Bruce D. Dick

Disruption of attention and working memory traces in individuals with chronic pain

BACKGROUND: Research has found that chronic pain disrupts attention and that this disruption can lead to significant functional impairment and decreased quality of life. We conducted the present study to examine how attention and memory are disrupted by chronic pain. METHODS: Computerized tests of working memory were given to participants with chronic pain along with a neuropsychological test of attention before and after procedures resulting in analgesia. RESULTS: Two-thirds of participants with chronic pain had scores in the clinically impaired range on attentional tasks. These results were independent of age, education level, sleep disruption, and pain relief. Medication use was also recorded and is reported to account for potential effects of medication on task performance. Those participants with the highest level of impairment had significantly greater difficulties in maintaining a memory trace during a challenging test of working memory. CONCLUSIONS: These findings point to a specific cognitive mechanism, the maintenance of the memory trace, that is affected by chronic pain during task performance. Cognitive function was not improved by short-term local analgesia.

Disruption of cognitive function in Fibromyalgia Syndrome

Abstract Accumulating evidence points to significant cognitive disruption in individuals with Fibromyalgia Syndrome (FMS). This study was carried out in order to examine specific cognitive mechanisms involved in this disruption. Standardized experimental paradigms were used to examine attentional function and working memory capacity in 30 women with FMS and 30 matched controls. Cognitive function was examined using performance on these tests and between group results were analysed in the context of important psychological and behavioural measures. Performance of standardized everyday attentional tasks was impaired in the FMS group compared to controls. Working memory was also found to be impaired in this group. Stimulus interference was found to be significantly worse in the FMS group as the demands of the tasks increased. These effects were found to exist independent of the measures of mood and sleep disruption. However, when pain levels were accounted for statistically, no differences existed between groups on cognitive measures. These findings point to disrupted working memory as a specific mechanism that is disrupted in this population. The results of this study suggest that pain in FMS may play an important role in cognitive disruption. It is likely that many factors, including disrupted cognition, play a role in the reduced quality of life reported by individuals with FMS.

Enhanced Therapeutic Alliance Modulates Pain Intensity and Muscle Pain Sensitivity in Patients With Chronic Low Back Pain: An Experimental Controlled Study

Background Physical therapy influences chronic pain by means of the specific ingredient of an intervention as well as contextual factors including the setting and therapeutic alliance (TA) between provider and patient. Objective The purpose of this study was to compare the effect of enhanced versus limited TA on pain intensity and muscle pain sensitivity in patients with chronic low back pain (CLBP) receiving either active or sham interferential current therapy (IFC). Design An experimental controlled study with repeated measures was conducted. Participants were randomly divided into 4 groups: (1) AL (n=30), which included the application of active IFC combined with a limited TA; (2) SL (n=29), which received sham IFC combined with a limited TA; (3) AE (n=29), which received active IFC combined with an enhanced TA; and (4) SE (n=29), which received sham IFC combined with an enhanced TA. Methods One hundred seventeen individuals with CLBP received a single session of active or sham IFC. Measurements included pain intensity as assessed with a numerical rating scale (PI-NRS) and muscle pain sensitivity as assessed via pressure pain threshold (PPT). Results Mean differences on the PI-NRS were 1.83 cm (95% CI=14.3–20.3), 1.03 cm (95% CI=6.6–12.7), 3.13 cm (95% CI=27.2–33.3), and 2.22 cm (95% CI=18.9–25.0) for the AL, SL, AE, and SE groups, respectively. Mean differences on PPTs were 1.2 kg (95% CI=0.7–1.6), 0.3 kg (95% CI=0.2–0.8), 2.0 kg (95% CI=1.6–2.5), and 1.7 kg (95% CI=1.3–2.1), for the AL, SL, AE, and SE groups, respectively. Limitations The study protocol aimed to test the immediate effect of the TA within a clinical laboratory setting. Conclusions The context in which physical therapy interventions are offered has the potential to dramatically improve therapeutic effects. Enhanced TA combined with active IFC appears to lead to clinically meaningful improvements in outcomes when treating patients with CLBP.

Factors associated with chronic noncancer pain in the Canadian population

Chronic noncancer pain (CNCP) is a prevalent health problem with pervasive negative effects on the individuals quality of life. Previous epidemiological studies of CNCP have suggested a number of individual biological, psychological and societal correlates of CNCP, but it has rarely been possible to simultaneously compare the relative strengths of many such correlates in a Canadian population sample. With data provided by the 1996/1997 Canadian National Population Health Survey, ordinal logistic regression was used to examine the extent to which a number of population variables are associated with CNCP in a large (n=69,365) dataset. The analysis revealed cross-sectional correlations of varying strengths between CNCP and 27 factors. Increasing age, low income, low educational achievement, daily cigarette smoking, physical inactivity and abstention from alcohol were among the factors found to increase CNCP risk. The considerable impact of distress and depression on CNCP are also highlighted. A number of comorbid medical illnesses increased CNCP risk, including some (such as chronic obstructive pulmonary disease, epilepsy and thyroid disease) that have not hitherto been associated with pain. White race and the affirmation of an important role for spirituality or faith reduced CNCP risk. In contrast to some previous studies, female sex did not emerge as an independent CNCP risk. The present exploratory analysis describes associations between CNCP and a number of characteristics from several domains, thus suggesting many areas for further research.

Social information processing in adolescents with chronic pain: My friends don’t really understand me

Summary Friendships of adolescents with chronic pain may be different than those of healthy peers. Differences in cognitive processes during social interactions reveal potential strategies to ameliorate differences. ABSTRACT Adolescents with chronic pain are at risk for impairment in their friendships. They miss out on leisure activities, have increased school absence, may have fewer friends, are at an increased risk for victimization, and may be perceived by peers as less likeable. To help determine the source of these problems, the Social Information Processing Model (SIP) was adapted using narrative vignettes to determine if adolescents with chronic pain interpret friendship interactions differently in terms of supportive and nonsupportive behaviors compared to healthy peers. One hundred seven adolescents, 45 with chronic pain, completed the vignette questionnaire and a battery of measures. The vignette questionnaire included 12 vignettes to capture 3 steps in SIP processing: interpretation of cues, response construction, and response decision. Participants with chronic pain rated nonsupportive vignettes more negatively than healthy controls and indicated they would enact supportive behaviors towards the chronic pain character more often if they had been the healthy character. Age, sex, and internalizing measures did not significantly contribute to the findings. Chronic pain explained 6.5% of variance in the ratings of nonsupportive vignettes and 10.1% of the variance in supportive behavior selection. Adolescents with chronic pain may interpret nonsupportive social situations with close friends as more distressing. The endorsement of more supportive behaviors may indicate a need for, and expectation of, supportive behaviors from friends. When adolescents with chronic pain do not perceive friends as providing support, they may avoid these social situations.

Temporal Dynamics of Reflexive Attention Shifts: A Dual-Stream Rapid Serial Visual Presentation Exploration

We combined a prototypical exogenous cuing procedure with rapid serial visual presentation (RSVP) to provide a precise characterization of the temporal dynamics of reflexive attention shifts. The novel paradigm thus created has several useful properties, most notably that the physical presentation of the target is neither an onset nor a unique event and that temporal precision is provided without the requirement for a speeded response. A biphasic pattern was observed, with early benefits followed by later costs (inhibition of return) at the cued location relative to the uncued location. The finding of inhibition of return in this paradigm disproves the assertion that inhibition of return is merely a reluctance to respond in the targets direction. It may be partly that, but encoding mechanisms linked to attention must also be involved.

The disruptive effect of chronic pain on mismatch negativity

OBJECTIVE To investigate the effect of chronic pain on processes that generate the mismatch negativity (MMN). METHODS Twelve participants with a diagnosis of chronic intractable pain were tested before and after pain treatment. During testing, event-related potentials were recorded while participants performed tasks of varying difficulty. RESULTS The amplitude of the MMN was found to be greater following a nerve block procedure compared to MMN amplitude when participants were experiencing chronic pain. This effect was found to occur in the MMN for difficult-to-detect tones elicited while participants were performing a simultaneous cognitively demanding visual task. MMN amplitude was found to be greater with attention to difficult-to-detect deviants during pain but not in no pain conditions. CONCLUSIONS These results provide an electrophysiological correlate of previous findings that high levels of pain disrupt cognition during the performance of demanding tasks.

A Critical Review of Neurobiological Factors Involved in the Interactions Between Chronic Pain, Depression, and Sleep Disruption.

Aims/Objectives/Background:A significant number of people who experience chronic pain also complain of depression and sleep problems. The comorbidities and bidirectional relationships that exist between these ailments are well recognized clinically. Further, all 3 disorders involve similar alterations in structural and functional neurobiology and share common pathophysiological mechanisms. We sought to comprehensively review the research literature regarding common neurobiological factors associated with these complex clinical disorders in order to better understand how they are related and provide further rationale for future clinical and research efforts to appropriately understand and manage them. Methods:A comprehensive review of the existing research literature was conducted in the domains of chronic pain, depression, and sleep. Results:Although the neurobiological underpinnings of these factors are complex and require further investigation, comparable changes are seen in levels of serotonin (5-hydroxytryptamine), proinflammatory cytokines, brain-derived neurotrophic factor, and other transmitters in these disorders. Conclusions:This review is unique as it attempts to cast a broader net over the common neurobiological correlates that exist across these 3 conditions. It highlights the complexity of the interrelationships between these disorders and the importance of increasing our understanding of neurobiological factors associated with them.

Post-surgical pain syndromes: a review for the non-pain specialist

PurposeThis is a selective narrative review of the latest information about the epidemiology, impact, and prevention of chronic post-surgical pain (CPSP), intended primarily for those without a special interest in pain medicine.Principal findingsChronic post-surgical pain is an important problem in terms of personal impact. It has staggering economic implications, exerts powerful negative effects on the quality of life of many of those it afflicts, and places a significant burden on chronic pain treatment services in general. It is well known that surgery at certain body sites is apt to cause CPSP, but emerging evidence shows a strong correlation between CPSP and demographic (young age, obesity, and female sex) and psychological characteristics (anxiety, depression, stress, and catastrophizing). Severe acute pain is a strong risk factor for CPSP, and this adds yet more weight to the argument that acute pain should be controlled effectively. In specific circumstances, CPSP can be reduced by regional anesthetic techniques, infiltration of local anesthetic, or preoperative use of gabapentin. The ability of other known interrupters of afferent nociceptive transmission—commonly used to reduce CPSP when administered at the time of surgery—is currently unproven, as is the hypothesis that the use of remifentanil during surgery worsens CPSP.ConclusionsReduction of CPSP is a worthy long-term outcome for anesthesia providers to consider as they plan the perioperative care of their patients. More evidence is needed about the effect of currently used analgesics and other perioperative techniques on CPSP.RésuméObjectifVoici un article de synthèse narratif et sélectif des connaissances les plus récentes concernant l’épidémiologie, l’impact et la prévention de la douleur chronique postchirurgicale (DCPC), qui s’adresse principalement aux personnes n’ayant pas d’intérêt particulier pour la médecine de la douleur.Constatations principalesLa douleur chronique postchirurgicale est un problème important en termes d’impact personnel. Elle a des implications économiques dramatiques, exerce des effets négatifs puissants sur la qualité de vie de bon nombre des personnes qu’elle affecte, et constitue un fardeau considérable pour les services de traitement de la douleur chronique en général. Il est bien connu que la chirurgie pratiquée sur certaines parties du corps prédispose à une DCPC, mais de nouvelles données probantes montrent une importante corrélation entre la DCPC et certaines caractéristiques démographiques (jeune âge, obésité et sexe féminin) et psychologiques (anxiété, dépression, stress et catastrophisation). La douleur aiguë grave est un important facteur de risque de DCPC, et cela ajoute encore du poids à l’argument selon lequel la douleur aiguë devrait être contrôlée efficacement. Dans des circonstances spécifiques, la DCPC peut être réduite grâce à des techniques d’anesthésie régionale, à l’infiltration d’anesthésique local ou à l’utilisation préopératoire de gabapentine. La capacité d’autres ‘interrupteurs’ connus de la transmission nociceptive afférente – communément utilisés pour réduire la DCPC lorsqu’ils sont administrés au moment de la chirurgie – est actuellement inconnue, et l’hypothèse selon laquelle l’utilisation de rémifentanil pendant une chirurgie augmenterait la DCPC reste à prouver.ConclusionLa réduction de la DCPC est un pronostic à long terme qu’il vaut la peine de prendre en compte lorsque les professionnels en anesthésie planifient les soins périopératoires de leurs patients. Des données probantes supplémentaires sont nécessaires quant aux effets sur la DCPC des analgésiques et autres techniques périopératoires utilisés actuellement.

The Role of Trait Mindfulness in the Pain Experience of Adolescents

UNLABELLED Trait mindfulness appears to mitigate pain among adult clinical populations and has a unique relationship with pain catastrophizing. However, little is understood about this phenomenon among adolescents. The association between trait mindfulness and pain in both real-world and experimental contexts was examined in a community sample of adolescents. Participants were 198 adolescents who completed measures of trait mindfulness, pain catastrophizing, and pain interference, as well as an interview on day-to-day pain before undergoing an acute experimental pain task. Following the task, they provided ratings of pain intensity and state catastrophizing. Results showed that with regard to day-to-day pains, mindfulness was a significant and unique predictor of pain interference, and this relationship was partially mediated by pain catastrophizing. Mindfulness also had an indirect relationship with experimental pain intensity and tolerance. These associations were mediated by catastrophizing during the pain task. These findings highlight the association between trait mindfulness and both real-world and experimental pain and offer insight into how mindfulness may affect pain among youth. Findings are discussed in the context of current psychological models of pediatric pain and future avenues for research. PERSPECTIVE This article highlights the association between trait mindfulness and pain variables among adolescents in both real-world and experimental pain settings. These findings offer further evidence of the unique relationship between trait mindfulness and pain catastrophizing in affecting pain variables across pain contexts and populations.