The PerPAIN trial: a pilot randomized controlled trial of personalized treatment allocation for chronic musculoskeletal pain-a protocol

BACKGROUND

The therapy of chronic musculoskeletal pain (CMSP) is complex and the treatment results are often insufficient despite numerous therapeutic options. While individual patients respond very well to specific interventions, other patients show no improvement. Personalized treatment assignment offers a promising approach to improve response rates; however, there are no validated cross-disease allocation algorithms available for the treatment of chronic pain in validated personalized pain interventions. This trial aims to test the feasibility and safety of a personalized pain psychotherapy allocation with three different treatment modules and estimate initial signals of efficacy and utility of such an approach compared to non-personalized allocation.

METHODS

This is a randomized, controlled assessor-blinded pilot trial with a multifactorial parallel arm design. CMSP patients (n = 105) will be randomly assigned 1:1 to personalized or non-personalized treatment based on a cluster assignment of the West Haven-Yale Multidimensional Pain Inventory (MPI). In the personalized assignment condition, patients with high levels of distress receive an emotional distress-tailored intervention, patients with pain-related interference receive an exposure/extinction-tailored treatment intervention and patients who adapt relatively well to the pain receive a low-level smartphone-based activity diary intervention. In the control arm, patients receive one of the two non-matching interventions. Effect sizes will be calculated for change in core pain outcome domains (pain intensity, physical and emotional functioning, stress experience, participant ratings of improvement and satisfaction) after intervention and at follow-up. Feasibility and safety outcomes will assess rates of recruitment, retention, adherence and adverse events. Additional data on neurobiological and psychological characteristics of the patients are collected to improve treatment allocation in future studies.

CONCLUSION

Although the call for personalized treatment approaches is widely discussed, randomized controlled trials are lacking. As the personalization of treatment approaches is challenging, both allocation and intervention need to be dynamically coordinated. This study will test the feasibility and safety of a novel study design in order to provide a methodological framework for future multicentre RCTs for personalized pain psychotherapy.

TRIAL REGISTRATION

German Clinical Trials Register, DRKS00022792 ( https://www.drks.de ). Prospectively registered on 04/06/2021.

Hyper-Activation of Endogenous GLP-1 System to Gram-negative Sepsis Is Associated With Early Innate Immune Response and Modulated by Diabetes

BACKGROUND

Culture-positive gram-negative sepsis induces greater magnitude of early innate immunity /inflammatory response compared with culture-negative sepsis. We previously demonstrated increased activation of anti-inflammatory Glucagon Like Peptide-1 (GLP-1) hormone in initial phase of sepsis more pronounced in diabetes patients. However, whether GLP-1 system is hyperactivated during the early innate immune response to gram-negative sepsis and modulated by diabetes remains unknown.

OBJECTIVES

Total and active GLP-1, soluble Dipeptidyl peptidase 4 (sDPP-4) enzyme, and innate immunity markers presepsin (sCD14) and procalcitonin (PCT) in plasma were determined by ELISA on admission and after 2 to 4 days in 37 adult patients with and without type 2 diabetes and gram-negative or culture-negative sepsis of different severity.

RESULTS

Severe but not non-severe sepsis was associated with markedly increased GLP-1 system response, which correlated with PCT and the organ dysfunction marker lactate. Culture-positive gram-negative bacteria but not culture-negative sepsis induced hyper-activation of GLP-1 system, which correlated with increased innate immune markers sCD14, PCT, and lactate. GLP-1 inhibitory enzyme sDPP-4 was down regulated by sepsis and correlated negatively with sCD14 in gram-negative sepsis. Diabetic patients demonstrated increased GLP-1 response but significantly weaker innate immune response to severe and gram-negative sepsis.

CONCLUSIONS

Early stage of gram-negative sepsis is characterized by endogenous GLP-1 system hyperactivity associated with over activation of innate immune response and organ dysfunction, which are modulated by diabetes. Total GLP-1 may be novel marker for rapid diagnosis of gram-negative sepsis and its severity.

The evaluation and brain representation of pleasant touch in chronic and subacute back pain

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Chronic back pain (CBP) showed less positive evaluations of touch.

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Highest response to pleasant touch in SI and SII and insula in chronic back pain.

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Highest response to pleasant touch in ventral striatum in subacute back pain (SABP).

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Correlations of brain responses with pain interference in CBP and distress in SABP.

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Brain-behavior changes in pleasant touch processing may be a marker of pain chronicity.

If touch is perceived as pleasant, it can counteract the experience of pain. However, its pain-inhibitory function might be disturbed in chronic pain and this could contribute to pain-related interference. We investigated the perception of pleasant touch and its brain correlates in chronic back pain patients (CBP) compared to subacute back pain patients (SABP) and healthy controls (HC) using soft brush strokes. CBP showed less positive evaluations of touch. We found the highest activation in somatosensory and insular cortices in CBP, ventral striatum (VS) in SABP, and the orbitofrontal cortex in HC. Brain responses were significantly positively correlated with pleasantness ratings in HC and SABP, but not CBP. Further, the insula responses in CBP were positively correlated with pain-related interference and the VS activation in SABP correlated negatively with affective distress. Brain and behavioral changes in the processing of touch and its pleasantness may be a marker of pain chronicity and raise questions about the therapeutic value of pleasant touch in pain prevention and treatment.

Relieving phantom limb pain with multimodal sensory-motor training

OBJECTIVE

The causes for the disabling condition of phantom limb pain (PLP), affecting 85% of amputees, are so far unknown, with few effective treatments available. Sensory feedback based strategies to normalize the motor commands to control the phantom limb offer important targets for new effective treatments as the correlation between phantom limb motor control and sensory feedback from the motor intention has been identified as a possible mechanism for PLP development.

APPROACH

Ten upper-limb amputees, suffering from chronic PLP, underwent 16 days of intensive training on phantom-limb movement control. Visual and tactile feedback, driven by muscular activity at the stump, was provided with the aim of reducing PLP intensity.

MAIN RESULTS

A 32.1% reduction of PLP intensity was obtained at the follow-up (6 weeks after the end of the training, with an initial 21.6% reduction immediately at the end of the training) reaching clinical effectiveness for chronic pain reduction. Multimodal sensory-motor training on phantom-limb movements with visual and tactile feedback is a new method for PLP reduction.

SIGNIFICANCE

The study results revealed a substantial reduction in phantom limb pain intensity, obtained with a new training protocol focused on improving phantom limb motor output using visual and tactile feedback from the stump muscular activity executed to move the phantom limb.

Sepsis-induced activation of endogenous GLP-1 system is enhanced in type 2 diabetes

BACKGROUND

High levels of circulating GLP-1 are associated with severity of sepsis in critically ill nondiabetic patients. Whether patients with type 2 diabetes (T2D) display different activation of the endogenous GLP-1 system during sepsis and whether it is affected by diabetes-related metabolic parameters are not known.

METHODS

Serum levels of GLP-1 (total and active forms) and its inhibitor enzyme sDPP-4 were determined by ELISA on admission and after 2 to 4 days in 37 sepsis patients with (n = 13) and without T2D (n = 24) and compared to normal healthy controls (n = 25). Correlations between GLP-1 system activation and clinical, inflammatory, and diabetes-related metabolic parameters were performed.

RESULTS

A 5-fold (P < .001) and 2-fold (P < .05) increase in active and total GLP-1 levels, respectively, were found on admission as compared to controls. At 2 to 4 days from admission, the level of active GLP-1 forms in surviving patients were decreased significantly (P < .005), and positively correlated with inflammatory marker CRP (r = 0.33, P = .05). T2D survivors displayed a similar but more enhanced pattern of GLP-1 response than nondiabetic survivors. Nonsurvivors demonstrate an early extreme increase of both total and active GLP-1 forms, 9.5-fold and 5-fold, respectively (P < .05). The initial and late levels of circulating GLP-1 inhibitory enzyme sDPP-4 were twice lower in all studied groups (P < .001), compared with healthy controls.

CONCLUSIONS

Taken together, these data indicate that endogenous GLP-1 system is activated during sepsis. Patients with T2D display an enhanced and prolonged activation as compared to nondiabetic patients. Extreme early increased GLP-1 levels during sepsis indicate poor prognosis.

Interaction between striatal volume and DAT1 polymorphism predicts working memory development during adolescence

There is considerable inter-individual variability in the rate at which working memory (WM) develops during childhood and adolescence, but the neural and genetic basis for these differences are poorly understood. Dopamine-related genes, striatal activation and morphology have been associated with increased WM capacity after training. Here we tested the hypothesis that these factors would also explain some of the inter-individual differences in the rate of WM development.

We measured WM performance in 487 healthy subjects twice: at age 14 and 19. At age 14 subjects underwent a structural MRI scan, and genotyping of five single nucleotide polymorphisms (SNPs) in or close to the dopamine genes DRD2, DAT-1 and COMT, which have previously been associated with gains in WM after WM training. We then analyzed which biological factors predicted the rate of increase in WM between ages 14 and 19.

We found a significant interaction between putamen size and DAT1/SLC6A3 rs40184 polymorphism, such that TC heterozygotes with a larger putamen at age 14 showed greater WM improvement at age 19.

The effect of the DAT1 polymorphism on WM development was exerted in interaction with striatal morphology. These results suggest that development of WM partially share neuro-physiological mechanism with training-induced plasticity.

Assessing Suffering in Experimental Pain Models

Abstract. Although suffering is a central issue in pain, there is only little research on this topic. The aim of this study was to assess suffering in an experimental context using various stimulation methods and durations, and to examine which psychological or psychophysiological measures covary with pain-related suffering. Twenty-one healthy volunteers participated in two experiments in which we used tonic thermal and phasic electric stimuli with short and long stimulus durations. The participants rated pain intensity, unpleasantness, and pain-related suffering on separate visual analog scales (VAS) and completed the Pictorial Representation of Illness and Self Measure (PRISM), originally developed to assess suffering in chronic illness. We measured heart rate, skin conductance responses (SCRs), and the electromyogram (EMG) of the musculus corrugator supercilii. For both heat and electric pain, we obtained high ratings on the suffering scale confirming that suffering can be evoked in experimental pain conditions. Whereas pain intensity and unpleasantness were highly correlated, both scales were less highly related to suffering, indicating that suffering is distinct from pain intensity and unpleasantness. Higher suffering ratings were associated with more pronounced fear of pain and increased private self-consciousness. Pain-related suffering was also related to high resting heart rate, increased SCR, and decreased EMG during painful stimulation. These results offer an approach to the assessment of suffering in an experimental setting using thermal and electric pain stimulation and shed light on its psychological and psychophysiological correlates.

[Psychological approaches to pain in Germany. Review and outlook]

Pain perception is a complex experience that entails somatic and psychological factors. This is especially true for chronic pain where increasing chronicity leads to a growing significance of psychological factors such as learning and memory processes or cognitive evaluation at the expense of nociceptive processes. Hardly any other area of health-related research and health care has such an interdisciplinary organization of research, treatment, and education. Psychological pain research and psychological treatment of pain have become specializations in their own right. For the future of this research area, a differential analysis of the contribution of psychological factors to chronicity is important. For a mechanism-oriented treatment, the development of new treatment approaches and the analysis of specific subgroups for a better differential indication of treatments is needed.

Disentangling the autism-anxiety overlap: fMRI of reward processing in a community-based longitudinal study

Up to 40% of youth with autism spectrum disorder (ASD) also suffer from anxiety, and this comorbidity is linked with significant functional impairment. However, the mechanisms of this overlap are poorly understood. We investigated the interplay between ASD traits and anxiety during reward processing, known to be affected in ASD, in a community sample of 1472 adolescents (mean age=14.4 years) who performed a modified monetary incentive delay task as part of the Imagen project. Blood-oxygen-level dependent (BOLD) responses to reward anticipation and feedback were compared using a 2x2 analysis of variance test (ASD traits: low/high; anxiety symptoms: low/high), controlling for plausible covariates. In addition, we used a longitudinal design to assess whether neural responses during reward processing predicted anxiety at 2-year follow-up. High ASD traits were associated with reduced BOLD responses in dorsal prefrontal regions during reward anticipation and negative feedback. Participants with high anxiety symptoms showed increased lateral prefrontal responses during anticipation, but decreased responses following feedback. Interaction effects revealed that youth with combined ASD traits and anxiety, relative to other youth, showed high right insula activation when anticipating reward, and low right-sided caudate, putamen, medial and lateral prefrontal activations during negative feedback (all clusters PFWE<0.05). BOLD activation patterns in the right dorsal cingulate and right medial frontal gyrus predicted new-onset anxiety in participants with high but not low ASD traits. Our results reveal both quantitatively enhanced and qualitatively distinct neural correlates underlying the comorbidity between ASD traits and anxiety. Specific neural responses during reward processing may represent a risk factor for developing anxiety in ASD youth.

Treatment history and placebo responses to experimental and clinical pain in chronic pain patients

BACKGROUND

Placebo analgesia refers to the reduction in pain due to the administration of an inert treatment. It is induced by expectations of pain relief which are enhanced by learning mechanisms. In healthy humans, prior positive experiences enhance the placebo response. However, the effects of patients' prior experiences with treatment on placebo responses have not yet been examined. This study investigated how verbal information, learning and treatment history influence the magnitude of placebo analgesia in chronic pain.

METHODS

We administered a pharmacological placebo intervention in a sample of chronic pain patients (n = 49) who were seeking treatment in an outpatient pain clinic. Analyses were based on placebo responders.

RESULTS

We found that verbal information about a potent pain-relieving effect of the intervention induced a large placebo analgesic response to both acute experimental (F(1,44) = 43.35, p < 0.001) and chronic pain (F(1,44) = 37.72, p < 0.001). However, the placebo responses to experimental and chronic pain were not significantly related (r = 0.012, p = 0.95). An additional conditioning procedure did not significantly enhance placebo analgesia. Treatment history modulated the magnitude of the placebo response: patients with a more negative pain-related treatment history reported significantly larger placebo responses to their own chronic pain (τ = 0.271, p = 0.044).

CONCLUSIONS

We could show that placebo responses to both acute and chronic pain are high in pain treatment settings and that treatment history modulates this effect. Different mechanisms might underlie placebo responses to acute and chronic pain. Our findings highlight the necessity of considering placebo responses and treatment history in the treatment of chronic pain. WHAT DOES THIS STUDY ADD?: Placebo analgesia following verbal information of potent pain relief is high in chronic pain patients in a clinical setting. It is modulated by treatment history. Different mechanisms might underlie placebo analgesia to acute and chronic pain.

Neural reward processing in individuals remitted from major depression

BACKGROUND

Dysfunctional behavioural and neural processing of reward has been found in currently depressed individuals. However, little is known about altered reward processing in remitted depressed individuals.

METHOD

A total of 23 medication-free individuals with remitted major depressive disorder (rMDD) and 23 matched healthy controls (HCs) performed a reward task during functional magnetic resonance imaging. We also investigated reward dependence, novelty seeking and harm avoidance using the Tridimensional Personality Questionnaire and their association with neural responses of reward processing.

RESULTS

Compared to HCs, individuals with rMDD exhibited enhanced responses to reward-predicting cues in the hippocampus, amygdala and superior frontal gyrus. When reward was delivered, rMDD subjects did not significantly differ from HCs. In both groups neural activity during reward anticipation was negatively correlated with harm avoidance.

CONCLUSIONS

Our results show that rMDD is characterized by hyperactivation in fronto-limbic regions during reward anticipation. Alterations in neural activation during reward processing might reflect an increased effort in remitted depressed individuals to allocate neural activity for executive and evaluative processes during anticipatory reward processing.

Genomic architecture of human neuroanatomical diversity

Human brain anatomy is strikingly diverse and highly inheritable: genetic factors may explain up to 80% of its variability. Prior studies have tried to detect genetic variants with a large effect on neuroanatomical diversity, but those currently identified account for <5% of the variance. Here, based on our analyses of neuroimaging and whole-genome genotyping data from 1765 subjects, we show that up to 54% of this heritability is captured by large numbers of single-nucleotide polymorphisms of small-effect spread throughout the genome, especially within genes and close regulatory regions. The genetic bases of neuroanatomical diversity appear to be relatively independent of those of body size (height), but shared with those of verbal intelligence scores. The study of this genomic architecture should help us better understand brain evolution and disease.

Resilience and corpus callosum microstructure in adolescence

BACKGROUND

Resilience is the capacity of individuals to resist mental disorders despite exposure to stress. Little is known about its neural underpinnings. The putative variation of white-matter microstructure with resilience in adolescence, a critical period for brain maturation and onset of high-prevalence mental disorders, has not been assessed by diffusion tensor imaging (DTI). Lower fractional anisotropy (FA) though, has been reported in the corpus callosum (CC), the brain's largest white-matter structure, in psychiatric and stress-related conditions. We hypothesized that higher FA in the CC would characterize stress-resilient adolescents.

METHOD

Three groups of adolescents recruited from the community were compared: resilient with low risk of mental disorder despite high exposure to lifetime stress (n = 55), at-risk of mental disorder exposed to the same level of stress (n = 68), and controls (n = 123). Personality was assessed by the NEO-Five Factor Inventory (NEO-FFI). Voxelwise statistics of DTI values in CC were obtained using tract-based spatial statistics. Regional projections were identified by probabilistic tractography.

RESULTS

Higher FA values were detected in the anterior CC of resilient compared to both non-resilient and control adolescents. FA values varied according to resilience capacity. Seed regional changes in anterior CC projected onto anterior cingulate and frontal cortex. Neuroticism and three other NEO-FFI factor scores differentiated non-resilient participants from the other two groups.

CONCLUSION

High FA was detected in resilient adolescents in an anterior CC region projecting to frontal areas subserving cognitive resources. Psychiatric risk was associated with personality characteristics. Resilience in adolescence may be related to white-matter microstructure.

BDNF Val66Met and reward-related brain function in adolescents: role for early alcohol consumption

Changes in reward processing have been identified as one important pathogenetic mechanism in alcohol addiction. The nonsynonymous single nucleotide polymorphism in the brain-derived neurotrophic factor (BDNF) gene (rs6265/Val66Met) modulates the central nervous system activity of neurotransmitters involved in reward processing such as serotonin, dopamine, and glutamate. It was identified as crucial for alcohol consumption in healthy adults and, in rats, specifically related to the function in the striatum, a region that is commonly involved in reward processing. However, studies in humans on the association of BDNF Val66Met and reward-related brain functions and its role for alcohol consumption, a significant predictor of later alcohol addiction, are missing. Based on an intermediate phenotype approach, we assessed the early orientation toward alcohol and alcohol consumption in 530 healthy adolescents that underwent a monetary incentive delay task during functional magnetic resonance imaging. We found a significantly lower response in the putamen to reward anticipation in adolescent Met carriers with high versus low levels of alcohol consumption. During reward feedback, Met carriers with low putamen reactivity were significantly more likely to orient toward alcohol and to drink alcohol 2 years later. This study indicates a possible effect of BDNF Val66Met on alcohol addiction-related phenotypes in adolescence.

Single nucleotide polymorphism in the neuroplastin locus associates with cortical thickness and intellectual ability in adolescents

Despite the recognition that cortical thickness is heritable and correlates with intellectual ability in children and adolescents, the genes contributing to individual differences in these traits remain unknown. We conducted a large-scale association study in 1583 adolescents to identify genes affecting cortical thickness. Single-nucleotide polymorphisms (SNPs; n=54,837) within genes whose expression changed between stages of growth and differentiation of a human neural stem cell line were selected for association analyses with average cortical thickness. We identified a variant, rs7171755, associating with thinner cortex in the left hemisphere (P=1.12 × 10(-)(7)), particularly in the frontal and temporal lobes. Localized effects of this SNP on cortical thickness differently affected verbal and nonverbal intellectual abilities. The rs7171755 polymorphism acted in cis to affect expression in the human brain of the synaptic cell adhesion glycoprotein-encoding gene NPTN. We also found that cortical thickness and NPTN expression were on average higher in the right hemisphere, suggesting that asymmetric NPTN expression may render the left hemisphere more sensitive to the effects of NPTN mutations, accounting for the lateralized effect of rs7171755 found in our study. Altogether, our findings support a potential role for regional synaptic dysfunctions in forms of intellectual deficits.

Genetic risk for nicotine dependence in the cholinergic system and activation of the brain reward system in healthy adolescents

Genetic variation in a genomic region on chromosome 15q25.1, which encodes the alpha5, alpha3, and beta4 subunits of the cholinergic nicotinic receptor genes, confers risk to smoking and nicotine dependence (ND). Neural reward-related responses have previously been identified as important factors in the development of drug dependence involving ND. Applying an imaging genetics approach in two cohorts (N=487; N=478) of healthy non-smoking adolescents, we aimed to elucidate the impact of genome-wide significant smoking-associated variants in the CHRNA5-CHRNA3-CHRNB4 gene cluster on reward-related neural responses in central regions such as the striatum, orbitofrontal and anterior cingulate cortex (ACC), and personality traits related to addiction. In both samples, carriers of the rs578776 GG compared with AG/AA genotype showed a significantly lower neural response to reward outcomes in the right ventral and dorsal ACC but not the striatum or the orbitofrontal cortex. Rs578776 was unrelated to neural reward anticipation or reward magnitude. Significantly higher scores of anxiety sensitivity in GG compared with AG/AA carriers were found only in sample 1. Associations with other personality traits were not observed. Our findings suggest that the rs578776 risk variant influences susceptibility to ND by dampening the response of the ACC to reward feedback, without recruiting the striatum or orbitofrontal cortex during feedback or anticipation. Thus, it seems to have a major role in the processing of and behavioral adaptation to changing reward outcomes.

[Phantom limb pain. Psychological treatment strategies]

Similar to other pain syndromes phantom limb pain is characterized by learning and memory processes that maintain the pain and increase maladaptive plastic changes of the brain: therefore, psychological interventions that change maladaptive memory processes are useful. In addition to traditional psychological interventions, such as pain management training and biofeedback, more recent developments that involve sensory discrimination training, mirror treatment, graded motor imagery, prosthesis training and training in virtual reality are interesting. These interventions not only reduce phantom limb pain but also reverse the associated maladaptive brain changes.

Maternal interpersonal affiliation is associated with adolescents' brain structure and reward processing

Considerable animal and human research has been dedicated to the effects of parenting on structural brain development, focusing on hippocampal and prefrontal areas. Conversely, although functional imaging studies suggest that the neural reward circuitry is involved in parental affection, little is known about mothers' interpersonal qualities in relation to their children's brain structure and function. Moreover, gender differences concerning the effect of maternal qualities have rarely been investigated systematically. In 63 adolescents, we assessed structural and functional magnetic resonance imaging as well as interpersonal affiliation in their mothers. This allowed us to associate maternal affiliation with gray matter density and neural responses during different phases of the well-established Monetary Incentive Delay task. Maternal affiliation was positively associated with hippocampal and orbitofrontal gray matter density. Moreover, in the feedback of reward hit as compared with reward miss, an association with caudate activation was found. Although no significant gender effects were observed in these associations, during reward feedback as compared with baseline, maternal affiliation was significantly associated with ventral striatal and caudate activation only in females. Our findings demonstrate that maternal interpersonal affiliation is related to alterations in both the brain structure and reward-related activation in healthy adolescents. Importantly, the pattern is in line with typical findings in depression and post-traumatic stress disorder, suggesting that a lack of maternal affiliation might have a role in the genesis of mental disorders.

Brain activation during fear conditioning in humans depends on genetic variations related to functioning of the hypothalamic-pituitary-adrenal axis: first evidence from two independent subsamples

BACKGROUND

Enhanced acquisition and delayed extinction of fear conditioning are viewed as major determinants of anxiety disorders, which are often characterized by a dysfunctional hypothalamic-pituitary-adrenal (HPA) axis.

METHOD

In this study we employed cued fear conditioning in two independent samples of healthy subjects (sample 1: n=60, sample 2: n=52). Two graphical shapes served as conditioned stimuli and painful electrical stimulation as the unconditioned stimulus. In addition, guided by findings from published animal studies on HPA axis-related genes in fear conditioning, we examined variants of the glucocorticoid receptor and corticotropin-releasing hormone receptor 1 genes.

RESULTS

Variation in these genes showed enhanced amygdala activation during the acquisition and reduced prefrontal activation during the extinction of fear as well as altered amygdala-prefrontal connectivity.

CONCLUSIONS

This is the first demonstration of the involvement of genes related to the HPA axis in human fear conditioning.

Boys do it the right way: sex-dependent amygdala lateralization during face processing in adolescents

Previous studies have observed a sex-dependent lateralization of amygdala activation related to emotional memory. Specifically, it was shown that the activity of the right amygdala correlates significantly stronger with memory for images judged as arousing in men than in women, and that there is a significantly stronger relationship in women than in men between activity of the left amygdala and memory for arousing images. Using a large sample of 235 male adolescents and 235 females matched for age and handedness, we investigated the sex-specific lateralization of amygdala activation during an emotional face perception fMRI task. Performing a formal sex by hemisphere analysis, we observed in males a significantly stronger right amygdala activation as compared to females. Our results indicate that adolescents display a sex-dependent lateralization of amygdala activation that is also present in basic processes of emotional perception. This finding suggests a sex-dependent development of human emotion processing and may further implicate possible etiological pathways for mental disorders most frequent in adolescent males (i.e., conduct disorder).

Quantitative sensory testing in the German Research Network on Neuropathic Pain (DFNS): somatosensory abnormalities in 1236 patients with different neuropathic pain syndromes

Neuropathic pain is accompanied by both positive and negative sensory signs. To explore the spectrum of sensory abnormalities, 1236 patients with a clinical diagnosis of neuropathic pain were assessed by quantitative sensory testing (QST) following the protocol of DFNS (German Research Network on Neuropathic Pain), using both thermal and mechanical nociceptive as well as non-nociceptive stimuli. Data distributions showed a systematic shift to hyperalgesia for nociceptive, and to hypoesthesia for non-nociceptive parameters. Across all parameters, 92% of the patients presented at least one abnormality. Thermosensory or mechanical hypoesthesia (up to 41%) was more frequent than hypoalgesia (up to 18% for mechanical stimuli). Mechanical hyperalgesias occurred more often (blunt pressure: 36%, pinprick: 29%) than thermal hyperalgesias (cold: 19%, heat: 24%), dynamic mechanical allodynia (20%), paradoxical heat sensations (18%) or enhanced wind-up (13%). Hyperesthesia was less than 5%. Every single sensory abnormality occurred in each neurological syndrome, but with different frequencies: thermal and mechanical hyperalgesias were most frequent in complex regional pain syndrome and peripheral nerve injury, allodynia in postherpetic neuralgia. In postherpetic neuralgia and in central pain, subgroups showed either mechanical hyperalgesia or mechanical hypoalgesia. The most frequent combinations of gain and loss were mixed thermal/mechanical loss without hyperalgesia (central pain and polyneuropathy), mixed loss with mechanical hyperalgesia in peripheral neuropathies, mechanical hyperalgesia without any loss in trigeminal neuralgia. Thus, somatosensory profiles with different combinations of loss and gain are shared across the major neuropathic pain syndromes. The characterization of underlying mechanisms will be needed to make a mechanism-based classification feasible.

The IMAGEN study: reinforcement-related behaviour in normal brain function and psychopathology

A fundamental function of the brain is to evaluate the emotional and motivational significance of stimuli and to adapt behaviour accordingly. The IMAGEN study is the first multicentre genetic-neuroimaging study aimed at identifying the genetic and neurobiological basis of individual variability in impulsivity, reinforcer sensitivity and emotional reactivity, and determining their predictive value for the development of frequent psychiatric disorders. Comprehensive behavioural and neuropsychological characterization, functional and structural neuroimaging and genome-wide association analyses of 2000 14-year-old adolescents are combined with functional genetics in animal and human models. Results will be validated in 1000 adolescents from the Canadian Saguenay Youth Study. The sample will be followed up longitudinally at the age of 16 years to investigate the predictive value of genetics and intermediate phenotypes for the development of frequent psychiatric disorders. This review describes the strategies the IMAGEN consortium used to meet the challenges posed by large-scale multicentre imaging-genomics investigations. We provide detailed methods and Standard Operating Procedures that we hope will be helpful for the design of future studies. These include standardization of the clinical, psychometric and neuroimaging-acquisition protocols, development of a central database for efficient analyses of large multimodal data sets and new analytic approaches to large-scale genetic neuroimaging analyses.

NMDA-receptor antagonist and morphine decrease CRPS-pain and cerebral pain representation

A combination therapy of morphine with an NMDA-receptor antagonist might be more effective than morphine without a NMDA-receptor antagonist for the relief of neuropathic pain in patients with complex regional pain syndrome (CRPS). In order to test the efficacy of this combination therapy we performed a double-blind randomized placebo-controlled study on patients suffering from CRPS of the upper extremity. We used functional magnetic resonance imaging during movement of the affected and unaffected upper hand before and after a treatment regimen of 49 days that contrasted morphine and an NMDA-receptor antagonist with morphine and placebo. We postulated superior pain relief for the combination therapy and concomitant changes in brain areas associated with nociceptive processing. Only the combination therapy reduced pain at rest and during movement, and disability. After treatment, activation in the contralateral primary somatosensory (cS1) and anterior cingulate cortex was significantly reduced when the affected hand was moved. Pain relief during therapy was related to decreased activation in cS1 and secondary somatosensory cortex (S2). Our data suggest that the combination of morphine with an NMDA-receptor antagonist significantly affects the cerebral processing of nociceptive information in CRPS. The correlation of pain relief and decrease in cortical activity in cS1 and S2 is in accordance with the expected impact of the NMDA-receptor antagonist on cerebral pain processing with emphasis on sensory-discriminative aspects of pain.

The influence of the 5‐HT3receptor antagonist tropisetron on pain in fibromyalgia: a functional magnetic resonance imaging pilot study

OBJECTIVE

Central pain processing is altered in patients with fibromyalgia syndrome (FMS). The serotonin metabolism, especially the 5-HT3 receptor, seems to play an important role.

METHODS

We investigated the effect of the local injection of the 5-HT3 receptor antagonist tropisetron on the perception and central processing of pain in FMS patients using painful mechanical stimulation and functional magnetic resonance imaging (fMRI) within the framework of a pre-/posttreatment double-blind design.

RESULTS

In the contralateral primary somatosensory cortex, contralateral posterior insula, and anterior cingulate cortex, we found that the activation was significantly reduced after treatment. On average, patients rated the stimulation-induced pain intensity as stronger in the session after treatment compared to before treatment, although the individual data revealed a heterogeneous pattern. All patients showed sensitisation during the painful stimulation, which was not influenced by the treatment.

CONCLUSIONS

Both the sensory-discriminative and motivational-affective components of pain as measured by fMRI were altered by tropisetron.

Effects of stressor controllability on psychophysiological, cognitive and behavioural responses in patients with major depression and dysthymia

BACKGROUND

The experience of uncontrollability and helplessness in the face of stressful life events is regarded as an important determinant in the development and maintenance of depression. The inability to successfully deal with stressors might be linked to dysfunctional prefrontal functioning. We assessed cognitive, behavioural and physiological effects of stressor uncontrollability in depressed and healthy individuals. In addition, relationships between altered cortical processing and cognitive vulnerability traits of depression were analysed.

METHOD

A total of 26 unmedicated depressed patients and 24 matched healthy controls were tested in an expanded forewarned reaction (S1-S2) paradigm. In a factorial design, stressor controllability varied across three consecutive conditions: (a) control, (b) loss of control and (c) restitution of control. Throughout the experiment, error rates, ratings of controllability, arousal, emotional valence and helplessness were assessed together with the post-imperative negative variation (PINV) of the electroencephalogram.

RESULTS

Depressed participants showed an enhanced frontal PINV as an electrophysiological index of altered information processing during both loss of control and restitution of control. They also felt more helpless than controls. Furthermore, frontal PINV magnitudes were associated with habitual rumination in the depressed subsample.

CONCLUSIONS

These findings indicate that depressed patients are more susceptible to stressor uncontrollability than healthy subjects. Moreover, the experience of uncontrollability seems to bias subsequent information processing in a situation where control is objectively re-established. Alterations in prefrontal functioning appear to contribute to this vulnerability and are also linked to trait markers of depression.

Phantom limb pain: cortical plasticity and novel therapeutic approaches

Phantom limb pain is still a very frequent consequence of peripheral deafferentation or amputation of a limb. Recent findings from animal and neuroimaging studies suggest that phantom limb pain might be a central phenomenon, related to changes in the cortical, thalamic and spinal representation of the painful limb, and might be a type of somatosensory pain memory. Based on these assumptions, new treatment approaches focus on sensory discrimination training or motor cortex stimulation in an effort to influence cortical reorganization. Prevention of perpetuation of a somatosensory pain memory might also be possible through pharmacological agents such as N-methyl-D-aspartate antagonists and gamma-aminobutyric acid agonists, substances that have been shown to influence and prevent cortical reorganization.

Gene-gene effects on central processing of aversive stimuli

Emotional reactivity and regulation are fundamental to human behavior. As inter-individual behavioral variation is affected by a multitude of different genes, there is intense interest to investigate gene-gene effects. Functional sequence variation at two genes has been associated with response and resiliency to emotionally unpleasant stimuli. These genes are the catechol-O-methyltransferase gene (COMT Val158Met) and the regulatory region (5-HTTLPR) of the serotonin transporter gene. Recently, it has been proposed that 5-HTT expression is not only affected by the common S/L variant of 5-HTTLPR but also by an A to G substitution. Using functional magnetic resonance imaging, we assessed the effects of COMT Val(158)Met and both 5-HTT genotypes on brain activation by standardized affective visual stimuli (unpleasant, pleasant, and neutral) in 48 healthy subjects. Based on previous studies, the analysis of genotype effects was restricted to limbic brain areas. To determine allele-dose effects, the number of COMT Met158 alleles (i.e., lower activity of COMT) and the number of 5-HTT low expressing alleles (S and G) was correlated with the blood oxygen level-dependent (BOLD) response to pleasant or unpleasant stimuli compared to neutral stimuli. We observed an additive effect of COMT and both 5-HTT polymorphisms, accounting for 40% of the inter-individual variance in the averaged BOLD response of amygdala, hippocampal and limbic cortical regions elicited by unpleasant stimuli. Effects of 5-HTT and COMT genotypes did not affect brain processing of pleasant stimuli. These data indicate that functional brain imaging may be used to assess the interaction of multiple genes on the function of neuronal networks.

Limitations of pharmacotherapy: behavioral approaches to chronic pain

Pharmacotherapy is most appropriate in acute pain, whereas in chronic pain states behavioral approaches or a combination of behavioral treatment and pharmacotherapy is more appropriate. In this chapter we first describe the role of learning and memory as well as other psychological factors in the development of chronic pain and emphasize that chronic pain must viewed as the result of a learning process with resulting central neuroplastic changes. We then describe operant behavioral and cognitive-behavioral treatments as well as biofeedback and relaxation techniques and present innovative treatment procedures aimed at altering central pain memories. We complete the section with a discussion of combined behavioral and pharmacological approaches and an interdisciplinary view.

Consensus for tinnitus patient assessment and treatment outcome measurement: Tinnitus Research Initiative meeting, Regensburg, July 2006

There is widespread recognition that consistency between research centres in the ways that patients with tinnitus are assessed and outcomes following interventions are measured would facilitate more effective co-operation and more meaningful evaluations and comparisons of outcomes. At the first Tinnitus Research Initiative meeting held in Regensburg in July 2006 an attempt was made through workshops to gain a consensus both for patient assessments and for outcome measurements. It is hoped that this will contribute towards better cooperation between research centres in finding and evaluating treatments for tinnitus by allowing better comparability between studies.