Altered cerebral response to noxious heat stimulation in patients with somatoform pain disorder

Changes in interoceptive accuracy related to emotional interference in somatic symptom disorder

OBJECTIVE

The somatic symptom disorder (SSD) is characterized by one or more distressing or disabling somatic symptoms accompanied by an excessive amount of time, energy and emotion related to the symptoms. These manifestations of SSD have been linked to alterations in perception and appraisal of bodily signals. We hypothesized that SSD patients would exhibit changes in interoceptive accuracy (IA), particularly when emotional processing is involved.

METHODS

Twenty-three patients with SSD and 20 healthy controls were recruited. IA was assessed using the heartbeat perception task. The task was performed in the absence of stimuli as well as in the presence of emotional interference, i.e., photographs of faces with an emotional expression. IA were examined for correlation with measures related to their somatic symptoms, including resting-state heart rate variability (HRV).

RESULTS

There was no significant difference in the absolute values of IA between patients with SSD and healthy controls, regardless of the condition. However, the degree of difference in IA without emotional interference and with neutral facial interference was greater in patients with SSD than in healthy controls (p = 0.039). The IA of patients with SSD also showed a significant correlation with low-frequency HRV (p = 0.004) and high-frequency HRV (p = 0.007).

CONCLUSION

SSD patients showed more significant changes in IA when neutral facial interference was given. These results suggest that bodily awareness is more affected by emotionally ambiguous stimuli in SSD patients than in healthy controls.

Effects of Methylphenidate on Somatic Symptoms and Brain Functional Connectivity in Adolescents with Attention Deficit Hyperactivity Disorder: A Pilot Study

Objective

This study aimed to evaluate whether somatic symptoms in adolescents with attention deficit hyperactivity disorder (ADHD) are associated with a dissociative pattern of functional connectivity (FC) within the default mode network (DMN) and whether methylphenidate administration can improve clinical and somatic symptoms. We also evaluated whether the improvement of somatic symptoms is associated with increased FC within the DMN in response to methylphenidate treatment.

Methods

Fifteen male adolescents with somatic symptoms of ADHD and 15 male adolescents with ADHD without somatic symptoms were included. At baseline and after 6 months of methylphenidate treatment, all adolescents were asked to complete questionnaires for the Korean version of the Dupaul’s ADHD rating scale, the symptom checklist-90- revised-somatization subscales, the Beck Depression Inventory, and the Beck Anxiety Inventory. Additionally, a resting-state functional magnetic resonance imaging scan was conducted.

Results

Methylphenidate treatment improved clinical and somatic symptoms in adolescents with ADHD. In addition, it increased brain FC within the DMN from the posterior cingulate cortex (posterior DMN) to the middle prefrontal cortex (anterior DMN). The improvement of somatic symptoms was associated with FC within the DMN from the posterior cingulate cortex to the middle prefrontal cortex in ADHD adolescents with somatic symptoms.

Conclusion

Methylphenidate increased brain FC between the anterior and posterior DMN. The improvement of somatic symptoms in adolescents with ADHD was associated with FC within the DMN. The DMN in adolescents with ADHD seems to be associated with the severity of the clinical and somatic symptoms of ADHD.

Functional seizures are associated with cerebrovascular disease and functional stroke is more common in patients with functional seizures than epileptic seizures

PURPOSE

To characterize the relationship between functional seizures (FSe), cerebrovascular disease (CVD), and functional stroke.

METHOD

A retrospective case-control study of 189 patients at a single large tertiary medical center. We performed a manual chart review of medical records of patients with FSe or epileptic seizures (ES), who also had ICD code evidence of CVD. The clinical characteristics of FSe, ES, CVD, and functional stroke were recorded. Logistic regression and Welch's t-tests were used to evaluate the differences between the FSe and ES groups.

RESULTS

Cerebrovascular disease was confirmed in 58.7% and 87.6% of patients with FSe or ES through manual chart review. Stroke was significantly more common in patients with ES (76.29%) than FSe (43.48%) (p = 4.07 × 10^-6). However, compared to nonepileptic controls FSe was associated with both CVD (p < 0.0019) and stroke (p < 6.62 × 10^-10). Functional stroke was significantly more common in patients with FSe (39.13%) than patients with ES (4.12%) (p = 4.47 × 10^-9). Compared to patients with ES, patients with FSe were younger (p = 0.00022), more likely to be female (p = 0.00040), and more likely to have comorbid mental health needs including anxiety (p = 1.06 × 10^-6), PTSD or history of trauma (e.g., sexual abuse) (p = 1.06 × 10^-13), and bipolar disorder (p = 0.0011).

CONCLUSION

Our results confirm the initial observation of increased CVD in patients with FSe and further suggest that patients with FSe may be predisposed to developing another functional neurological disorder (FND) (i.e., functional stroke). We speculate that this may be due to shared risk factors and pathophysiological processes that are common to various manifestations of FND.

Altered functional connectivity of the amygdala in Crohn's disease

Crohn's disease (CD), a chronic inflammatory bowel disease, involved in brain structural and functional changes, including the amygdala. Amygdala is a key structure in the limbic system and its related circuits are implicated in processing of emotion, pain and sensory. However, limited study of the amygdala is elucidated in CD. This study mainly investigated altered functional connectivity (FC) of the amygdala in CD patients during resting-state. Magnetic resonance imaging scans were acquired from 42 CD patients and 35 healthy controls (HCs). Whole amygdala bilaterally were selected as regions of interest (ROIs). Voxel-based morphometry and FC methods were applied to investigate the differences of structure or intrinsic connectivity of the amygdala between the two groups, separately. Pearson correlations were performed to explore relationships between the clinical characteristics and neuroimaging findings in CD patients. Based on the whole amygdala bilaterally as ROIs, compared with HCs, CD patients showed no statistical differences of grey matter destiny but exhibited decreased FC between the amygdala and insula, parahippocampus, as well as anterior middle cingulate cortex/dorsal anterior cingulate cortex. CD patients had negative correlation between the disease duration and amygdala-insula connectivity. In the patient group, patients with higher anxiety or depression scores revealed increased FC of the amygdala with thalamus and orbitofrontal cortex. Our results reveal that aberrant FC of the amygdala may be involved in processing of visceral pain and sensation, and emotion in CD. These findings may further enhance the understanding of neural mechanisms of CD.

Somatization Symptoms Regulate Emotional Memory Bias in Adolescents With Major Depressive Disorder

Objective: Somatization symptoms are commonly comorbid with depression. Furthermore, people with depression and somatization have a negative memory bias. We investigated the differences in emotional memory among adolescent patients with depressive disorders, with and without functional somatization symptoms (FSS). Methods: We recruited 30 adolescents with depression and FSS, 38 adolescents with depression but without FSS, and 38 healthy participants. Emotional memory tasks were conducted to evaluate the emotional memory of the participants in the three groups. The clinical symptoms were evaluated using the Hamilton Depression Rating Scale (HDRS) and the Children's Somatization Inventory (CSI). Results: The valence ratings and recognition accuracy rates for positive and neutral images of adolescent patients were significantly lower than those of the control group (F = 12.208, P < 0.001; F = 6.801, P < 0.05; F = 14.536, P < 0.001; F = 6.306, P < 0.05, respectively); however, the recognition accuracy rate for negative images of adolescent patients of depression without FSS was significantly lower than that of patients with FSS and control group participants (F = 10.316, P < 0.001). These differences persisted after controlling for HDRS scores. The within-group analysis revealed that patients of depression with FSS showed significantly higher recognition accuracy rates for negative images than the other types (F = 5.446, P < 0.05). The recognition accuracy rate for negative images was positively correlated with CSI scores (r = 0.352, P < 0.05). Conclusion: Therefore, emotional memory impairment exists in adolescent patients of depression and FSS are associated with negative emotional memory retention.

The CSF-Contacting Nucleus Receives Anatomical Inputs From the Cerebral Cortex: A Combination of Retrograde Tracing and 3D Reconstruction Study in Rat

Objective

This study aimed to investigate the direct monosynaptic projections from cortical functional regions to the cerebrospinal fluid (CSF)-contacting nucleus for understanding the functions of the CSF-contacting nucleus.

Methods

The Sprague-Dawley rats received cholera toxin B subunit (CB) injections into the CSF-contacting nucleus. After 7-10 days of survival time, the rats were perfused, and the whole brain and spinal cord were sliced under a freezing microtome at 40 μm. All sections were treated with the CB immunofluorescence reaction. The retrogradely labeled neurons in different cortical areas were revealed under a confocal microscope. The distribution features were further illustrated under 3D reconstruction.

Results

The retrogradely labeled neurons were identified in the olfactory, orbital, cingulate, insula, retrosplenial, somatosensory, motor, visual, auditory, association, rhinal, and parietal cortical areas. A total of 12 functional areas and 34 functional subregions showed projections to the CSF-contacting nucleus in different cell intensities.

Conclusion

According to the connectivity patterns, we conclude that the CSF-contacting nucleus participates in cognition, emotion, pain, visceral activity, etc. The present study firstly reveals the cerebral cortex→CSF-contacting nucleus connections, which implies the multiple functions of this special nucleus in neural and body fluid regulations.

Aberrant Thalamic-Centered Functional Connectivity in Patients with Persistent Somatoform Pain Disorder

PURPOSE

Recent task-based fMRI studies have shown that Persistent Somatoform Pain Disorder (PSPD) patients demonstrated aberrant activity in a wide range of brain regions associated with sensation, cognition and emotion. However, these specific task-based studies could not clearly uncover the alterations in the spontaneous brain networks that were associated with the general pain-related symptoms in PSPD.

PATIENTS AND METHODS

In the present study, 13 PSPD patients and 23 matched healthy controls (HCs) were enrolled. Resting state and 3D structural imaging data were collected during magnetic resonance imaging (MRI) scans. Ninety regions of interest (ROIs) were selected from the automated anatomical labeling (AAL) template. The functional connectivity toolbox "CONN" was used to calculate the functional connectivity (FC) coefficients.

RESULTS

Our results showed that PSPD patients exhibited increased FCs between the left thalamus and the right amygdala, the right hippocampus, and multiple sub-regions of the occipital lobe when compared to HCs. Correlation analysis revealed a negative correlation between the left thalamus-right amygdala FC and the level of anxiety in PSPD patients.

CONCLUSION

These findings suggest that the altered FC between thalamus and amygdala may be the neural mechanisms underlying the pain-related anxiety in PSPD.

When it hurts even more: The neural dynamics of pain and interpersonal emotions

OBJECTIVE

Chronic pain is highly prevalent among patients with mood, anxiety, personality, and somatic symptom disorders; and patients with chronic pain often suffer from persistent interpersonal distress. However, the neural mechanisms underlying this phenomenon and its possible role in the etiology of chronic pain are not yet understood. Based on our Developmental Theory of Centralized/Somatoform Pain, and prior research suggesting the existence of a shared neural system subserving interpersonal emotions and pain, we aimed to identify the neural basis for modulation of pain by feelings of interpersonal rejection and the role of the early interpersonal environment in development of this shared neural system.

METHODS

During fMRI scanning, 22 healthy participants received moderately painful thermal stimuli in 3 interpersonal contexts: Acceptance, Rejection, and Reacceptance (modified Cyberball paradigm). Early interpersonal environment was assessed using the Parental Bonding Instrument.

RESULTS

Interpersonal context modulated activity in pain neural systems during rejection and during accepting interactions with previously rejecting others. Moreover, the subjective perception of rejection, even when rejection was not occurring, correlated positively with reported pain severity and neural activity in the insula. The magnitude of neural modulation in pain circuits by feelings of rejection was associated with the quality of early interpersonal experience with caregivers.

CONCLUSIONS

Results suggest that interpersonal emotions play an important role in the development and functioning of the pain system, supporting our Developmental Theory of predisposition to chronic centralized pain. These findings have direct implications for clinical practice, including the importance of treating interpersonal distress to alleviate pain.

Behavioral Heterogeneity in Relation with Brain Functional Networks in Young Children

This study aimed to identify distinct behavioral profiles in a population-based sample of 654 4-year-old children and characterize their relationships with brain functional networks using resting-state functional magnetic resonance imaging data. Young children showed 7 behavioral profiles, including a super healthy behavioral profile with the lowest scores across all Child Behavior CheckList (CBCL) subscales (G1) and other 6 behavioral profiles, respectively with pronounced withdrawal (G2), somatic complaints (G3), anxiety and withdrawal (G4), somatic complaints and withdrawal (G5), the mixture of emotion, withdrawal, and aggression (G6), and attention (G7) problems. Compared with children in G1, children with withdrawal shared abnormal functional connectivities among the sensorimotor networks. Children in emotionally relevant problems shared the common pattern among the attentional and frontal networks. Nevertheless, children in sole withdrawal problems showed a unique pattern of connectivity alterations among the sensorimotor, cerebellar, and salience networks. Children with somatic complaints showed abnormal functional connectivities between the attentional and subcortical networks, and between the language and posterior default mode networks. This study provides novel evidence on the existence of behavioral heterogeneity in early childhood and its associations with specific functional networks that are clinically relevant phenotypes for mental illness and are apparent from early childhood.

Altered neural oscillations within and between sensorimotor cortex and parietal cortex in chronic jaw pain

Pain perception is associated with priming of the motor system and the orienting of attention in healthy adults. These processes correspond with decreases in alpha and beta power in the sensorimotor and parietal cortices. The goal of the present study was to determine whether these findings extend to individuals with chronic pain. Individuals with chronic jaw pain and pain-free controls anticipated and experienced a low pain or a moderate pain-eliciting heat stimulus. Although stimuli were calibrated for each subject, stimulus temperature was not different between groups. High-density EEG data were collected during the anticipation and heat stimulation periods and were analyzed using independent component analyses, EEG source localization, and measure projection analyses. Direct directed transfer function was also estimated to identify frequency specific effective connectivity between regions. Between group differences were most evident during the heat stimulation period. We report three novel findings. First, the chronic jaw pain group had a relative increase in alpha and beta power and a relative decrease in theta and gamma power in sensorimotor cortex. Second, the chronic jaw pain group had a relative increase in power in the alpha and beta bands in parietal cortex. Third, the chronic jaw pain group had less connectivity strength in the beta and gamma bands between sensorimotor cortex and parietal cortex. Our findings show that the effect of chronic pain attenuates rather than magnifies neural responses to heat stimuli. We interpret these findings in the context of system-level changes in intrinsic sensorimotor and attentional circuits in chronic pain.

Hyperexcitability of Cortical Oscillations in Patients with Somatoform Pain Disorder: A Resting-State EEG Study

Patients with somatoform pain disorder (SPD) suffer from somatic pain that cannot be fully explained by specific somatic pathology. While the pain experience requires the integration of sensory and contextual processes, the cortical oscillations have been suggested to play a crucial role in pain processing and integration. The present study is aimed at identifying the abnormalities of spontaneous cortical oscillations among patients with SPD, thus for a better understanding of the ongoing brain states in these patients. Spontaneous electroencephalography data during a resting state with eyes open were recorded from SPD patients and healthy controls, and their cortical oscillations as well as functional connectivity were compared using both electrode-level and source-level analysis. Compared with healthy controls, SPD patients exhibited greater resting-state alpha oscillations (8.5-12.5 Hz) at the parietal region, as reflected by both electrode-level spectral power density and exact low-resolution brain electromagnetic tomography (eLORETA) cortical current density. A significant correlation between parietal alpha oscillation and somatization severity was observed in SPD patients, after accounting for the influence of anxiety and depression. Functional connectivity analysis further revealed a greater frontoparietal connectivity of the resting-state alpha oscillations in SPD patients, which was indexed by the coherence between pairs of electrodes and the linear connectivity between pairs of eLORETA cortical sources. The enhanced resting-state alpha oscillation in SPD patients could be relevant with attenuated sensory information gating and excessive integration of pain-related information, while the enhanced frontoparietal connectivity could be reflecting their sustained attention to bodily sensations and hypervigilance to somatic sensations.

Brain Functional Connectivity in Patients With Somatic Symptom Disorder

OBJECTIVE

The aim of the study was to evaluate whether individuals with somatic symptom disorder (SSD) display increased resting-state functional connectivity (FC) within and between the sensorimotor network (SMN), default mode network (DMN), salience network, and dorsal attention network (DAN).

METHODS

Eighteen patients with SSD and 20 age- and sex-matched healthy control participants underwent resting-state functional magnetic resonance imaging. We used a seed-based correlation approach for the four brain networks.

RESULTS

Patients with SSD had higher scores on the Somato-Sensory Amplification Scale (z = 5.22, p < .001) and Symptom Checklist-90-Revised-Somatization (z = 4.94, p < .001) and greater FC within the SMN, DMN, and salience network than healthy control participants. Patients with SSD also had increased FC between the SMN and DMN, SMN and salience network, SMN and DAN, and salience network and DAN (t = 5.10-7.47, all false discovery rate q < .05). The Somato-Sensory Amplification Scale scores correlated with FC between the SMN and salience network and between the SMN and DAN (r = .61-.82, all p < .003).

CONCLUSIONS

Based on the results of the FC analysis between the SMN and salience network, we suggest that SSD may be associated with alterations of sensory-discriminative processing of pain and other somatic symptoms, which is influenced by affective processing. Based on the results of the FC analysis of the SMN and DAN, we suggest that patients with SSD have a deficit in attention, leading to misperception of external stimuli and failure to regulate bodily functions aimed at interactions with external stimuli.

Structural alterations in functional neurological disorder and related conditions: a software and hardware problem?

Functional neurological (conversion) disorder (FND) is a condition at the interface of neurology and psychiatry. A “software” vs. “hardware” analogy describes abnormal neurobiological mechanisms occurring in the context of intact macroscopic brain structure. While useful for explanatory and treatment models, this framework may require more nuanced considerations in the context of quantitative structural neuroimaging findings in FND. Moreover, high co-occurrence of FND and somatic symptom disorders (SSD) as defined in DSM-IV (somatization disorder, somatoform pain disorder, and undifferentiated somatoform disorder; referred to as SSD for brevity in this article) raises the possibility of a partially overlapping pathophysiology. In this systematic review, we use a transdiagnostic approach to review and appraise the structural neuroimaging literature in FND and SSD. While larger sample size studies are needed for definitive characterization, this article highlights that individuals with FND and SSD may exhibit sensorimotor, prefrontal, striatal-thalamic, paralimbic, and limbic structural alterations. The structural neuroimaging literature is contextualized within the neurobiology of stress-related neuroplasticity, gender differences, psychiatric comorbidities, and the greater spectrum of functional somatic disorders. Future directions that could accelerate the characterization of the pathophysiology of FND and DSM-5 SSD are outlined, including “disease staging” discussions to contextualize subgroups with or without structural changes. Emerging neuroimaging evidence suggests that some individuals with FND and SSD may have a “software” and “hardware” problem, although if structural alterations are present the neural mechanisms of functional disorders remain distinct from lesional neurological conditions. Furthermore, it remains unclear whether structural alterations relate to predisposing vulnerabilities or consequences of the disorder.

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Transdiagnostic systematic review of structural MRI studies in FND and SSD

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Sensorimotor-striatothalamic-limbic-paralimbic circuits implicated in both conditions.

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Some small sample size FND studies did not show group-level structural alterations.

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MRI alterations may relate to risk factors, compensatory changes or disease mechanisms.

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Early-phase discussion on disease-staging algorithms outlined as a future direction.

Functional brain activity during motor control and pain processing in chronic jaw pain

Changes in brain function in chronic pain have been studied using paradigms that deliver acute pain-eliciting stimuli or assess the brain at rest. Although motor disability accompanies many chronic pain conditions, few studies have directly assessed brain activity during motor function in individuals with chronic pain. Using chronic jaw pain as a model, we assessed brain activity during a precisely controlled grip force task and during a precisely controlled pain-eliciting stimulus on the forearm. We used multivariate analyses to identify regions across the brain whose activity together best separated the groups. We report 2 novel findings. First, although the parameters of grip force production were similar between the groups, the functional activity in regions including the prefrontal cortex, insula, and thalamus best separated the groups. Second, although stimulus intensity and pain perception were similar between the groups, functional activity in brain regions including the dorsal lateral prefrontal cortex, rostral ventral premotor cortex, and inferior parietal lobule best separated the groups. Our observations suggest that chronic jaw pain is associated with changes in how the brain processes motor and pain-related information even when the effector producing the force or experiencing the pain-eliciting stimulus is distant from the jaw. We also demonstrate that motor tasks and multivariate analyses offer alternative approaches for studying brain function in chronic jaw pain.

Dopaminergic modulation of pain signals in the medial prefrontal cortex: Challenges and perspectives

Chronic pain is a massive socieoeconomic burden and is often refractory to treatment. To devise novel therapeutic interventions, it is important to understand in detail the processing of pain signals in the brain. Recent studies have revealed shared features between the brain's reward and pain systems. Dopamine (DA) is a key neuromodulator in the mesocorticolimbic system that has been implicated not only in motivated behaviours, reinforcement learning and reward processing, but also in the pain axis. The medial prefrontal cortex (mPFC) is an important region for mediating executive functions including attention, judgement, and learning. Studies have revealed that the mPFC undergoes plasticity during the development of chronic pain. The mPFC receives dopaminergic input from the ventral tegmental area (VTA), and stimulation of these inputs has been shown to modulate the plasticity of the mPFC and anxiety and aversive behaviour. Here, we review the role of the mPFC and its dopaminergic modulation in chronic pain.

Morphine Attenuates fNIRS Signal Associated With Painful Stimuli in the Medial Frontopolar Cortex (medial BA 10)

Functional near infrared spectroscopy (fNIRS) is a non-invasive optical imaging method that provides continuous measure of cortical brain functions. One application has been its use in the evaluation of pain. Previous studies have delineated a deoxygenation process associated with pain in the medial anterior prefrontal region, more specifically, the medial Brodmann Area 10 (BA 10). Such response to painful stimuli has been consistently observed in awake, sedated and anesthetized patients. In this study, we administered oral morphine (15 mg) or placebo to 14 healthy male volunteers with no history of pain or opioid abuse in a crossover double blind design, and performed fNIRS scans prior to and after the administration to assess the effect of morphine on the medial BA 10 pain signal. Morphine is the gold standard for inhibiting nociceptive processing, most well described for brain effects on sensory and emotional regions including the insula, the somatosensory cortex (the primary somatosensory cortex, S1, and the secondary somatosensory cortex, S2), and the anterior cingulate cortex (ACC). Our results showed an attenuation effect of morphine on the fNIRS-measured pain signal in the medial BA 10, as well as in the contralateral S1 (although observed in a smaller number of subjects). Notably, the extent of signal attenuation corresponded with the temporal profile of the reported plasma concentration for the drug. No clear attenuation by morphine on the medial BA 10 response to innocuous stimuli was observed. These results provide further evidence for the role of medial BA 10 in the processing of pain, and also suggest that fNIRS may be used as an objective measure of drug-brain profiles independent of subjective reports.

Increased coherence-based regional homogeneity in resting-state patients with first-episode, drug-naive somatization disorder

BACKGROUND

Abnormal neural activity has been observed in patients with somatization disorder (SD), especially in brain regions of the default-mode network (DMN). In this study, a coherence-based regional homogeneity (Cohe-ReHo) approach was used to detect abnormal regional synchronization in patients with SD, which might be used to differentiate the patients from the controls.

METHODS

We recruited 25 patients with SD and 28 healthy controls. The imaging data of the participants were analyzed using the Cohe-ReHo approach. LIBSVM (a library for support vector machines) was utilized to verify whether abnormal Cohe-ReHo values could be applied to separate patients with SD from healthy controls.

RESULTS

Compared with healthy controls, patients with SD showed an increased Cohe-ReHo in the left medial prefrontal cortex/anterior cingulate cortex (MPFC/ACC) (t = 5.5017, p < 0.001). No correlations were detected between the increased Cohe-ReHo values and clinical variables of the patients. The Cohe-ReHo values in the left MPFC/ACC could be applied to distinguish patients from controls with a sensitivity and a specificity of 84.00% and 85.71%, respectively.

CONCLUSIONS

An increased Cohe-ReHo was observed in the anterior DMN of the patients and could be applied as a marker to distinguish patients from healthy controls. These results highlighted the importance of the DMN in the pathophysiology of SD.

Fronto-Insular Connectivity during Pain Distraction Is Impaired in Patients with Somatoform Pain

BACKGROUND AND PURPOSE

Somatoform pain disorder is characterized by chronic pain and various psychological symptoms including increased attention to mental and physical processes. Given that the medial prefrontal cortex (mPFC) of the default mode network (DMN) and the anterior insula of the salience network are critically involved in intrinsic and attentional processes, we investigated the involvement of these networks during the distraction from physical pain in somatoform pain patients.

METHODS

During painful and nonpainful heat stimulation, attentional distraction from physical processes was modulated with a Stroop task. Thirteen patients were investigated with functional magnetic resonance imaging (fMRI) and compared to 13 controls. Main outcomes were spatial maps of coherent fMRI activity based on independent component analysis and functional connectivity (FC) resulting from psychophysiological interaction analysis.

RESULTS

Behavioral pain intensity ratings were reduced during the distraction task in both groups. At brain level, we found deviant network activities in the DMN (particularly in the mPFC) and in the salience network (bilaterally in the anterior insula) in patients. During pain stimulation, Stroop-induced distraction decreased the FC between the mPFC and anterior insula in controls but not in patients.

CONCLUSIONS

Modulating the FC between the mPFC and the insula may be highly relevant for shifting the attention away from external stimuli, including nociceptive input. The observed alterations in somatoform pain patients may foster new strategies in cognitive behavioral training tools for these patients.

Using prerecorded hemodynamic response functions in detecting prefrontal pain response: a functional near-infrared spectroscopy study

Currently, there is no method for providing a nonverbal objective assessment of pain. Recent work using functional near-infrared spectroscopy (fNIRS) has revealed its potential for objective measures. We conducted two fNIRS scans separated by 30 min and measured the hemodynamic response to the electrical noxious and innocuous stimuli over the anterior prefrontal cortex (aPFC) in 14 subjects. Based on the estimated hemodynamic response functions (HRFs), we first evaluated the test-retest reliability of using fNIRS in measuring the pain response over the aPFC. We then proposed a general linear model (GLM)-based detection model that employs the subject-specific HRFs from the first scan to detect the pain response in the second scan. Our results indicate that fNIRS has a reasonable reliability in detecting the hemodynamic changes associated with noxious events, especially in the medial portion of the aPFC. Compared with a standard HRF with a fixed shape, including the subject-specific HRFs in the GLM allows for a significant improvement in the detection sensitivity of aPFC pain response. This study supports the potential application of individualized analysis in using fNIRS and provides a robust model to perform objective determination of pain perception.

Brodmann area 10: Collating, integrating and high level processing of nociception and pain

Multiple frontal cortical brain regions have emerged as being important in pain processing, whether it be integrative, sensory, cognitive, or emotional. One such region, Brodmann Area 10 (BA 10), is the largest frontal brain region that has been shown to be involved in a wide variety of functions including risk and decision making, odor evaluation, reward and conflict, pain, and working memory. BA 10, also known as the anterior prefrontal cortex, frontopolar prefrontal cortex or rostral prefrontal cortex, is comprised of at least two cytoarchitectonic sub-regions, medial and lateral. To date, the explicit role of BA 10 in the processing of pain hasn't been fully elucidated. In this paper, we first review the anatomical pathways and functional connectivity of BA 10. Numerous functional imaging studies of experimental or clinical pain have also reported brain activations and/or deactivations in BA 10 in response to painful events. The evidence suggests that BA 10 may play a critical role in the collation, integration and high-level processing of nociception and pain, but also reveals possible functional distinctions between the subregions of BA 10 in this process.

Decreased prefrontal brain activation during verbal fluency task in patients with somatoform pain disorder: An exploratory multi-channel near-infrared spectroscopy study

BACKGROUND

Pain is a common phenomenon. Patients with somatoform pain disorder (SPD) suffer from lasting chronic pain which may cause cognitive impairment. The dysfunction of prefrontal cortex (PFC) may be involved in pain-induced cognition impairment, which is the most important part in regulating of cognitive function. Multi-channel near-infrared spectroscopy (NIRS) is a noninvasive and low-cost functional neuroimaging technique being used to detect the prefrontal cortex activation during cognitive tasks to demonstrate the relationship between PFC dysfunction and cognition impairment in SPD patients.

METHODS

24 patients with SPD and 24 age-, gender- and education level-matched healthy controls were examined by NIRS of the relative concentration of oxygenated hemoglobin (oxy-Hb) in PFC during verbal fluency task (VFT). All data analysis procedures were accomplished under MATLAB, SPM and SPM-fNIRS which is an SPM12-based software for fNIRS analysis.

RESULTS

1. The number of words generated during the VFT tasks in SPD patients were fewer than healthy controls. 2. The activated areas in SPD patients were smaller than healthy controls. 3. The average activation strength of [oxy-Hb] in SPD patients was much lower than healthy controls. 4. The difference of activation areas between left and right lobe were particularly obvious in SPD patients.

CONCLUSION

There are evidences suggested that the markedly dysfunction in PFC especially bilateral dorsolateral prefrontal cortex (DLPFC) areas may be involved in the cognitive deficiency in patients with SPD.

Altered resting-state intra- and inter- network functional connectivity in patients with persistent somatoform pain disorder

Patients with persistent somatoform pain disorder (PSPD) usually experience various functional impairments in pain, emotion, and cognition, which cannot be fully explained by a physiological process or a physical disorder. However, it is still not clear for the mechanism underlying the pathogenesis of PSPD. The present study aimed to explore the intra- and inter-network functional connectivity (FC) differences between PSPD patients and healthy controls (HCs). Functional magnetic resonance imaging (fMRI) was performed in 13 PSPD patients and 23 age- and gender-matched HCs. We used independent component analysis on resting-state fMRI data to calculate intra- and inter-network FCs, and we used the two-sample t-test to detect the FC differences between groups. Spearman correlation analysis was employed to evaluate the correlations between FCs and clinical assessments. As compared to HCs, PSPD patients showed decreased coactivations in the right superior temporal gyrus within the anterior default-mode network and the anterior cingulate cortex within the salience network, and increased coactivations in the bilateral supplementary motor areas within the sensorimotor network and both the left posterior cingulate cortex and the medial prefrontal cortex within the anterior default-mode network. In addition, we found that the PSPD patients showed decreased FNCs between sensorimotor network and audio network as well as visual network, between default-mode network and executive control network as well as audio network and between salience network and executive control network as well as right frontoparietal network, and increased FNCs between sensorimotor network and left frontoparietal network, salience network as well as cerebellum network, which were negatively correlated with the clinical assessments in PSPD patients. Our findings suggest that PSPD patients experience large-scale reorganization at the level of the functional networks, which suggests a possible mechanism underlying the pathogenesis of PSPD.

Loss of M1 Receptor Dependent Cholinergic Excitation Contributes to mPFC Deactivation in Neuropathic Pain

In chronic pain, the medial prefrontal cortex (mPFC) is deactivated and mPFC-dependent tasks such as attention and working memory are impaired. We investigated the mechanisms of mPFC deactivation in the rat spared nerve injury (SNI) model of neuropathic pain. Patch-clamp recordings in acute slices showed that, 1 week after the nerve injury, cholinergic modulation of layer 5 (L5) pyramidal neurons was severely impaired. In cells from sham-operated animals, focal application of acetylcholine induced a left shift of the input/output curve and persistent firing. Both of these effects were almost completely abolished in cells from SNI-operated rats. The cause of this impairment was an ∼60% reduction of an M1-coupled, pirenzepine-sensitive depolarizing current, which appeared to be, at least in part, the consequence of M1 receptor internalization. Although no changes were detected in total M1 protein or transcript, both the fraction of the M1 receptor in the synaptic plasma membrane and the biotinylated M1 protein associated with the total plasma membrane were decreased in L5 mPFC of SNI rats. The loss of excitatory cholinergic modulation may play a critical role in mPFC deactivation in neuropathic pain and underlie the mPFC-specific cognitive deficits that are comorbid with neuropathic pain.SIGNIFICANCE STATEMENT The medial prefrontal cortex (mPFC) undergoes major reorganization in chronic pain. Deactivation of mPFC output is causally correlated with both the cognitive and the sensory component of neuropathic pain. Here, we show that cholinergic excitation of commissural layer 5 mPFC pyramidal neurons is abolished in neuropathic pain rats due to a severe reduction of a muscarinic depolarizing current and M1 receptor internalization. Therefore, in neuropathic pain rats, the acetylcholine (ACh)-dependent increase in neuronal excitability is reduced dramatically and the ACh-induced persisting firing, which is critical for working memory, is abolished. We propose that the blunted cholinergic excitability contributes to the functional mPFC deactivation that is causal for the pain phenotype and represents a cellular mechanism for the attention and memory impairments comorbid with chronic pain.

Altered Neural Correlates of Emotion Associated Pain Processing in Persistent Somatoform Pain Disorder: An fMRI Study

Patients with persistent somatoform pain disorder (PSPD) suffer from long-term pain and emotional conflicts. Recently, accumulating evidence indicated that emotion has a significant role in pain perception of somatoform pain disorder. To further understand the association between emotion and pain-related brain activities, functional activities of patients with PSPD fulfilling ICD-10 criteria and healthy controls were assessed using functional magnetic resonance imaging technology, while participants viewed a series of positive, neutral, or negative pictures with or without pinprick pain stimulation. Results showed that patients with PSPD had altered brain activities in the parietal gyrus, temporal gyrus, posterior cingulate cortex, prefrontal cortex, and parahippocampus in response to pinprick pain stimuli during different emotions compared with the healthy control group. Moreover, patients with PSPD consistently showed hyperactivities in the prefrontal, the fusiform gyrus and the insula in response to negative stimuli under pinprick pain vs. non-pain condition. The current findings provide some insights into the underlying relationship between emotion and pain-related brain activity in patients with PSPD, which is of both theoretical and clinical importance.

Reduced local field potential power in the medial prefrontal cortex by noxious stimuli

Nociceptive signals produced by noxious stimuli at the periphery reach the brain through ascending pathways. These signals are processed by various brain areas and lead to activity changes in those areas. The medial prefrontal cortex (mPFC) is involved in higher cognitive functions and emotional processing. It receives projections from brain areas involved in nociception. In this study, we investigated how nociceptive input from the periphery changes the local field potential (LFP) activity in the mPFC. Three different types of noxious stimuli were applied to the hind paw contralateral to the LFP recording site. They were transcutaneous electrical stimulations, mechanical stimuli and a chemical stimulus (formalin injection). High intensity transcutaneous stimulations (10V to 50V) and noxious mechanical stimulus (pinch) significantly reduced the LFP power during the stimulating period (p<0.05), but not the low intensity subcutaneous stimulations (0.1V to 5V) and other innocuous mechanical stimuli (brush and pressure). More frequency bands were inhibited with increased intensity of transcutaneous electrical stimulation, and almost all frequency bands were inhibited by stimulations at or higher than 30v. Pinch significantly reduced the power for beta band and formalin injection significantly reduced the power of alpha and beta band. Our data demonstrated the noxious stimuli-induced reduction of LFP power in the mPFC, which indicates the active processing of nociceptive information by the mPFC.

Altered fMRI resting-state connectivity in individuals with fibromyalgia on acute pain stimulation

BACKGROUND

Fibromyalgia is a chronic widespread pain condition, with patients commonly reporting other symptoms such as sleep difficulties, memory complaints and fatigue. The use of magnetic resonance imaging (MRI) in fibromyalgia has allowed for the detection of neural abnormalities, with alterations in brain activation elicited by experimental pain and alterations in resting state connectivity related to clinical pain.

METHODS

In this study, we sought to monitor state changes in resting brain connectivity following experimental pressure pain in fibromyalgia patients and healthy controls. Twelve fibromyalgia patients and 15 healthy controls were studied by applying discrete pressure stimuli to the thumbnail bed during MRI. Resting-state functional MRI scanning was performed before and immediately following experimental pressure pain. We investigated changes in functional connectivity to the thalamus and the insular cortex.

RESULTS

Acute pressure pain increased insula connectivity to the anterior cingulate and the hippocampus. Additionally, we observed increased thalamic connectivity to the precuneus/posterior cingulate cortex, a known part of the default mode network, in patients but not in controls. This connectivity was correlated with changes in clinical pain.

CONCLUSIONS

These data reporting changes in resting-state brain activity following a noxious stimulus suggest that the acute painful stimuli may contribute to the alteration of the neural signature of chronic pain. WHAT DOES THIS STUDY/ADD?: In this study acute pain application shows an echo in functional connectivity and clinical pain changes in chronic pain.

Neural correlates of somatoform disorders from a meta-analytic perspective on neuroimaging studies

Somatoform disorders (SD) are common medical disorders with prevalence rates between 3.5% and 18.4%, depending on country and medical setting. SD as outlined in the ICD-10 exhibits various biological, social, and psychological pathogenic factors. Little is known about the neural correlates of SD. The aims of this meta-analysis are to identify neuronal areas that are involved in SD and consistently differ between patients and healthy controls. We conducted a systematic literature research on neuroimaging studies of SD. Ten out of 686 studies fulfilled the inclusion criteria and were analyzed using activation likelihood estimation. Five neuronal areas differ between patients with SD and healthy controls namely the premotor and supplementary motor cortexes, the middle frontal gyrus, the anterior cingulate cortex, the insula, and the posterior cingulate cortex. These areas seem to have a particular importance for the occurrence of SD. Out of the ten studies two did not contribute to any of the clusters. Our results seem to largely overlap with the circuit network model of somatosensory amplification for SD. It is conceivable that functional disorders, independent of the clinical impression, show similar neurobiological processes. While overlaps do occur it is necessary to understand single functional somatic syndromes and their aetiology for future research, terminology, and treatment guidelines.

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Five neurobiological areas correlate with the occurrence of somatoform disorders (SD).

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Areas are crucial for emotional, evaluative and cognitive aspects of pain processing.

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Prefrontal areas indicate involvement of pain memory in SD.

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Functional disorders might have central sensitization as an underlying factor.

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Results do not support the classification of SD as medically unexplained symptoms.

Alexithymic Trait, Painful Heat Stimulation, and Everyday Pain Experience

BACKGROUND

Alexithymia was found to be associated with a variety of somatic complaints, including somatoform pain symptoms. This study addressed the question of whether the different facets of alexithymia are related to responses in heat pain stimulation and its interrelations with levels of everyday pain as assessed by self-report.

METHODS

In the study, sensitivity to heat pain was assessed in 50 healthy female participants. Alexithymia facets were assessed by the Toronto Alexithymia Scale. Pain threshold and tolerance were determined using a testing the limits procedure. Participants, furthermore, rated subjective intensities and unpleasantness of tonic heat stimuli (45.5-47.5°C) on visual analog scales and on a questionnaire. Possible confounding with temperature sensitivity and mood was controlled. Everyday pain was assessed by self-report addressing everyday pain frequency, intensity, and impairment experienced over the last 2 months.

RESULTS

Main results were that the facets of alexithymia were differentially associated with pain perception. The affective scale "difficulties in describing feelings" was associated with hyposensitivity to pain as indicated by higher pain tolerance scores. Furthermore, everyday pain frequency was related to increased alexithymia values on the affective scale "difficulties in identifying feelings," whereas higher values on the cognitive alexithymia scale "externally oriented thinking" were related to lower pain impairment and intensity.

CONCLUSION

We conclude that the different facets of alexithymia are related to alternations in pain processing. Further research on clinical samples is necessary to elucidate whether different aspects of alexithymia act as a vulnerability factor for the development of pain symptoms.

Increased cerebral cannabinoid-1 receptor availability is a stable feature of functional dyspepsia: a [F]MK-9470 PET study

BACKGROUND

Functional dyspepsia (FD) is a prevalent functional gastrointestinal disorder (FGID) defined by chronic epigastric symptoms in the absence of organic abnormalities likely to explain them. Comorbidity with mood and anxiety disorders as well as with other FGIDs and functional somatic syndrome (FSS) is high. FD is characterized by abnormal regional cerebral activity in cognitive/affective pain modulatory circuits, but it is unknown which neurotransmitter systems are involved. The authors aimed to assess and compare in vivo cerebral cannabinoid-1 (CB1) receptor availability between FD patients and age-, gender- and BMI-matched healthy controls (HC).

METHODS

Twelve FD patients and 12 matched HC were investigated using positron emission tomography (PET) with the CB1 receptor radioligand [(18)F]MK-9470. Nine of the patients received a second PET scan after a naturalistic follow-up period of 36 ± 9.6 months (range: 25.2-50.4 months).

RESULTS

FD patients had significantly higher CB1 receptor availability in the cerebral regions involved in (visceral) nociception (brainstem, insula, anterior cingulate cortex) as well as in the homeostatic and hedonic regulation of food intake [hypothalamus, (ventral) striatum] (p < 0.05 corrected for multiple testing, region of interest analysis), which persisted after a follow-up period of 36 ± 9.6 months.

CONCLUSIONS

Although these findings need replication in larger samples, they suggest that the abnormal brain activity in several of these regions, previously demonstrated in FD, may be due to a sustained endocannabinoid system dysfunction, identifying it as a potential novel target for treatment and warranting further studies to elucidate whether it is also a feature of other FGIDs or FSSs.

Interoception and stress

Afferent neural signals are continuously transmitted from visceral organs to the brain. Interoception refers to the processing of visceral-afferent neural signals by the central nervous system, which can finally result in the conscious perception of bodily processes. Interoception can, therefore, be described as a prominent example of information processing on the ascending branch of the brain–body axis. Stress responses involve a complex neuro-behavioral cascade, which is elicited when the organism is confronted with a potentially harmful stimulus. As this stress cascade comprises a range of neural and endocrine pathways, stress can be conceptualized as a communication process on the descending branch of the brain–body axis. Interoception and stress are, therefore, associated via the bi-directional transmission of information on the brain–body axis. It could be argued that excessive and/or enduring activation (e.g., by acute or chronic stress) of neural circuits, which are responsible for successful communication on the brain–body axis, induces malfunction and dysregulation of these information processes. As a consequence, interoceptive signal processing may be altered, resulting in physical symptoms contributing to the development and/or maintenance of body-related mental disorders, which are associated with stress. In the current paper, we summarize findings on psychobiological processes underlying acute and chronic stress and their interaction with interoception. While focusing on the role of the physiological stress axes (hypothalamic-pituitary-adrenocortical axis and autonomic nervous system), psychological factors in acute and chronic stress are also discussed. We propose a positive feedback model involving stress (in particular early life or chronic stress, as well as major adverse events), the dysregulation of physiological stress axes, altered perception of bodily sensations, and the generation of physical symptoms, which may in turn facilitate stress.

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.

Dissociation of regional activity in default mode network in medication-naive, first-episode somatization disorder

Background

Patients with somatization disorder (SD) have altered neural activity in the brain regions of the default mode network (DMN). However, the regional alteration of the DMN in SD remains unknown. The present study was designed to investigate the regional alterations of the DMN in patients with SD at rest.

Methods

Twenty-five first-episode, medication-naive patients with SD and 28 age-, sex-, education- matched healthy controls underwent a resting-state functional magnetic resonance imaging (fMRI) scan. The fractional amplitude of low-frequency fluctuations (fALFF) was applied to analyze the data.

Results

Patients with SD showed a dissociation pattern of resting-state fALFF in the DMN, with increased fALFF in the bilateral superior medial prefrontal cortex (MPFC, BA8, 9) and decreased fALFF in the left precuneus (PCu, BA7). Furthermore, significantly positive correlation was observed between the z values of the voxels within the bilateral superior MPFC and somatization subscale scores of the Symptom Check List (SCL-90) in patients with SD.

Conclusions

Our findings indicate that there is a dissociation pattern of the anterior and posterior DMN in first-episode, treatment-naive patients with SD. The results provide new insight for the importance of the DMN in the pathophysiology of SD.

Illness behavior in patients with chronic low back pain and activation of the affective circuitry of the brain

OBJECTIVE

Patients with chronic low back pain (cLBP) show a range of behavioral patterns that do not correlate with degree of spinal abnormality found in clinical, radiological, neurophysiological, or laboratory investigations. This may indicate an augmented central pain response, consistent with factors that mediate and maintain psychological distress in this group.

METHODS

Twenty-four cLBP patients were scanned with functional magnetic resonance imaging while receiving noxious thermal stimulation to the right hand. Patients were clinically assessed into those with significant pain-related illness behavior (Waddell signs [WS]-H) or without (WS-L) based on WS.

RESULTS

Our findings revealed a significant increase in brain activity in WS-H versus WS-L patients in response to noxious heat in the right amygdala/parahippocampal gyrus and ventrolateral prefrontal and insular cortex (at a VoxelPThreshold = 0.01). We found no difference between groups for heat pain thresholds (t(22) = -1.17, p = .28) or sensory-discriminative pain regions.

CONCLUSIONS

Patients with cLBP displaying major pain behavior have increased activity in the emotional circuitry of the brain. This study is the first to suggest an association between a specific clinical test in cLBP and neurobiology of the brain. Functional magnetic resonance imaging may provide a tool capable of enhancing diagnostic accuracy and affecting treatment decisions in cases where no structural cause can be identified.

Hypersensitivity and hyperalgesia in somatoform pain disorders

OBJECTIVE

In psychiatry, pain disorders not explained by structural lesions have been classified for decades as somatoform pain disorders, the underlying concept being somatization. In a parallel move, somatic medicine has defined an expanding group of similar pain disorders, known as functional pain syndromes. Functional pain syndromes are characterized by enhanced pain sensitivity. The aim of our study was to investigate the proportion of patients with somatoform pain disorders who also meet the criteria of functional pain syndromes and the extent to which patients with somatoform pain disorders also show enhanced pain sensitivity.

METHODS

Data on pain sensitivity in 120 hospitalized patients were obtained by means of two algometric methods. The group of patients with somatoform pain disorders was further divided into two subsets: patients with and those without a co-diagnosis of a functional pain syndrome. Patients with nociceptive pain served as control group.

RESULTS

Of the 120 in-patients selected, 67 fulfilled the criteria of a somatoform pain disorder of which 41 (61%) also met the co-diagnosis of a functional pain syndrome. Patients with somatoform pain disorder differed from controls in that they showed enhanced pain sensitivity, irrespective of whether a functional pain syndrome was concomitantly present (P<.001).

CONCLUSIONS

Somatoform pain disorders show considerable overlap with functional pain syndromes, including enhanced pain sensitivity. This suggests the relevance of integrating somatosensory aspects of pain into a modified understanding of somatoform pain disorders.

Regional gray matter volume and anxiety-related traits interact to predict somatic complaints in a non-clinical sample

Somatic complaints can be important features of an individual's expression of anxiety. Anxiety-related traits are also risk factors for somatic symptoms. However, it is not known which neuroanatomical mechanisms may be responsible for this relationship. In this study, our first step was to use voxel-based morphometry (VBM) approaches to investigate the neuroanatomical basis underlying somatic complaints in a large sample of healthy subjects. We found a significant positive correlation between somatic complaints and parahippocampal gyrus (PHG) volume adjacent to the entorhinal cortex. Further analysis revealed that the interaction between PHG volume/entorhinal cortex and neuroticism-anxiety (N-Anx) predicted somatic complaints. Specifically, somatic complaints were associated with higher N-Anx for individuals with increased PHG volume. These findings suggest that increased PHG volume and higher trait anxiety can predict vulnerability to somatic complaints in the general population.

Struggling in an emotional avoidance culture: a qualitative study of stress as a predisposing factor for somatoform disorders

OBJECTIVE

To explore patterns of experienced stress and stress reactions before the onset of illness in the life history of patients with severe somatoform disorders to identify predisposing stress-mechanisms.

METHODS

A systematic, thematic analysis was conducted on data collected from 24 semi-structured individual life history interviews.

RESULTS

Generally, patients had experienced high psychosocial stress during childhood/youth. However, there was considerable variability. Characteristic of all patients were narrations of how communication with significant adults about problems, concerns, and emotions related to stress were experienced to be difficult. The patients described how this involved conflicts stemming from perceived absent, insufficient, or dismissive communication during interactions with significant adults. We conceptualized this empirically based core theme as "emotional avoidance culture." Further, three related subthemes were identified: Generally, patients 1.) experienced difficulties communicating problems, concerns, and related complex feelings in close social relations; 2.) adapted their emotional reactions and communication to an emotional avoidance culture, suppressing their needs, vulnerability and feelings of sadness and anger that were not recognized by significant adults; and 3.) disconnected their stress reaction awareness from stressful bodily sensations by using avoidant behaviors e.g. by being highly active.

CONCLUSION

Patients adapted to an emotional avoidance culture characterized by difficult and conflicting communication of concerns and related emotions in social interactions with significant adults. Patients experienced low ability to identify and express stress-related cognitions, emotions and feelings, and low bodily and emotional self-contact, which made them vulnerable to stressors. Generally, patients resolved stress by avoidant behaviors, prolonging their stress experience.

Pleasant touch moderates the subjective but not objective aspects of body perception

Un-myelinated C tactile afferents (CT afferents) are a key finding in affective touch. These fibers, which activate in response to a caress-like touch to hairy skin (CT afferents are not found in palm skin), may have more in common with interoceptive systems encoding body ownership, than afferent systems processing other tactile stimuli. We tested whether subjective embodiment of a rubber hand (measured through questionnaire items) was increased when tactile stimulation was applied to the back of the hand at a rate optimal for CT afferents (3 cm/s) vs. stimulation of glabrous skin (on the palm of the hand) or at a non-optimal rate (30 cm/s), which should not activate these fibers. We also collected ratings of tactile pleasantness and a measure of perceived limb position, proprioceptive drift, which is mediated by different mechanisms of multisensory integration than those responsible for feelings of ownership. The results of a multiple regression analysis revealed that proprioceptive drift was a significant predictor of subjective strength of the illusion when tactile stimuli were applied to the back of the hand, regardless of stroking speed. This relationship was modified by pleasantness, with higher ratings when stimulation was applied to the back of the hand at the slower vs. faster stroking speed. Pleasantness was also a unique predictor of illusion strength when fast stroking was applied to the palm of the hand. However, there were no conditions under which pleasantness was a significant predictor of drift. Since the illusion was demonstrated at a non-optimal stroking speed an integrative role for CT afferents within the illusion cannot be fully supported. Pleasant touch, however, does moderate the subjective aspects of the rubber hand illusion, which under certain tactile conditions may interact with proprioceptive information about the body or have a unique influence on subjective body perception.

Imaging pain: a potent means for investigating pain mechanisms in patients

Chronic pain is a state of physical suffering strongly associated with feelings of anxiety, depression and despair. Disease pathophysiology, psychological state, and social milieu can influence chronic pain, but can be difficult to diagnose based solely on clinical presentation. Here, we review brain neuroimaging research that is shaping our understanding of pain mechanisms, and consider how such knowledge might lead to useful diagnostic tools for the management of persistent pain in individual patients.

Distinctive neural responses to pain stimuli during induced sadness in patients with somatoform pain disorder: An fMRI study

Pain is a multidimensional phenomenon. Patients with somatoform pain disorder suffer from long-lasting pain, with the pathology being closely associated with cognitive–emotional components. Differences between these patients and controls in cerebral responses to pain stimuli have been reported. However, to our knowledge, no studies of somatoform pain disorder have evaluated altered pain-related brain activation as modulated by emotional dysregulation. We examined the distinct neural mechanism that is engaged in response to two different pain intensities in a sad emotional condition, performing functional magnetic resonance imaging (fMRI) on a group of 11 somatoform pain patients and an age-matched control group. Our results showed that the ratio for low-pain intensity ratings between the sad and neutral conditions in patients was higher than in controls. They also showed significant increased activation in the anterior/posterior insula in the low pain sadness condition. Furthermore, there was specific functional connectivity between the anterior insula and the parahippocampus in patients during presentation of low-pain stimuli in the sad context. These findings suggest that a negative emotional context such as sadness contributes to dysfunctional pain processing in somatoform pain disorder. Greater sensitivity to low levels of pain in an emotional context of sadness might be an important aspect of the psychopathology of somatoform pain disorder.

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Patients show higher pain sensitivities for low pain under sadness.

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The insula to low-pain stimuli are particularly changeable in patients.

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There was strong connectivity between the insula and the parahippocampus in patients.

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We suggest potential importance of emotional context in somatoform pain disorder.

Structural basis of empathy and the domain general region in the anterior insular cortex

Empathy is key for healthy social functioning and individual differences in empathy have strong implications for manifold domains of social behavior. Empathy comprises of emotional and cognitive components and may also be closely linked to sensorimotor processes, which go along with the motivation and behavior to respond compassionately to another person's feelings. There is growing evidence for local plastic change in the structure of the healthy adult human brain in response to environmental demands or intrinsic factors. Here we have investigated changes in brain structure resulting from or predisposing to empathy. Structural MRI data of 101 healthy adult females was analyzed. Empathy in fictitious as well as real-life situations was assessed using a validated self-evaluation measure. Furthermore, empathy-related structural effects were also put into the context of a functional map of the anterior insular cortex (AIC) determined by activation likelihood estimate (ALE) meta-analysis of previous functional imaging studies. We found that gray matter (GM) density in the left dorsal AIC correlates with empathy and that this area overlaps with the domain general region (DGR) of the anterior insula that is situated in-between functional systems involved in emotion-cognition, pain, and motor tasks as determined by our meta-analysis. Thus, we propose that this insular region where we find structural differences depending on individual empathy may play a crucial role in modulating the efficiency of neural integration underlying emotional, cognitive, and sensorimotor information which is essential for global empathy.

Frequency shifts in the anterior default mode network and the salience network in chronic pain disorder

BACKGROUND

Recent functional imaging studies on chronic pain of various organic etiologies have shown significant alterations in both the spatial and the temporal dimensions of the functional connectivity of the human brain in its resting state. However, it remains unclear whether similar changes in intrinsic connectivity networks (ICNs) also occur in patients with chronic pain disorder, defined as persistent, medically unexplained pain.

METHODS

We compared 21 patients who suffered from chronic pain disorder with 19 age- and gender-matched controls using 3T-fMRI. All neuroimaging data were analyzed using both independent component analysis (ICA) and power spectra analysis.

RESULTS

In patients suffering from chronic pain disorder, the fronto-insular 'salience' network (FIN) and the anterior default mode network (aDMN) predominantly oscillated at higher frequencies (0.20 - 0.24 Hz), whereas no significant differences were observed in the posterior DMN (pDMN) and the sensorimotor network (SMN).

CONCLUSIONS

Our results indicate that chronic pain disorder may be a self-sustaining and endogenous mental process that affects temporal organization in terms of a frequency shift in the rhythmical dynamics of cortical networks associated with emotional homeostasis and introspection.

The influence of physical activity on pain thresholds in patients with depression and multiple somatoform symptoms

OBJECTIVES

Pain is a common symptom with high occurrence in somatoform syndromes and depressive disorders. Research in this area often focuses on experimental induction of pain and subsequent assessment of pain thresholds, ensuring repeatable stimuli of defined quality. Results on sensitivity to experimental pain in major depression are inconclusive, and data on pain thresholds in multiple somatoform symptoms are scarce. The goals of the present study were to differentiate between groups regarding the pressure pain thresholds, and to investigate the possible influence of physical activity on the pain thresholds in these groups. We postulate that physical fitness and physical activity influence pain thresholds in depression and persons with multiple somatoform symptoms.

METHODS

Thirty-eight persons with major depression, 26 persons with a minimum of 6 to 8 somatoform symptoms (somatoform symptom index 8, SSI-8), and 47 healthy participants participated in the study. Baseline values of pressure pain thresholds assessed at different sites of the body were compared with those after 1 week of increased and 1 week of reduced physical activity.

RESULTS

We used repeated measurement design (MANCOVA) and partial correlations for data analysis. Depressed participants reported lower pain thresholds compared with controls, and persons with SSI-8 showed intermediate thresholds. After 1 week of physical activity, participants reported higher pain thresholds. Men had higher pain thresholds following activity as compared with women. Participants who reported higher general fitness also showed higher pain thresholds. Sensitivity to pressure pain is associated with depression, but not with multiple somatoform symptoms.

DISCUSSION

Short low-graded exercise can have reducing effects on perception of pressure pain. Physical activity level is a relevant covariate when using pressure pain assessment. Reduced general fitness can partially account for lower pain thresholds in depression.