivery as a partial reflection of treatment fidelity in forthcoming treatment outcome studies.

Fear of movement/injury in the general population: factor structure and psychometric properties of an adapted version of the Tampa Scale for Kinesiophobia.

In recent years, several studies have pointed out the importance of pain-related fear in the development and maintenance of chronic pain. An important instrument for measuring pain-related fear in the context of low back pain is the Tampa Scale for Kinesiophobia (TSK). Recently, a version of this questionnaire has been developed for administration among the general population (TSK-G). To determine the factor structure of the TSK-G, data from a random sample of the Dutch general population were studied separately for people who had had back complaints in the previous year, and people who had been without back complaints. For both groups the TSK-G appeared to consist of one, internally consistent, factor of 12 items. The one-factor TSK-G also appeared valid after comparison with scores on measures of catastrophizing and general health status.

Do health care providers' attitudes towards back pain predict their treatment recommendations? Differential predictive validity of implicit and explicit attitude measures.

The current study aimed to measure the differential predictive value of implicit and explicit attitude measures on treatment behaviour of health care providers. Thirty-six physiotherapy students completed a measure of explicit treatment attitude (Pain Attitudes And Beliefs Scale For Physiotherapists-PABS-PT) and a measure of implicit treatment attitude (Extrinsic Affective Simon Task-EAST). Furthermore, they gave treatment recommendations for a patient simulating back pain on three video scenes. The implicit and explicit measures of attitudes were only weakly related to each other. However, both were differentially related to treatment recommendations. The implications of the differential predictive value of implicit and explicit attitude measures for treatment behaviour are discussed.

Behavioural treatment for chronic low-back pain.

BACKGROUND: Behavioural treatment, commonly used in the treatment of chronic low-back pain (CLBP), is primarily focused at reducing disability through the modification of environmental contingencies and cognitive processes. In general, three behavioural treatment approaches are distinguished: operant, cognitive and respondent. OBJECTIVES: To determine if behavioural therapy is more effective than reference treatments for CLBP, and which type of behavioural treatment is most effective. SEARCH STRATEGY: We searched the CENTRAL, MEDLINE, EMBASE, and PsycLIT databases up to October 2003. References of identified randomised trials and relevant systematic reviews were screened. SELECTION CRITERIA: Only randomised trials on behavioural treatment for non-specific CLBP were included. DATA COLLECTION AND ANALYSIS: Two reviewers independently assessed the methodological quality and extracted the data. The magnitude of effect was assessed by computing a pooled effect size for post-treatment and long-term results for each comparison, for each domain (i.e., behavioural outcomes, overall improvement, back pain specific and generic functional status, return to work, and pain intensity) using the random effects model. MAIN RESULTS: Seven studies (33%) were considered high quality. Comparing behavioural treatment to waiting list control (WLC) revealed strong evidence (4 trials, 134 people) in favour of a combined respondent-cognitive therapy for a medium positive effect on pain, and moderate evidence (2 trials, 39 people) in favour of progressive relaxation for a large positive effect on pain and behavioural outcomes (short-term only). When comparing operant treatment to WLC no significant differences could be detected on general functional status (strong evidence: 2 trials, 87 people) or on behavioural outcomes (moderate evidence; 3 trials, 153 people) (short-term only). There is limited evidence (1 trial, 98 people) that a graded activity program in an industrial setting is more effective than usual care for early return to work and reduced long-term sick leave. There is limited evidence (1 trail, 39 people) that there are no differences between behavioural treatment and exercises. Finally, there is moderate evidence (6 trials, 210 people) that there are no significant differences in short-term and long-term effectiveness when behavioural components are added to usual treatment programs for CLBP (i.e. physiotherapy, back education) on pain, generic functional status and behavioural outcomes. AUTHORS' CONCLUSIONS: Combined respondent-cognitive therapy and progressive relaxation therapy are more effective than WLC on short-term pain relief. However, it is unknown whether these results sustain in the long term. No significant differences could be detected between behavioural treatment and exercise therapy. Whether clinicians should refer patients with CLBP to behavioural treatment programs or to active conservative treatment cannot be concluded from this review.

Health care provider's attitudes and beliefs towards chronic low back pain: the development of a questionnaire.

Attitudes and beliefs, or the treatment orientation, of health care providers appear to be important in the management of non-specific chronic low back pain (CLBP). The aims of the current study were two-fold: First of all, the physiotherapists' opinion towards various aspects of the management of CLBP was surveyed. Secondly, in a principal factor analysis, it was investigated whether underlying dimensions could be identified in order to develop the Pain Attitudes and Beliefs Scale for Physiotherapists (PABS_PT). In total, 421 physiotherapists (response rate 62.3%) participated in this study. The results suggested that the majority of physiotherapists hold the opinion that CLBP is not a dangerous condition, that sport should not be discouraged and that patients should not refrain from all physical activity. Moreover physiotherapists seem to hold the opinion that the way patients view their pain influences the progress of symptoms. Finally, physiotherapists seem to hold the opinion that therapy can completely alleviate the functional symptoms and that therapy may have been successful even if pain remains. The principal factor analysis (PAF) yielded an interpretable 2-factor model. Based on highest loading items, factor 1 was labelled 'biomedical orientation', whereas factor 2 was labelled 'behavioural orientation'. The internal consistency (Cronbach's Alpha) of factor 1 was 0.84 and for factor 2, 0.54 explaining 25.2% and 8.2%, respectively, of the total variance. Assessment of the effect of the physiotherapists' characteristics on scores on the different scales was encouraging as results pointed in the directions one would expect. Physiotherapists who attended biopsychosocial education courses had statistically significantly higher scores on the 'behavioural orientation' factor and vice versa. Biomedical specialists scored statistically significantly higher on the 'biomedical orientation' factor. Furthermore, the findings suggested that the PABS_PT discriminates between physiotherapists with a 'behavioural orientation' vs those with a 'biomedical orientation'. To examine the influence of these different treatment orientations with regard to CLBP on patient outcome is a challenge for the near future.

Effectiveness of behavioral graded activity after first-time lumbar disc surgery: short term results of a randomized controlled trial.

Behavioral approaches to treating patients following lumbar disc surgery are becoming increasingly popular. The treatment method is based on the assumption that pain and pain disability are not only influenced by somatic pathology, if found, but also by psychological and social factors. A recent study highlighted the effectiveness of cognitive-behavioral interventions, as compared to no treatment, for chronic low back patients. However, to the authors' knowledge, there is no randomized controlled trial that evaluates a behavioral program for patients following lumbar disc surgery. The purpose of this study was to assess the effectiveness of a behavioral graded activity (BGA) program compared to usual care (UC) in physiotherapy following first-time lumbar disc surgery. The BGA program was a patient-tailored intervention based upon operant therapy. The essence of the BGA is to teach patients that it is safe to increase activity levels. The study was designed as a randomized controlled trial. Assessments were carried out before and after treatment by an observer blinded to treatment allocation. Patients suffering residual symptoms restricting their activities of daily living and/or work at the 6 weeks post-surgery consultation by the neurosurgeon were included. The exclusion criteria were: complications during surgery, any relevant underlying pathology, and any contraindication to physiotherapy or the BGA program. Primary outcome measures were the patient's Global Perceived Effect and the functional status. Secondary measures were: fear of movement, viewing pain as extremely threatening, pain, severity of the main complaint, range of motion, and relapses. Physiotherapists in the BGA group received proper training. Between November 1997 and December 1999, 105 patients were randomized; 53 into the UC group and 52 into the BGA group. The unadjusted analysis shows a 19.3% (95% CI: 0.1 to 38.5) statistically significant difference to the advantage of the UC group on Global Perceived Effect. This result, however, is not robust, as the adjusted analyses reveal a difference of 15.7% (95% CI: -3.9 to 35.2), which is not statistically significant. For all other outcome measures there were no statistically significant or clinically relevant differences between the two intervention groups. In general, the physiotherapists' compliance with the BGA program was satisfactory, although not all treatments, either in the BGA or the UC group, were delivered exactly as planned, resulting in less contrast between the two interventions than had been planned for. There was one re-operation in each group. The BGA program was not more effective than UC in patients following first-time lumbar disc surgery. For Global Perceived Effect there was a borderline statistically significant difference to the advantage of the UC group. On functional status and all other outcome measures there were no relevant differences between interventions. The number of re-operations was negligible, indicating that it is safe to exercise after first-time disc surgery.

Psychometric properties of the Tampa Scale for kinesiophobia and the fear-avoidance beliefs questionnaire in acute low back pain.

The transition from acute to chronic low back pain (LBP) is influenced by many interacting factors. Pain-related fear, as measured by the Tampa Scale for Kinesiophobia (TSK) and the Fear-Avoidance Beliefs Questionnaire (FABQ), is one of these factors. The objectives of this study were to investigate, in a population with acute LBP, the reliability of TSK and FABQ through evaluation of the internal consistency, the test-retest reliability, and the concurrent validity between TSK and FABQ. One hundred and Seventy-Six patients suffering LBP for no longer than 4 weeks completed a Visual Analogue Scale for pain (VAS), the TSK, the FABQ, and a socio-demographic questionnaire. Each patient completed the VAS, TSK, and FABQ twice within 24 h. Internal consistency of TSK and FABQ scores range from alpha=0.70 to 0.83. Test-retest reliability ranges from r(s)=0.64 to 0.80 (P<0.01). Concurrent validity is moderate, ranging from r(s) =0.33 to 0.59 (P<0.01). It may be concluded that in a population with acute LBP, both the TSK and the FABQ are reliable measures of pain-related fear. In the clinical setting they may provide the practitioner a means of identifying pain-related fear in a patient with acute LBP.

Dutch version of the Pain Vigilance and Awareness Questionnaire: validity and reliability in a pain-free population.

The current study examined validity and reliability of the Pain Vigilance and Awareness Questionnaire (PVAQ) in two samples of healthy college students. Exploratory and confirmatory factor analysis showed that a two-factor model of the PVAQ was most suitable in the present study. The first factor could be referred to as attention to pain whereas the second factor could be specified as attention to changes in pain. With regard to the convergent and divergent validity, the PVAQ was found to correlate highly with related constructs like catastrophising (PCS) and general body vigilance (BVQ). The correlation between PVAQ and pain-related fear (FPQ) was moderate, whereas correlations with unrelated constructs like trait anxiety (STAI-T) and fear of spiders (FSQ) were low. Furthermore, the PVAQ showed good internal consistency and fair test-retest reliability. Altogether, these findings suggest that the PVAQ is a valid and reliable measure of pain vigilance in healthy individuals. The results of this study can be regarded as a starting point for further validation of the PVAQ in clinical pain populations. Implications for future research and treatment interventions are discussed.