Executive function in chronic pain patients and healthy controls: different cortical activation during response inhibition in fibromyalgia

Vocal response inhibition is enhanced by anodal tDCS over the right prefrontal cortex

Stopping outright (reactive inhibition) and slowing down (proactive inhibition) are types of response inhibition which have mainly been investigated in the manual effector system. This study compared reactive inhibition across manual and vocal effector systems, examined the effects of excitatory anodal transcranial direct current stimulation (anodal tDCS) over the right prefrontal cortex (right-PFC) and looked at the relationship between reactive and proactive inhibition. We hypothesised (1) that vocal reactive inhibition would be less effective than manual reactive inhibition as evidenced by longer stop signal reaction times; (2) that anodal tDCS would enhance both vocal and manual reactive inhibitions and (3) that proactive and reactive inhibitions would be positively related. We tested 14 participants over two sessions (one session with anodal tDCS and one session with sham stimulation) and applied stimulation protocol in the middle of the session, i.e. only during the second of three phases. We used a stop signal task across two stop conditions: relevant and irrelevant stop conditions in which stopping was required or ignored, respectively. We found that reactive inhibition was faster during and immediately after anodal tDCS relative to sham. We also found that greater level of proactive inhibition enhanced reactive inhibition (indexed by shorter stop signal reaction times). These results support the hypothesis that the right-PFC is part of a core network for reactive inhibition and supports previous contention that proactive inhibition is possibly modulated via preactivating the reactive inhibition network.

Persistent neuropathic pain influences persistence behavior in rats

AIMS

To determine whether self-regulation can be studied successfully in a rodent model and whether persistent facial pain influences self-regulatory behavior.

METHODS

Thirty male Sprague-Dawley rats, divided into two groups, (1) chronic constriction injury of the infraorbital nerve (CCI-ION) and (2) naïve, were used in a two-part behavioral paradigm of self-regulation. This paradigm consisted of both a cued go/no-go task (part one) and a persistence trial (part two). All animals were acclimated and trained for a period of 4 weeks prior to the experimental manipulation and then tested for a total of 5 weeks following experimental manipulation. Results were analyzed with t tests, one-way analysis of variance, and two-way, repeated measures analysis of variance.

RESULTS

CCI-ION surgery induced significant mechanical hypersensitivity of the ipsilateral whisker pad that began 3 weeks postsurgery and persisted through the duration of the experiment (P < .001). At weeks 4 and 5 post-experimental manipulation, naïve animals demonstrated a significant decrease in lever presses during the persistence task (P < .05) compared to baseline, whereas CCI-ION animals did not (P = .55).

CONCLUSION

These results suggest that persistent pain influences behavioral regulation and that animals experiencing persistent pain may have difficulty adapting to environmental demands.

Neurobiological Phenotypes of Familial Chronic Pain in Adolescence: A Pilot fMRI Study

Parental history of chronic pain has been associated with self-reported pain in adolescent offspring. This suggests that there may be neurobiological mechanisms associated with pain heritability. Because emotional circuitry is an important component of pain processing and may also influence cognition, we used functional magnetic resonance imaging to examine affective processing and cognitive control using an Emotional Go/NoGo task in youth with (FH + Pain, n = 8) and without (FH - Pain, n = 8) a parental history of chronic pain (mean age = 14.17 ± .34 years). FH + Pain youth had widespread reductions in brain activity within limbic and visual processing regions during processing of positively valenced emotional stimuli, as well as reduced frontoparietal response while processing negatively valenced emotional stimuli compared with their peers. In addition, during inhibition within a positive emotional context, FH + Pain youth had reduced cognitive control and salience-related brain activity. On the other hand, default mode-related brain response was increased during inhibitory control within a negative emotional context in these adolescents compared with their peers (P/α < .05). The current findings indicate differences in both emotional processing and cognitive control brain response in FH + Pain compared with FH - Pain youth, suggesting that both affective and executive functioning pathways may be important markers related to the intergenerational transmission of pain. Perspective: This is the first study to examine neurobiological markers of pain risk in adolescents with a family history of chronic pain. These findings may aid in the identification of neural phenotypes related to vulnerability for the onset of pain in at-risk youth.

Fibromyalgia, Fibro Fog, and Exercise

Fibro fog causes serious problems for those with fibromyalgia syndrome. The mechanisms that cause it have not been well identified. Since prescription medication and other conventional medical interventions have proven less than satisfactory, and while waiting for more investigational information, research suggests that exercise might be helpful.

Self-perspective leads to increased activation of pain processing brain regions in fibromyalgia

BACKGROUND

Dysfunction of central nervous pain processing is assumed to play a key role in primary fibromyalgia (FM) syndrome. This pilot study examined differences of pain processing associated with adopting different interpersonal perspectives.

METHODS

Eleven FM patients and 11 healthy controls (HC) were scanned with functional magnetic resonance imaging. Participants were trained to take either a self-perspective or another person's perspective when viewing the visual stimuli. Stimuli showed body parts in painful situations of varying intensity (low, medium, and high) and visually similar but neutral situations.

RESULTS

Patients with FM showed a higher increase in blood oxygen level dependent (BOLD) response, particularly in the supplementary motor area (SMA). All pain-related regions of interest (anterior insula, somatosensory cortices, anterior cingulate cortex, and SMA) showed stronger modulation of BOLD responses in FM patients in the self-perspective. In contrast to pain processing regions, perspective-related regions (e.g. temporoparietal junction) did not differ between FM and HC.

CONCLUSIONS

The stronger response of all four pain processing cerebral regions during self-perspective is discussed in the light of disturbed bottom-up processing. Furthermore, the results confirm earlier reports of augmented pain processing in FM, and provide evidence for sensitization of central nervous pain processing.

Brain alterations and neurocognitive dysfunction in patients with complex regional pain syndrome

Few studies have examined the involvement of specific subregions of the prefrontal cortex in complex regional pain syndrome (CRPS). We analyzed cortical thickness to identify morphologic differences in local brain structures between patients with CRPS and healthy control subjects (HCs). Furthermore, we evaluated the correlation between cortical thickness and neurocognitive function. Cortical thickness was measured in 25 patients with CRPS and 25 HCs using the FreeSurfer method. Pain severity and psychiatric symptoms were assessed using the Short Form McGill Pain Questionnaire and the Beck Depression and Anxiety Inventories, respectively. Neurocognitive function was assessed via the Wisconsin Card Sorting Test and the stop-signal task. The right dorsolateral prefrontal cortex and left ventromedial prefrontal cortex were significantly thinner in CRPS patients than in HCs. CRPS patients made more perseveration errors on the Wisconsin Card Sorting Test and had longer stop-signal task reaction times than HCs. Although the Beck Depression Inventory and the Beck Anxiety Inventory differ significantly between the groups, they were not correlated with cortical thickness. Our study suggests that the pathophysiology of CRPS may be related to reduced cortical thickness in the dorsolateral prefrontal cortex and the ventromedial prefrontal cortex. The structural alterations in dorsolateral prefrontal cortex may explain executive dysfunction and disinhibited pain perception in CRPS.

PERSPECTIVE

The present study reports decreased cortical thickness in the prefrontal cortex and neurocognitive dysfunctions in patients with CRPS. These findings may contribute to the understanding of pain-related impairments in cognitive function and could help explain the symptoms or progression of CRPS.

Reaction time, cerebral blood flow, and heart rate responses in fibromyalgia: Evidence of alterations in attentional control

The study investigated cerebral blood flow (CBF) and heart rate (HR) responses during a cued reaction time (RT) task in patients with fibromyalgia syndrome (FMS). CBF velocities in the middle (MCA) and anterior (ACA) cerebral arteries of both hemispheres were recorded in 46 patients and 32 healthy control participants using functional transcranial Doppler sonography (fTCD). Patients exhibited markedly longer RT than healthy participants. Group differences in CBF responses were mainly observed for both ACAs, with greater right hemispherical increases but lower left hemispherical increases in FMS patients than in healthy participants. HR deceleration around the imperative stimulus was more pronounced in healthy participants. RT was inversely related to increases in CBF in both right arteries and in the left ACA in the FMS group, but was positively associated with CBF responses in all four arteries in healthy participants. The magnitude of task-induced HR deceleration correlated negatively with RT in both groups. Patients' clinical pain severity was positively associated with RT and CBF responses; trait anxiety and insomnia were secondary negative predictors of CBF responses. The study provided evidence of a deficit in the alertness component of attention in FMS at behavioral, CBF, and autonomic levels. These results may be interpreted in terms of the neural efficiency hypothesis of intelligence (i.e., less efficient brain activation during cognition in FMS) and the interfering effect of clinical factors on cognition. Clinical factors such as pain, anxiety, and sleep disturbances can affect cognition in FMS by interfering with CBF adjustment to cognitive demands.

Partial recovery of abnormal insula and dorsolateral prefrontal connectivity to cognitive networks in chronic low back pain after treatment

We previously reported that effective treatment of chronic low back pain (CLBP) reversed abnormal brain structure and functional MRI (fMRI) activity during cognitive task performance, particularly in the left dorsolateral prefrontal cortex (DLPFC). Here, we used resting-state fMRI to examine how chronic pain affects connectivity of brain networks supporting cognitive functioning and the effect of treatment in 14 CLBP patients and 16 healthy, pain-free controls (scans were acquired at baseline for all subjects and at 6-months post-treatment for patients and a matched time-point for 10 controls). The main networks activated during cognitive task performance, task-positive network (TPN) and task-negative network (TNN) (aka default mode) network, were identified in subjects' task fMRI data and used to define matching networks in resting-state data. The connectivity of these cognitive resting-state networks was compared between groups, and before and after treatment. Our findings converged on the bilateral insula (INS) as the region of aberrant cognitive resting-state connectivity in patients pretreatment versus controls. These findings were complemented by an independent, data-driven approach showing altered global connectivity of the INS. Detailed investigation of the INS confirmed reduced connectivity to widespread TPN and TNN areas, which was partially restored post-treatment. Furthermore, analysis of diffusion-tensor imaging (DTI) data revealed structural changes in white matter supporting these findings. The left DLPFC also showed aberrant connectivity that was restored post-treatment. Altogether, our findings implicate the bilateral INS and left DLPFC as key nodes of disrupted cognition-related intrinsic connectivity in CLBP, and the resulting imbalance between TPN and TNN function is partially restored with treatment.

Unraveling the relationship between trait negative affectivity and habitual symptom reporting

Objective

In two studies, we aimed at further elucidating the relationship between trait negative affectivity (NA) and habitual symptom reporting (HSR) by relating these variables to measures of executive function, trait questionnaires, and effects of emotion induction.

Methods

Healthy female participants (N = 75) were selected on their scores for trait NA and for the Checklist for Symptoms in Daily Life. Three groups were compared: (1) low NA-low HSR; (2) high NA-low HSR; and (3) high NA-high HSR (low NA-high HSR did not occur). In study 1, participants underwent a Parametric Go/No-go Task and a Stroop Color-Word test, and trait questionnaires measured alexithymia and absorption. Forty-five participants (N = 15 in each group) were further engaged in study 2 to induce state NA using an affective picture paradigm.

Results

Impaired inhibition on the Stroop and Go/No go Task characterized high trait NA, but not high HSR, whereas alexithymia and absorption were elevated in HSR, regardless of trait NA. Negative picture viewing induced elevated state NA in all groups, but only high HSR also reported more bodily symptoms. This effect was moderated, but not mediated by state NA.

Conclusion

High trait NA is a vulnerability factor but not a sufficient condition to develop HSR. Deficient inhibition is related to the broad trait of NA, whereas the moderating effect of state NA on symptom reporting is specific for high HSR. Understanding processes related to alexithymia and absorption may specifically help to explain elevated HSR.

Neuropsychological function, anxiety, depression and pain impact in fibromyalgia patients

Cognitive deficits have a significant impact on the daily performance of fibromyalgia patients. This paper analyzes executive functioning and decision-making performance, and the relationships between these functions and pain, anxiety, depression and medication in fibromyalgia patients. A group of fibromyalgia patients (FG) (n = 85) was compared with a healthy control group (CG) (n = 85) in their performance in the Wisconsin Card Sorting Test (WCST) and the Iowa Gambling Task (IGT). In the WCST, results showed a percentage of non-perseverative errors significantly higher in the CG than in the FG (p = .026), the other variables (percentage of perseverative errors, number of categories and failures to maintain set) showed no significant differences. In relation to decision-making (IGT), once the rules had been learnt, the FG made fewer advantageous choices than the CG, but these differences were not statistically significant (p = .325). In the FG, pain severity (p = .010) and impact on daily activities (p = .016) interfered with decision-making, unlike anxiety, depression or medication, which did no relate to it. In executive function, pain and impact on daily activities were associated with the percentage of perseverative errors (p = .051) and the number of categories (p = .031), whereas pain severity was related to failures to maintain set (p = .039), indicative of increased distractibility and poor attentional ability. In conclusion, FG showed normal performance in executive functioning and decision-making. Moreover, pain was associated with neuropsychological functioning whereas anxiety, depression and medication were not.

Neuroimaging chronic pain: what have we learned and where are we going?

Advances in neuroimaging have helped illuminate our understanding of how the brain works in the presence of chronic pain, which often persists with unknown etiology or after the painful stimulus has been removed and any wounds have healed. Neuroimaging has enabled us to make great progress in identifying many of the neural mechanisms that contribute to chronic pain, and to pinpoint the specific regions of the brain that are activated in the presence of chronic pain. It has provided us with a new perception of the nature of chronic pain in general, leading researchers to move toward a whole-brain approach to the study and treatment of chronic pain, and to develop novel technologies and analysis techniques, with real potential for developing new diagnostics and more effective therapies. We review the use of neuroimaging in the study of chronic pain, with particular emphasis on magnetic resonance imaging.

Aquatic exercise training for fibromyalgia

BACKGROUND

Exercise training is commonly recommended for individuals with fibromyalgia. This review examined the effects of supervised group aquatic training programs (led by an instructor). We defined aquatic training as exercising in a pool while standing at waist, chest, or shoulder depth. This review is part of the update of the 'Exercise for treating fibromyalgia syndrome' review first published in 2002, and previously updated in 2007.

OBJECTIVES

The objective of this systematic review was to evaluate the benefits and harms of aquatic exercise training in adults with fibromyalgia.

SEARCH METHODS

We searched The Cochrane Library 2013, Issue 2 (Cochrane Database of Systematic Reviews, Database of Abstracts of Reviews of Effects, Cochrane Central Register of Controlled Trials, Health Technology Assessment Database, NHS Economic Evaluation Database), MEDLINE, EMBASE, CINAHL, PEDro, Dissertation Abstracts, WHO international Clinical Trials Registry Platform, and AMED, as well as other sources (i.e., reference lists from key journals, identified articles, meta-analyses, and reviews of all types of treatment for fibromyalgia) from inception to October 2013. Using Cochrane methods, we screened citations, abstracts, and full-text articles. Subsequently, we identified aquatic exercise training studies.

SELECTION CRITERIA

Selection criteria were: a) full-text publication of a randomized controlled trial (RCT) in adults diagnosed with fibromyalgia based on published criteria, and b) between-group data for an aquatic intervention and a control or other intervention. We excluded studies if exercise in water was less than 50% of the full intervention.

DATA COLLECTION AND ANALYSIS

We independently assessed risk of bias and extracted data (24 outcomes), of which we designated seven as major outcomes: multidimensional function, self reported physical function, pain, stiffness, muscle strength, submaximal cardiorespiratory function, withdrawal rates and adverse effects. We resolved discordance through discussion. We evaluated interventions using mean differences (MD) or standardized mean differences (SMD) and 95% confidence intervals (95% CI). Where two or more studies provided data for an outcome, we carried out meta-analysis. In addition, we set and used a 15% threshold for calculation of clinically relevant differences.

MAIN RESULTS

We included 16 aquatic exercise training studies (N = 881; 866 women and 15 men). Nine studies compared aquatic exercise to control, five studies compared aquatic to land-based exercise, and two compared aquatic exercise to a different aquatic exercise program.We rated the risk of bias related to random sequence generation (selection bias), incomplete outcome data (attrition bias), selective reporting (reporting bias), blinding of outcome assessors (detection bias), and other bias as low. We rated blinding of participants and personnel (selection and performance bias) and allocation concealment (selection bias) as low risk and unclear. The assessment of the evidence showed limitations related to imprecision, high statistical heterogeneity, and wide confidence intervals. Aquatic versus controlWe found statistically significant improvements (P value < 0.05) in all of the major outcomes. Based on a 100-point scale, multidimensional function improved by six units (MD -5.97, 95% CI -9.06 to -2.88; number needed to treat (NNT) 5, 95% CI 3 to 9), self reported physical function by four units (MD -4.35, 95% CI -7.77 to -0.94; NNT 6, 95% CI 3 to 22), pain by seven units (MD -6.59, 95% CI -10.71 to -2.48; NNT 5, 95% CI 3 to 8), and stiffness by 18 units (MD -18.34, 95% CI -35.75 to -0.93; NNT 3, 95% CI 2 to 24) more in the aquatic than the control groups. The SMD for muscle strength as measured by knee extension and hand grip was 0.63 standard deviations higher compared to the control group (SMD 0.63, 95% CI 0.20 to 1.05; NNT 4, 95% CI 3 to 12) and cardiovascular submaximal function improved by 37 meters on six-minute walk test (95% CI 4.14 to 69.92). Only two major outcomes, stiffness and muscle strength, met the 15% threshold for clinical relevance (improved by 27% and 37% respectively). Withdrawals were similar in the aquatic and control groups and adverse effects were poorly reported, with no serious adverse effects reported. Aquatic versus land-basedThere were no statistically significant differences between interventions for multidimensional function, self reported physical function, pain or stiffness: 0.91 units (95% CI -4.01 to 5.83), -5.85 units (95% CI -12.33 to 0.63), -0.75 units (95% CI -10.72 to 9.23), and two units (95% CI -8.88 to 1.28) respectively (all based on a 100-point scale), or in submaximal cardiorespiratory function (three seconds on a 100-meter walk test, 95% CI -1.77 to 7.77). We found a statistically significant difference between interventions for strength, favoring land-based training (2.40 kilo pascals grip strength, 95% CI 4.52 to 0.28). None of the outcomes in the aquatic versus land comparison reached clinically relevant differences of 15%. Withdrawals were similar in the aquatic and land groups and adverse effects were poorly reported, with no serious adverse effects in either group. Aquatic versus aquatic (Ai Chi versus stretching in the water, exercise in pool water versus exercise in sea water)Among the major outcomes the only statistically significant difference between interventions was for stiffness, favoring Ai Chi (1.00 on a 100-point scale, 95% CI 0.31 to 1.69).

AUTHORS' CONCLUSIONS

Low to moderate quality evidence relative to control suggests that aquatic training is beneficial for improving wellness, symptoms, and fitness in adults with fibromyalgia. Very low to low quality evidence suggests that there are benefits of aquatic and land-based exercise, except in muscle strength (very low quality evidence favoring land). No serious adverse effects were reported.

Fibromyalgia patients had normal distraction related pain inhibition but cognitive impairment reflected in caudate nucleus and hippocampus during the Stroop Color Word Test

The mechanisms causing cognitive problems in chronic pain patients are not well understood. We used the Stroop color word task (SCWT) to investigate distraction-induced analgesia, cognitive performance, and cerebral activation patterns in 29 fibromyalgia (FM) patients (mean age 49.8 years, range 25–64 years) and 31 healthy controls (HC) (mean age 46.3 years, range 20–63 years). In the first study, SCWT was used to investigate distraction-induced analgesia in FM patients. Two versions of the task were applied, one with only congruent color-word images and one with incongruent images. Pressure pain thresholds were assessed using a pressure algometer before, during, and following SCWT. In the second study, reaction times (RTs) were assessed and functional magnetic resonance imaging (fMRI) was used to investigate cerebral activation patterns in FM patients and HC during the SCWT. An event-related task mixing incongruent and congruent images was used. In study one, we found reduced pressure pain sensitivity during SCWT in both groups alike and no statistically significant differences were seen between the incongruent and congruent conditions. The study two revealed longer RTs during the incongruent compared to the congruent condition in both groups. FM patients had longer RTs than HC in both conditions. Furthermore, we found a significant interaction between group and congruency; that is, the group differences in RTs were more pronounced during the incongruent condition. This was reflected in a reduced activation of the caudate nucleus, lingual gyrus, temporal areas, and the hippocampus in FM patients compared to HC. In conclusion, we found normal pain inhibition during SWTC in FM patients. The cognitive difficulties seen in FM patients, reflected in longer RTs, were related to reduced activation of the caudate nucleus and hippocampus during incongruent SCWT, which most likely affected the mechanisms of cognitive learning in FM patients.

Can words heal? Using affect labeling to reduce the effects of unpleasant cues on symptom reporting

Processing unpleasant affective cues induces elevated momentary symptom reports, especially in persons with high levels of symptom reporting in daily life. The present study aimed to examine whether applying an emotion regulation strategy, i.e. affect labeling, can inhibit these emotion influences on symptom reporting. Student participants (N = 61) with varying levels of habitual symptom reporting completed six picture viewing trials of homogeneous valence (three pleasant, three unpleasant) under three conditions: merely viewing, emotional labeling, or content (non-emotional) labeling. Affect ratings and symptom reports were collected after each trial. Participants completed a motor inhibition task and self-control questionnaires as indices of their inhibitory capacities. Heart rate variability was also measured. Labeling, either emotional or non-emotional, significantly reduced experienced affect, as well as the elevated symptoms reports observed after unpleasant picture viewing. These labeling effects became more pronounced with increasing levels of habitual symptom reporting, suggesting a moderating role of the latter variable, but did not correlate with any index of general inhibitory capacity. Our findings suggest that using an emotion regulation strategy, such as labeling emotional stimuli, can reverse the effects of unpleasant stimuli on symptom reporting and that such strategies can be especially beneficial for individuals suffering from medically unexplained physical symptoms.

Changes in clinical pain in fibromyalgia patients correlate with changes in brain activation in the cingulate cortex in a response inhibition task

OBJECTIVE

The primary symptom of fibromyalgia is chronic, widespread pain; however, patients report additional symptoms including decreased concentration and memory. Performance-based deficits are seen mainly in tests of working memory and executive functioning. It has been hypothesized that pain interferes with cognitive performance; however, the neural correlates of this interference are still a matter of debate. In a previous, cross-sectional study, we reported that fibromyalgia patients (as compared with healthy controls) showed a decreased blood oxygen level dependent (BOLD) response related to response inhibition (in a simple Go/No-Go task) in the anterior/mid cingulate cortex, supplementary motor area, and right premotor cortex.

METHODS

Here in this longitudinal study, neural activation elicited by response inhibition was assessed again in the same cohort of fibromyalgia patients and healthy controls using the same Go/No-Go paradigm.

RESULTS

A decrease in percentage of body pain distribution was associated with an increase in BOLD signal in the anterior/mid cingulate cortex and the supplementary motor area, regions that have previously been shown to be "hyporeactive" in this cohort.

CONCLUSIONS

Our results suggest that the clinical distribution of pain is associated with the BOLD response elicited by a cognitive task. The cingulate cortex and the supplementary motor area are critically involved in both the pain system as well as the response inhibition network. We hypothesize that increases in the spatial distribution of pain might engage greater neural resources, thereby reducing their availability for other networks. Our data also point to the potential for, at least partial, reversibility of these changes.

Pain characteristics associated with the onset of disability in older adults: the maintenance of balance, independent living, intellect, and zest in the Elderly Boston Study

OBJECTIVES

To determine the effects of chronic pain on the development of disability and decline in physical performance over time in older adults.

DESIGN

Longitudinal cohort study with 18 months of follow-up.

SETTING

Urban and suburban communities.

PARTICIPANTS

Community-dwelling older adults aged 65 and older (N = 634).

MEASUREMENTS

Chronic pain assessment consisted of musculoskeletal pain locations and pain severity and pain interference according to the subscales of the Brief Pain Inventory. Disability was self-reported as any difficulty in mobility and basic and instrumental activities of daily living (ADLs, IADLs). Mobility performance was measured using the Short Physical Performance Battery (SPPB). Relationships between baseline pain and incident disability in 18 months were determined using risk ratios (RRs) from multivariable Poisson regression models.

RESULTS

Almost 65% of participants reported chronic musculoskeletal pain at baseline. New onset of mobility difficulty at 18 months was strongly associated with baseline pain distribution: 7% (no sites), 18% (1 site), 24% (multisite), and 39% (widespread pain, P-value for trend < .001). Similar graded effects were found for other disability measures. Elderly adults with multisite or widespread pain had at a risk of onset of mobility difficulty at least three times as great as that of their peers without pain after adjusting for disability risk factors (multisite pain: risk ratio (RR) = 2.95, 95% confidence interval (CI) 1.58-5.50; widespread pain: RR = 3.57, 95% CI = 1.71-7.48). Widespread pain contributed to decline in mobility performance (1-point decline in SPPB, RR = 1.47, 95% CI = 1.08-2.01). Similar associations were found for baseline pain interference predicting subsequent mobility decline and ADL and IADL disability. Weaker and less-consistent associations were observed with pain severity.

CONCLUSION

Older community-dwelling adults living with chronic pain in multiple musculoskeletal locations have a substantially greater risk for developing disability over time and for clinically meaningful decline in mobility performance than those without pain.

Enhanced pain-induced activity of pain-processing regions in a case-control study of episodic migraine

OBJECTIVE

The objective of this study was to identify brain regions having aberrant pain-induced activation in migraineurs, thereby gaining insight into particular aspects of pain processing that are atypical in migraineurs.

METHODS

Functional magnetic resonance imaging assessed whole brain responses to painful heat in 24 adult episodic migraineurs who were at least 48 hours pain free and 27 healthy controls. Regions differentially activated in migraineurs compared to controls were identified. Activation intensities in these regions were correlated with headache frequency, number of migraine years, and time to next migraine attack.

RESULTS

Migraineurs had greater pain-induced activation of lentiform nucleus, fusiform gyrus, subthalamic nucleus, hippocampus, middle cingulate cortex, premotor cortex, somatosensory cortex, and dorsolateral prefrontal cortex, and less activation in precentral gyrus and superior temporal gyrus. There were significant correlations between activation strength and headache frequency for middle cingulate (r = 0.627, p = 0.001), right dorsolateral prefrontal cortex (r = 0.568, p = 0.004), left fusiform gyrus (r = 0.487, p = 0.016), left precentral gyrus (r = 0.415, p = 0.044), and left hippocampus (r = 0.404, p = 0.050) and with number of migraine years for left fusiform gyrus (r = 0.425, p = 0.038). There were no significant correlations between activation strength and time to next migraine attack.

CONCLUSIONS

The majority of regions with enhanced pain-induced activation in headache-free migraineurs participate in cognitive aspects of pain perception such as attending to pain and pain memory. Enhanced cognitive pain processing by migraineurs might reflect cerebral hypersensitivity related to high expectations and hypervigilance for pain.

Brain functional connectivity and morphology changes in medication-overuse headache: Clue for dependence-related processes?

BACKGROUND

Several imaging studies have identified localized anatomical and functional brain changes in medication-overuse headache (MOH).

OBJECTIVE

The objective of this article is to evaluate whole-brain functional connectivity at rest together with voxel-based morphometry in MOH patients, in comparison with episodic migraine (EM) patients and healthy controls (HCs).

METHODS

Anatomical MRI and resting-state functional MRI scans were obtained in MOH patients (n = 17 and 9, respectively), EM patients (n = 18 and 15, respectively) and HCs (n = 17 and 17). SPM8 was used to analyze voxel-based morphometry and seed (left precuneus) to voxel connectivity data in the whole brain.

RESULTS

Functional connectivity at rest was altered in MOH patients. Connectivity was decreased between precuneus and regions of the default-mode network (frontal and parietal cortices), but increased between precuneus and hippocampal/temporal areas. These functional modifications were not accompanied by significant gross morphological changes. Furthermore, connectivity between precuneus and frontal areas in MOH was negatively correlated with migraine duration and positively correlated with self-evaluation of medication dependence. Gray matter volumes of frontal regions, precuneus and hippocampus were also negatively related to migraine duration. Functional connectivity within the default-mode network appeared to predict anxiety scores of MOH patients while gray matter volumes in this network predicted their depression scores.

CONCLUSIONS

Our data suggest that MOH is associated with functional alterations within intrinsic brain networks rather than with macrostructural changes. They also support the view that dependence-related processes might play a prominent role in its development and maintenance.

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.

Implicit memory function in fibromyalgia syndrome

The study investigated implicit memory function in fibromyalgia syndrome (FMS) and its association with clinical parameters. Implicit memory refers to the influence of past experience on current behavior without conscious awareness of these experiences. Eighteen FMS patients and 25 healthy individuals accomplished a word-stem completion task. As possible factors mediating the expected impairment, pain severity, emotional disorders, and medication were taken into account. The patients displayed markedly reduced task performance and higher levels of depression and anxiety. Among the clinical features, pain severity was most closely associated with performance, whereas depression, anxiety, and medication showed only a minor impact. The study documented reduced implicit memory function in FMS. In contrast to former findings on impaired performance of FMS patients on classical memory tests, lower implicit memory function cannot be ascribed to motivational deficits. Instead, the aberrances may relate to functional inference between central nervous nociceptive activity and cognitive processing.

Pain is associated with short leukocyte telomere length in women with fibromyalgia

Telomere length, considered a measure of biological aging, is linked to morbidity and mortality. Psychosocial factors associated with shortened telomeres are also common in chronic pain; yet, little is known about telomere length in pain populations. Leukocyte telomere length was evaluated in 66 women with fibromyalgia and 22 healthy female controls. Participants completed questionnaires and a subgroup of fibromyalgia patients underwent quantitative sensory testing (QST; n = 12) and neuroimaging (n = 12). Telomere length was measured using the quantitative polymerase chain reaction method. Although patients had shorter telomere length than controls, the difference was not statistically significant. However, higher levels of pain within fibromyalgia were associated with shorter telomere length (P = .039). When pain and depression were combined, patients categorized as high-pain/high-depression had an age-adjusted telomere length 265 base pairs shorter than those with low-pain/low-depression (P = .043), a difference consistent with approximately 6 years of chronological aging. In the subset tested, telomere length was also related to pain threshold and pain sensitivity, as well as gray matter volume, such that patients with shorter telomeres were more sensitive to evoked pain and had less gray matter in brain regions associated with pain processing (eg, primary somatosensory cortex). These preliminary data support a relationship between pain and telomere length.

PERSPECTIVE

Our findings support a link between premature cellular aging and chronic pain. These preliminary data imply that chronic pain is a more serious condition than has typically been recognized in terms of bodily aging.

Cognitive performance in women aged 50 years and older with and without fibromyalgia

OBJECTIVES

Persons with fibromyalgia (FM) report having cognitive dysfunction. Neuropsychological performance was compared across a variety of domains in 43 women with FM (Mage = 63 years) and in 44 women without FM (Mage = 65 years).

METHOD

Measures included explicit memory (Consortium to Establish a Registry for Alzheimer's Disease [CERAD] immediate/delayed recall, delayed recognition), aspects of executive function including interference/inhibition (Stroop Color/Word test), working memory (Digit Span Forward/Backward), set-shifting/complex sequencing (Trails B), monitoring (verbal fluency: naming animals), processing speed (Trails A, Digit Symbol Substitution Coding), and problem solving (Everyday Problems Test).

RESULTS

Women with FM performed more poorly than controls on executive function (Stroop Color/Word) and one processing speed measure (Digit Symbol Substitution Coding).

DISCUSSION

Results partly support altered cognitive function in FM. Mixed findings across cognitive domains among individuals with or without FM is consistent with the literature and suggest that factors beyond those typically controlled for (e.g., heterogeneity in FM) may be influencing findings. Future research is warranted.

Fibromyalgia syndrome: etiology, pathogenesis, diagnosis, and treatment

Fibromyalgia syndrome is mainly characterized by pain, fatigue, and sleep disruption. The etiology of fibromyalgia is still unclear: if central sensitization is considered to be the main mechanism involved, then many other factors, genetic, immunological, and hormonal, may play an important role. The diagnosis is typically clinical (there are no laboratory abnormalities) and the physician must concentrate on pain and on its features. Additional symptoms (e.g., Raynaud's phenomenon, irritable bowel disease, and heat and cold intolerance) can be associated with this condition. A careful differential diagnosis is mandatory: fibromyalgia is not a diagnosis of exclusion. Since 1990, diagnosis has been principally based on the two major diagnostic criteria defined by the ACR. Recently, new criteria have been proposed. The main goals of the treatment are to alleviate pain, increase restorative sleep, and improve physical function. A multidisciplinary approach is optimal. While most nonsteroidal anti-inflammatory drugs and opioids have limited benefit, an important role is played by antidepressants and neuromodulating antiepileptics: currently duloxetine (NNT for a 30% pain reduction 7.2), milnacipran (NNT 19), and pregabalin (NNT 8.6) are the only drugs approved by the US Food and Drug Administration for the treatment of fibromyalgia. In addition, nonpharmacological treatments should be associated with drug therapy.

Self-ratings of higher olfactory acuity contrast with reduced olfactory test results of fibromyalgia patients

BACKGROUND

Self-reports of fibromyalgia (FM) patients about an enhanced olfactory acuity have been used to characterize them as persons with a general increased sensitivity to sensory input consistent with a central sensitization. However, as reduced activations in some brain areas also seem to accompany FM, a multisensory hypersensitivity is not a necessary consequence.

METHODS

FM patients meeting ARA (American Rheumatism Association) criteria (16 women and one man, aged 23-56 years, spontaneous pain 32-91 mm visual analog scale [VAS], 14-18 tender points with a pressure pain threshold of 1.5±0.7 kg/cm(2)) received an olfactory test (Sniffn' Sticks) to assess their odor thresholds to n-butanol and their ability to discriminate and identify odors. Healthy controls were 14 age-matched women and one man.

RESULTS

Patients had poorer odor identification than controls (14.6±1.3 vs. 15.5±0.6; p<0.05) but did not differ in odor thresholds or odor discrimination. This test result contrasted with the patients' self-ratings of their olfactory sensitivity as higher than average.

CONCLUSIONS

The perception of FM patients as being multisensory hypersensitive is not supported by present results. In contrast to the subjects' self-ratings, measurements of olfactory function showed a slightly reduced odor identification, with a by-and-large normal performance.

The use of functional neuroimaging to evaluate psychological and other non-pharmacological treatments for clinical pain

A large number of studies have provided evidence for the efficacy of psychological and other non-pharmacological interventions in the treatment of chronic pain. While these methods are increasingly used to treat pain, remarkably few studies focused on the exploration of their neural correlates. The aim of this article was to review the findings from neuroimaging studies that evaluated the neural response to distraction-based techniques, cognitive behavioral therapy (CBT), clinical hypnosis, mental imagery, physical therapy/exercise, biofeedback, and mirror therapy. To date, the results from studies that used neuroimaging to evaluate these methods have not been conclusive and the experimental methods have been suboptimal for assessing clinical pain. Still, several different psychological and non-pharmacological treatment modalities were associated with increased pain-related activations of executive cognitive brain regions, such as the ventral- and dorsolateral prefrontal cortex. There was also evidence for decreased pain-related activations in afferent pain regions and limbic structures. If future studies will address the technical and methodological challenges of today's experiments, neuroimaging might have the potential of segregating the neural mechanisms of different treatment interventions and elucidate predictive and mediating factors for successful treatment outcomes. Evaluations of treatment-related brain changes (functional and structural) might also allow for sub-grouping of patients and help to develop individualized treatments.