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Neurobiology of Pain (Cambridge, Mass.) 2023Chronic pain (CP) is a leading cause of disability worldwide. Pain may be measured using subjective questionnaires, but understanding the underlying physiology, such as... (Review)
Review
INTRODUCTION
Chronic pain (CP) is a leading cause of disability worldwide. Pain may be measured using subjective questionnaires, but understanding the underlying physiology, such as brain function, could improve prognosis. Further, there has been a shift towards cost-effective lifestyle modification for the management of CP.
METHODS
We conducted a systematic review (Registration: #CRD42022331870) using articles retrieved from four databases (Pubmed, EMBASE, AMED, and CINAHL) to assess the effect of exercise on brain function and pain perception/quality of life in adults with CP.
RESULTS
Our search yielded 1879 articles; after exclusion, ten were included in the final review. Study participants were diagnosed with either osteoarthritis or fibromyalgia. However, two studies included "fibromyalgia and low back pain" or "fibromyalgia, back, and complex regional pain." Exercise interventions that were 12 weeks or longer (n = 8/10) altered brain function and improved pain and/or quality of life outcomes. The cortico-limbic pathway, default-mode network, and dorsolateral prefrontal cortex were key regions that experienced alterations post-intervention. All studies that reported an improvement in brain function also demonstrated an improvement in pain perception and/or quality of life.
DISCUSSION
Our review suggests that alterations in brain function, notably the cortico-limbic, default-mode and dorsolateral prefrontal cortex, may be responsible for the downstream improvements in the subjective experience of CP. Through appropriate programming (i.e., length of intervention), exercise may represent a viable option to manage CP via its positive influence on brain health.
PubMed: 37206154
DOI: 10.1016/j.ynpai.2023.100129 -
Behavioural Brain Research Feb 2023Post-stroke cognitive impairment (PSCI) is one of the common symptoms in stroke survivors, by which their quality of life and rehabilitation progress are severely... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
Post-stroke cognitive impairment (PSCI) is one of the common symptoms in stroke survivors, by which their quality of life and rehabilitation progress are severely limited. Repetitive transcranial magnetic stimulation (rTMS) has been proven to regulate cognition in a non-invasive way. However, the inconsistency in its effectiveness on PSCI reported in previous studies cannot be ruled out. A critical and comprehensive systematic review of rTMS on PSCI patients is necessary.
METHODS
Trials published before the end of February 2022 on rTMS and PSCI were systematically retrieved from PubMed, Cochrane Library, EBSCO, Embase and SCOPUS. High-quality literature was selected following the inclusion and exclusion criteria, with their references being screened. Meta-analysis of data was carried out using RevMan 5.4 software.
RESULTS
Ten trials involving 347 participants were included in the current review. Global cognition as measured by MMSE or MoCA (SMD=0.54; 95% CI=0.31, 0.76; P < 0.00001; I = 38%) and modified Barthel index (MD=9.00; 95% CI=2.93, 15.06; P = 0.004; I = 0%) were significantly improved by rTMS compared to sham stimulation in PSCI patients. Performance of the digit symbol test, rivermead behavioral memory test and attention in PSCI patients were also significantly improved. Subgroup analyses showed that significant differences were found in both MoCA and MMSE among PSCI patients by rTMS. MoCA was significantly improved by high frequency rTMS, while both MoCA and MMSE were significantly improved targeting on left dorsolateral prefrontal cortex.
CONCLUSION
rTMS provides a non-invasive and effective technique for the treatment of post-stroke patients with cognitive impairment.
Topics: Humans; Transcranial Magnetic Stimulation; Quality of Life; Cognitive Dysfunction; Stroke; Cognition
PubMed: 36442646
DOI: 10.1016/j.bbr.2022.114229 -
Brain Stimulation 2021High-frequency rTMS over the dorsolateral prefrontal cortex (DLPFC) has demonstrated mixed effects on chronic and provoked pain. (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
High-frequency rTMS over the dorsolateral prefrontal cortex (DLPFC) has demonstrated mixed effects on chronic and provoked pain.
OBJECTIVES/METHODS
In this study, a meta-analysis was conducted to characterise the potential analgesic effects of high-frequency rTMS over the DLPFC on both chronic and provoked pain.
RESULTS
A total of 626 studies were identified in a systematic search. Twenty-six eligible studies were included for the quantitative review, among which 17 modulated chronic pain and the remaining investigated the influence on provoked pain. The left side DLPFC was uniformly targeted in the chronic pain studies. While our data identified no overall effect of TMS across chronic pain conditions, there was a significant short-term analgesia in neuropathic pain conditions only (SMD = -0.87). In terms of long-lasting analgesia, there was an overall pain reduction in the midterm (SMD = -0.53, 24.6 days average) and long term (SMD = -0.63, 3 months average) post DLPFC stimulation, although these effects were not observed within specific chronic pain conditions. Surprisingly, the number of sessions was demonstrated to have no impact on rTMS analgesia. In the analysis of provoked pain, our data also indicated a significant analgesic effect following HF-rTMS over the DLPFC (SMD = -0.73). Importantly, we identified a publication bias in the studies of provoked pain but not for chronic pain conditions.
CONCLUSIONS
Overall, our findings support that HF-DLPFC stimulation is able to induce an analgesic effect in chronic pain and in response to provoked pain. These results highlight the potential of DLPFC-rTMS in the management of certain chronic pain conditions and future directions are discussed to enhance the potential long-term analgesic effects.
Topics: Chronic Pain; Humans; Pain Management; Pain Measurement; Prefrontal Cortex; Transcranial Magnetic Stimulation
PubMed: 34280583
DOI: 10.1016/j.brs.2021.07.004 -
Frontiers in Integrative Neuroscience 2021Delusions are marked, fixed beliefs that are incongruent with reality. Delusions, with comorbid hallucinations, are a hallmark of certain psychotic disorders (e.g.,...
Delusions are marked, fixed beliefs that are incongruent with reality. Delusions, with comorbid hallucinations, are a hallmark of certain psychotic disorders (e.g., schizophrenia). Delusions can present transdiagnostically, in neurodegenerative (e.g., Alzheimer's disease and fronto-temporal dementia), nervous system disorders (e.g., Parkinson's disease) and across other psychiatric disorders (e.g., bipolar disorder). The burden of delusions is severe and understanding the heterogeneity of delusions may delineate a more valid nosology of not only psychiatric disorders but also neurodegenerative and nervous system disorders. We systematically reviewed structural neuroimaging studies reporting on delusions in four disorder types [schizophrenia (SZ), bipolar disorder (BP), Alzheimer's disease (AD), and Parkinson's disease (PD)] to provide a comprehensive overview of neural changes and clinical presentations associated with delusions. Twenty-eight eligible studies were identified. This review found delusions were most associated with gray matter reductions in the dorsolateral prefrontal cortex (SZ, BP, and AD), left claustrum (SZ and AD), hippocampus (SZ and AD), insula (SZ, BP, and AD), amygdala (SZ and BP), thalamus (SZ and AD), superior temporal gyrus (SZ, BP, and AD), and middle frontal gyrus (SZ, BP, AD, and PD). However, there was a great deal of variability in the findings of each disorder. There is some support for the current dopaminergic hypothesis of psychosis, but we also propose new hypotheses related to the belief formation network and cognitive biases. We also propose a standardization of assessments to aid future transdiagnostic study approaches. Future studies should explore the neural and biological underpinnings of delusions to hopefully, inform future treatment.
PubMed: 35140591
DOI: 10.3389/fnint.2021.726321 -
Brain and Cognition Apr 2014Recent studies have used non-invasive brain stimulation (NIBS) techniques, such as repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current... (Meta-Analysis)
Meta-Analysis Review
Recent studies have used non-invasive brain stimulation (NIBS) techniques, such as repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS), to increase dorsolateral prefrontal cortex (DLPFC) activity and, consequently, working memory (WM) performance. However, such experiments have yielded mixed results, possibly due to small sample sizes and heterogeneity of outcomes. Therefore, our aim was to perform a systematic review and meta-analyses on NIBS studies assessing the n-back task, which is a reliable index for WM. From the first data available to February 2013, we looked for sham-controlled, randomized studies that used NIBS over the DLPFC using the n-back task in PubMed/MEDLINE and other databases. Twelve studies (describing 33 experiments) matched our eligibility criteria. Active vs. sham NIBS was significantly associated with faster response times (RTs), higher percentage of correct responses and lower percentage of error responses. However, meta-regressions showed that tDCS (vs. rTMS) presented only an improvement in RT, and not in accuracy. This could have occurred in part because almost all tDCS studies employed a crossover design, possibly due to the reliable tDCS blinding. Study design was also associated with no improvement in correct responses in the active vs. sham groups. To conclude, rTMS of the DLPFC significantly improved all measures of WM performance whereas tDCS significantly improved RT, but not the percentage of correct and error responses. Mechanistic insights on the role of DLPFC in WM are further discussed, as well as how NIBS techniques could be used in neuropsychiatric samples presenting WM deficits, such as major depression, dementia and schizophrenia.
Topics: Electric Stimulation; Female; Humans; Male; Memory, Short-Term; Prefrontal Cortex; Transcranial Magnetic Stimulation
PubMed: 24514153
DOI: 10.1016/j.bandc.2014.01.008 -
International Journal of Geriatric... Dec 2014Late-life depression (LLD) is the association with more cerebrovascular susceptibilities and white matter damage that can be assessed with diffusion tensor imaging... (Meta-Analysis)
Meta-Analysis Review
OBJECTIVES
Late-life depression (LLD) is the association with more cerebrovascular susceptibilities and white matter damage that can be assessed with diffusion tensor imaging (DTI). To better understand the white matter pathological alterations in LLD, we conducted a systematic review and meta-analysis.
METHODS
We searched MEDLINE, EMBASE, PsycINFO, PubMed, and Google Scholar databases for DTI studies comparing patients with LLD and healthy controls. For each study, details regarding participants, imaging methods, and results were extracted. Fractional anisotropy, an index of white matter integrity, was the dependent variable for group comparison. Effect sizes indicating the degree of group difference were estimated by random-effects meta-analysis.
RESULTS
A total of 15 eligible studies were included in the qualitative systematic review, nine of which were suitable for quantitative meta-analyses for the dorsolateral prefrontal cortex (DLPFC), corpus callosum, cingulum, and uncinate fasciculus (UF). Compared with the healthy control group, the LLD group showed lower fractional anisotropy in the DLPFC and UF with a large and a medium effect size, respectively, although heterogeneity and publication bias were found in the DLPFC.
CONCLUSION
Diffusion tensor imaging studies of LLD consistently showed reduced anisotropy in the DLPFC and UF of patients with LLD. These damaged regions are located with the frontostriatal and limbic networks. Thus, our findings showed that the disruption of frontal and frontal-to-limbic white matter tracts contributes to the pathogenesis of LLD.
Topics: Aged; Anisotropy; Case-Control Studies; Depressive Disorder; Diffusion Tensor Imaging; Frontal Lobe; Humans; Limbic System; White Matter
PubMed: 24798480
DOI: 10.1002/gps.4129 -
Current Psychiatry Reports May 2014Borderline personality disorder (BPD) is a common psychiatric disorder, the core features of which are affective dysregulation, identity disturbances, and problems in... (Review)
Review
Borderline personality disorder (BPD) is a common psychiatric disorder, the core features of which are affective dysregulation, identity disturbances, and problems in social interaction, with an intense fear of loss, abandonment, or rejection by social partners. Self-injurious behaviors (SIB), such as superficial cutting, occur in 70-80 % of BPD patients, which are associated with emotional relief. Intriguingly, the majority of BPD patients report reduced or no pain associated with SIB, whereas BPD patients are over-represented in chronic pain patients. Thus, studying pain perception in such patients may help to understand the pathophysiology of BPD, but also the interaction between affective and physical dimensions of pain. We conducted a systematic review dealing with physical and social pains in BPD patients, with a special focus on neuroimaging data. SIB appear to be an inadequate strategy to regulate negative emotions that may be related to social/psychological pain, by increasing dorsolateral prefrontal cortex activation in order to regulate amygdala activation. In addition, abnormal hyperactivation of the insula is a possible trait marker of BPD, and might contribute to modified pain sensitivity. When considering psychological pain in BPD patients, neuroanatomical studies have shown a hyper-responsive subcortical limbic network and a deficient regulatory control system operating through anterior brain regions. Promising therapeutic strategies should target neuroanatomical and neurobiological dysfunctions, which lead to altered pain perception in BPD patients.
Topics: Amygdala; Borderline Personality Disorder; Brain; Brain Mapping; Humans; Pain; Pain Threshold; Self-Injurious Behavior; Stress, Psychological
PubMed: 24633938
DOI: 10.1007/s11920-014-0443-2 -
Journal of Psychiatric Research Mar 2014While there is evidence of clinical improvement of posttraumatic stress disorder (PTSD) with treatment, its neural underpinnings are insufficiently clear. Moreover, it... (Review)
Review
While there is evidence of clinical improvement of posttraumatic stress disorder (PTSD) with treatment, its neural underpinnings are insufficiently clear. Moreover, it is unknown whether similar neurophysiological changes occur in PTSD specifically after child abuse, given its enduring nature and the developmental vulnerability of the brain during childhood. We systematically reviewed PTSD treatment effect studies on structural and functional brain changes from PubMed, EMBASE, PsycINFO, PILOTS and the Cochrane Library. We included studies on adults with (partial) PTSD in Randomized Controlled Trials (RCT) or pre-post designs (excluding case studies) on pharmacotherapy and psychotherapy. Risk of bias was evaluated independently by two raters. Brain coordinates and effect sizes were standardized for comparability. We included 15 studies (6 RCTs, 9 pre-post), four of which were on child abuse. Results showed that pharmacotherapy improved structural abnormalities (i.e., increased hippocampus volume) in both adult-trauma and child abuse related PTSD (3 pre-post studies). Functional changes were found to distinguish between groups. Adult-trauma PTSD patients showed decreased amygdala and increased dorsolateral prefrontal activations post-treatment (4 RCTs, 5 pre-post studies). In one RCT, child abuse patients showed no changes in the amygdala, but decreased dorsolateral prefrontal, dorsal anterior cingulate and insula activation post-treatment. In conclusion, pharmacotherapy may reduce structural abnormalities in PTSD, while psychotherapy may decrease amygdala activity and increase prefrontal, dorsal anterior cingulate and hippocampus activations, that may relate to extinction learning and re-appraisal. There is some evidence for a distinct activation pattern in child abuse patients, which clearly awaits further empirical testing.
Topics: Adult; Animals; Brain; Child; Child Abuse; Humans; Neuronal Plasticity; Psychotherapy; Stress Disorders, Post-Traumatic
PubMed: 24321592
DOI: 10.1016/j.jpsychires.2013.11.002 -
Biological Psychiatry. Cognitive... Feb 2023Treatments for cognitive dysfunction in neuropsychiatric conditions are urgently needed. Cognitive training and transcranial direct current stimulation (tDCS) hold... (Meta-Analysis)
Meta-Analysis
BACKGROUND
Treatments for cognitive dysfunction in neuropsychiatric conditions are urgently needed. Cognitive training and transcranial direct current stimulation (tDCS) hold promise, and there is growing interest in combined or multimodal treatments, though studies to date have had small samples and inconsistent results.
METHODS
A systematic review and meta-analysis was completed. Retained studies included cognitive training combined with active or sham tDCS in a neuropsychiatric population and reported a posttreatment cognitive outcome. Meta-analyses included effect sizes comparing cognitive training plus active tDCS and cognitive training plus sham tDCS in 5 cognitive domains. Risk of bias in included studies and across studies was explored.
RESULTS
Fifteen studies were included: 10 in neurodegenerative disorders and 5 in psychiatric disorders (n = 629). There were several tDCS montages, though two-thirds of studies placed the anode over the left dorsolateral prefrontal cortex. A wide variety of cognitive training types and outcome measures were reported. There was a small, statistically significant effect of combined treatment on measures of attention/working memory, as well as small and non-statistically significant effects favoring combined treatment on global cognition and language. There was no evidence of bias in individual studies but some evidence of nonreporting or small-study bias across studies.
CONCLUSIONS
These results may provide preliminary support for the efficacy of combined cognitive training and tDCS on measures of attention/working memory. More data are needed, particularly via studies that explicitly align the cognitive ability of interest, stimulation target, training type, and outcome measures.
Topics: Humans; Transcranial Direct Current Stimulation; Cognitive Training; Prefrontal Cortex; Cognition; Memory, Short-Term
PubMed: 36653210
DOI: 10.1016/j.bpsc.2022.09.014 -
Journal of Clinical Medicine May 2023Gambling disorder (GD) and internet gaming disorder (IGD) are formally recognized behavioral addictions with a rapidly growing prevalence and limited treatment options.... (Review)
Review
Effects of Transcranial Electrical Stimulation on Gambling and Gaming: A Systematic Review of Studies on Healthy Controls, Participants with Gambling/Gaming Disorder, and Substance Use Disorder.
Gambling disorder (GD) and internet gaming disorder (IGD) are formally recognized behavioral addictions with a rapidly growing prevalence and limited treatment options. Recently, transcranial electrical stimulation (tES) techniques have emerged as potentially promising interventions for improving treatment outcomes by ameliorating cognitive functions implicated in addictive behaviors. To systematize the current state of evidence and better understand whether and how tES can influence gambling and gaming-related cognitive processes, we conducted a PRISMA-guided systematic review of the literature, focusing on tES effects on gaming and gambling in a diverse range of population samples, including healthy participants, participants with GD and IGD, as well as participants with substance abuse addictions. Following the literature search in three bibliographic databases (PubMed, Web of Science, and Scopus), 40 publications were included in this review, with 26 conducted on healthy participants, 6 focusing on GD and IGD patients, and 8 including participants with other addictions. Most of the studies targeted the dorsolateral prefrontal cortex, using transcranial direct current stimulation (tDCS), and assessed the effects on cognition, using gaming and gambling computerized cognitive tasks measuring risk taking and decision making, e.g., balloon analogue risk task, Iowa gambling task, Cambridge gambling task, etc. The results indicated that tES could change gambling and gaming task performances and positively influence GD and IGD symptoms, with 70% of studies showing neuromodulatory effects. However, the results varied considerably depending on the stimulation parameters, sample characteristics, as well as outcome measures used. We discuss the sources of this variability and provide further directions for the use of tES in the context of GD and IGD treatment.
PubMed: 37240512
DOI: 10.3390/jcm12103407