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Journal of Neurology Mar 2022Persistent Postural-Perceptual Dizziness (PPPD) is one of the most common types of chronic dizziness. The pathogenesis remains unclear. (Review)
Review
BACKGROUND
Persistent Postural-Perceptual Dizziness (PPPD) is one of the most common types of chronic dizziness. The pathogenesis remains unclear.
OBJECTIVE
This study aimed to systematically review neuroimaging literature for investigating the central mechanism of PPPD and related disorders.
METHODS
PubMed, EMBASE, Medline, Cochrane, and Web of Science were searched by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The articles analyzing structural and functional neuroimaging features of PPPD and related disorders were selected according to eligibility criteria.
RESULTS
Fifteen articles, including 4 structural, 10 functional, and 1 multimodal imaging, were eligible for inclusion in this review. The whiter matter alterations in PPPD are not entirely consistent. The changes of grey matter mainly in multisensory vestibular cortices, visual cortex, cerebellum, as well as anxiety-related network. Consistent with structural imaging, functional imaging conducted during the specific tasks or in the resting state has both found abnormal functional activation and connectivity in the vestibular cortex, especially in the parieto-insular vestibular cortex (PIVC), visual cortex, cerebellum, and anxiety-related network in PPPD and related disorder.
CONCLUSIONS
The current review provides up-to-date knowledge and summarizes the possible central mechanism for PPPD and related disorders, and it is helpful to understanding the mechanism of PPPD.
Topics: Cerebral Cortex; Dizziness; Gray Matter; Humans; Mental Disorders; Neuroimaging
PubMed: 34019178
DOI: 10.1007/s00415-021-10558-x -
Journal of Psychiatry & Neuroscience :... Nov 2013Endophenotypes in genetic psychiatry may increase our understanding of the molecular mechanisms underlying disease risk and its manifestations. We sought to investigate... (Review)
Review
BACKGROUND
Endophenotypes in genetic psychiatry may increase our understanding of the molecular mechanisms underlying disease risk and its manifestations. We sought to investigate the link between neuropsychological impairments and brain structural abnormalities associated with the COMT Val(158)Met polymorphism in patients with schizophrenia to improve understanding of the pathophysiology of this disorder.
METHODS
We performed a systematic review using studies identified in PubMed and MEDLINE (from the date of the first available article to July 2012). Our review examined evidence of an association between the COMT Val(158)Met polymorphism and both neuropsychological performance and brain structure in patients with psychosis, in their relatives and in healthy individuals (step 1). The review also explored whether the neuropsychological tasks and brain structures identified in step 1 met the criteria for an endophenotype (step 2). Then we evaluated evidence that the neuropsychological endophenotypes identified in step 2 are associated with the brain structure endophenotypes identified in that step (step 3). Finally, we propose a neurobiological interpretation for this evidence.
RESULTS
A poorer performance on the n-back task and the Continuous Performance Test (CPT) and smaller temporal and frontal brain areas were associated with the COMT Val allele in patients with schizophrenia and their relatives and met most of the criteria for an endophenotype. It is possible that the COMT Val(158)Met polymorphism therefore contributes to the development of these neuropsychological and brain structural endophenotypes of schizophrenia, in which the prefrontal cortex may represent the neural substrate underlying both n-back and CPT performances.
LIMITATIONS
The association between a single genetic variant and an endophenotype does not necessarily imply a causal relationship between them.
CONCLUSION
This evidence and the proposed interpretation contribute to explain, at least in part, the biological substrate of 4 important endophenotypes that characterize schizophrenia.
Topics: Atrophy; Brain; Catechol O-Methyltransferase; Endophenotypes; Frontal Lobe; Genetic Predisposition to Disease; Humans; Neuropsychological Tests; Polymorphism, Single Nucleotide; Psychomotor Performance; Schizophrenia; Schizophrenic Psychology; Temporal Lobe
PubMed: 23527885
DOI: 10.1503/jpn.120178 -
Brain, Behavior, and Immunity Jul 2020Non-convulsive neurostimulation is a rapidly-developing alternative to traditional treatment approaches in depression. Modalities such as repetitive Transcranial... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
Non-convulsive neurostimulation is a rapidly-developing alternative to traditional treatment approaches in depression. Modalities such as repetitive Transcranial Magnetic Stimulation (rTMS), transcranial Direct Current Stimulation (tDCS), Vagal Nerve Stimulation (VNS) and Deep Brain Stimulation (DBS) are now recognized as potential treatments. How non-convulsive neurostimulation interventions impact the neurohormonal and neuroimmune changes that accompany depression remains relatively unknown. If this type of intervention can drive endocrine, immune, as well symptom changes in depression, non-convulsive neurostimulation may represent a viable, multi-faceted treatment approach in depression. We were therefore interested to understand the state of the literature in this developing area.
METHODS
A systematic review of all studies that examined the impact of non-convulsive neurostimulation interventions on the hypothalamic-pituitary-adrenal (HPA) axis and immune function in the form of cytokine production in depression.
RESULTS
We identified 15 human studies, 9 that examined rTMS, 2 that examined tDCS, 2 that examined VNS and 2 that examined electroacupuncture. 11 animal studies were also identified, 3 that examined rTMS, 2 that examined DBS and 6 that examined electroacupuncture. All types of non-convulsive neurostimulation were able to revert the increases in cortisol, ACTH and other components of the HPA axis that are seen in depressed patients, as well as to modulate the levels of key cytokines known to be up-regulated in depression, such as IL-1β, IL-6 and TNF-α. Changes in the HPA axis and levels of cytokines in response to non-convulsive neurostimulation often did not correlate with change in depressive symptoms. Most studies were not controlled trials and thus, significant methodologic variability existed. Furthermore, many human studies lacked a sham stimulation comparator arm. We were unable to conduct relevant meta-analyses due to the design heterogeneities, heterogeneity in the reported outcome measures and the limited number of studies retrieved. Animal studies generally supported the findings of those in human, but again, significant variability in methodology and study design were evident.
CONCLUSIONS
Non-convulsive neurostimulation interventions show promise in their ability to alter the endocrine and immune disturbances that accompany depression. Further research, which includes blinded, sham-controlled comparator designs is required.
Topics: Deep Brain Stimulation; Depression; Humans; Hypothalamo-Hypophyseal System; Pituitary-Adrenal System; Transcranial Direct Current Stimulation
PubMed: 32126288
DOI: 10.1016/j.bbi.2020.02.016 -
Psychiatry Research Apr 2015Posttraumatic stress disorder (PTSD) is a debilitating condition associated with mild to moderate cognitive impairment and with a prevalence rate of up to 22% in... (Meta-Analysis)
Meta-Analysis Review
Posttraumatic stress disorder (PTSD) is a debilitating condition associated with mild to moderate cognitive impairment and with a prevalence rate of up to 22% in veterans. This systematic review and quantitative meta-analysis explore volumetric differences of three key structural brain regions (hippocampus, amygdala and anterior cingulate cortex (ACC)), all of which have been implicated in dysfunction of both salience network (SN) and default mode network (DMN) in PTSD sufferers. A literature search was conducted in Embase, Medline, PubMed and PsycINFO in May 2013. Fifty-nine volumetric analyses from 44 articles were examined and included (36 hippocampus, 14 amygdala and nine ACC) with n=846 PTSD participants, n=520 healthy controls (HCs) and n=624 traumatised controls (TCs). Nine statistical tests were performed for each of the three regions of interest (ROIs), measuring volume differences in PTSD subjects, healthy and traumatised controls. Hippocampal volume was reduced in subjects with PTSD, with a greater reduction in the left hippocampus. A medium effect size reduction was found in bilateral amygdala volume when compared with findings in healthy controls; however, no significant differences in amygdala volume between PTSD subjects and trauma-exposed controls were found. Significant volume reductions were found bilaterally in the ACC. While often well matched with their respective control groups, the samples of PTSD subjects composed from the source studies used in the meta-analyses are limited in their homogeneity. The current findings of reduced hippocampal volume in subjects with PTSD are consistent with the existing literature. Amygdala volumes did not show significant reductions in PTSD subjects when compared with volumes in trauma-exposed controls-congruous with reported symptoms of hypervigilance and increased propensity in acquisition of conditioned fear memories-but a significant reduction was found in the combined left and right hemisphere volume analysis when compared with healthy controls. Bilateral volume reductions in the ACC may underpin the attentional deficits and inabilities to modulate emotions that are characteristically associated with PTSD patients.
Topics: Amygdala; Fear; Gyrus Cinguli; Hippocampus; Humans; Magnetic Resonance Imaging; Stress Disorders, Post-Traumatic; Veterans
PubMed: 25735885
DOI: 10.1016/j.pscychresns.2015.01.002 -
Brain Imaging and Behavior Oct 2022Motor training is a widely used therapy in many pain conditions. The brain's capacity to undergo functional and structural changes i.e., neuroplasticity is fundamental... (Review)
Review
Motor training is a widely used therapy in many pain conditions. The brain's capacity to undergo functional and structural changes i.e., neuroplasticity is fundamental to training-induced motor improvement and can be assessed by transcranial magnetic stimulation (TMS). The aim was to investigate the impact of pain on training-induced motor performance and neuroplasticity assessed by TMS. The review was carried out in accordance with the PRISMA-guidelines and a Prospero protocol (CRD42020168487). An electronic search in PubMed, Web of Science and Cochrane until December 13, 2019, identified studies focused on training-induced neuroplasticity in the presence of experimentally-induced pain, 'acute pain' or in a chronic pain condition, 'chronic pain'. Included studies were assessed by two authors for methodological quality using the TMS Quality checklist, and for risk of bias using the Newcastle-Ottawa Scale. The literature search identified 231 studies. After removal of 71 duplicates, 160 abstracts were screened, and 24 articles were reviewed in full text. Of these, 17 studies on acute pain (n = 7) or chronic pain (n = 10), including a total of 258 patients with different pain conditions and 248 healthy participants met the inclusion criteria. The most common types of motor training were different finger tasks (n = 6). Motor training was associated with motor cortex functional neuroplasticity and six of seven acute pain studies and five of ten chronic pain studies showed that, compared to controls, pain can impede such trainings-induced neuroplasticity. These findings may have implications for motor learning and performance and with putative impact on rehabilitative procedures such as physiotherapy.
Topics: Humans; Magnetic Resonance Imaging; Neuronal Plasticity; Transcranial Magnetic Stimulation; Motor Cortex; Chronic Pain; Chronic Disease
PubMed: 35301674
DOI: 10.1007/s11682-021-00621-6 -
Neurology Apr 2013To compare standard anterior temporal lobectomy (ATL) with selective amygdalohippocampectomy (SAH) for postoperative seizure control in temporal lobe epilepsy (TLE). (Comparative Study)
Comparative Study Meta-Analysis Review
OBJECTIVE
To compare standard anterior temporal lobectomy (ATL) with selective amygdalohippocampectomy (SAH) for postoperative seizure control in temporal lobe epilepsy (TLE).
METHODS
We searched MEDLINE and Embase using Medical Subject Headings and keywords related to ATL and SAH. We included original research that directly compared seizure outcomes in patients undergoing SAH or ATL for TLE. A fixed-effect model was used to derive a pooled risk ratio (RR) for either an Engel Class I (free of disabling seizures) or a composite of an Engel Class I and II (rare disabling seizures) outcome.
RESULTS
Of 4,675 abstracts initially identified by the search, 65 were reviewed as full text. Thirteen studies containing data from 8 countries (5 continents) met our inclusion criteria. Eleven studies comprising 1,203 patients demonstrated that participants were statistically more likely to achieve an Engel Class I outcome after ATL compared with SAH (risk ratio 1.32, 95% confidence interval [CI] 1.12-1.57; p < 0.01). The summary risk difference of 8% (95% CI 3%-14%) translates to a number needed to treat of 13 (95% CI 7-33) for 1 additional patient to achieve an Engel Class I outcome after ATL. The result remained significant when 2 studies that contained fewer than 15 participants in at least 1 arm were excluded and in analyses restricted to hippocampal sclerosis.
CONCLUSIONS
Standard ATL confers an improved chance of achieving freedom from disabling seizures in patients with TLE. Improved seizure freedom must be balanced against the neuropsychological impact of each procedure. A randomized controlled trial is justified.
Topics: Amygdala; Anterior Temporal Lobectomy; Epilepsy, Temporal Lobe; Hippocampus; Humans; Remission Induction; Temporal Lobe
PubMed: 23553475
DOI: 10.1212/WNL.0b013e3182904f82 -
Brain Imaging and Behavior Oct 2021Knowing target regions undergoing strfuncti changes caused by behavioural interventions is paramount in evaluating the effectiveness of such practices. Here, using a... (Meta-Analysis)
Meta-Analysis Review
Knowing target regions undergoing strfuncti changes caused by behavioural interventions is paramount in evaluating the effectiveness of such practices. Here, using a systematic review approach, we identified 25 peer-reviewed magnetic resonance imaging (MRI) studies demonstrating grey matter changes related to mindfulness meditation. An activation likelihood estimation (ALE) analysis (n = 16) revealed the right anterior ventral insula as the only significant region with consistent effect across studies, whilst an additional functional connectivity analysis indicates that both left and right insulae, and the anterior cingulate gyrus with adjacent paracingulate gyri should also be considered in future studies. Statistical meta-analyses suggest medium to strong effect sizes from Cohen's d ~ 0.8 in the right insula to ~ 1 using maxima across the whole brain. The systematic review revealed design issues with selection, information, attrition and confirmation biases, in addition to weak statistical power. In conclusion, our analyses show that mindfulness meditation practice does induce grey matter changes but also that improvements in methodology are needed to establish mindfulness as a therapeutic intervention.
Topics: Brain; Cerebral Cortex; Gray Matter; Humans; Magnetic Resonance Imaging; Mindfulness
PubMed: 33624219
DOI: 10.1007/s11682-021-00453-4 -
Stereotactic and Functional Neurosurgery 2022Ablative lesion procedures remain as the last option in treatment of refractory depression. Contemporary ablative psychosurgeries involve producing lesions in the... (Meta-Analysis)
Meta-Analysis
BACKGROUND AND OBJECTIVES
Ablative lesion procedures remain as the last option in treatment of refractory depression. Contemporary ablative psychosurgeries involve producing lesions in the anterior limb of the internal capsule (bilateral anterior capsulotomy - BAC), the supragenual anterior cingulate gyrus and cingulum (bilateral anterior cingulotomy - BACING), and subgenual anterior cingulate gyrus and subcortical orbitofrontal white matter (bilateral subcaudate tractotomy - BST). A combination of BACING and BST is known as limbic leukotomy (bilateral limbic leukotomy - BLL). All procedures claim some success, but cohorts are small, depression assessment instruments differ, and inclusion and outcome criteria and follow-up duration vary. In some cohorts, more than one type of surgery was performed in several patients, further confounding interpreting the available data. Current evidence is equivocal on which surgical target works best. Method and Aim: This systematic review and meta-analysis using the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) standard on published cohorts was conducted to review and identify which is the best standalone ablative procedure for treatment-resistant depression (TRD) based on response rate (event rate) and adverse-effect profile using the Comprehensive Meta-Analysis software.
RESULTS AND CONCLUSION
As a standalone neurosurgical procedure, we found that BAC appears to be the most effective and safest of all the ablative targets for TRD. A major limitation of this conclusion is the paucity of published case series where sample sizes are small and all are open label.
Topics: Humans; Depression; Depressive Disorder, Treatment-Resistant; Psychosurgery; Neurosurgical Procedures; Gyrus Cinguli
PubMed: 35973404
DOI: 10.1159/000526000 -
NeuroImage. Clinical 2019To compare structure, functional connectivity (FC) and task-based neural differences in subjects with generalized anxiety disorder (GAD) compared to healthy controls... (Meta-Analysis)
Meta-Analysis
OBJECTIVE
To compare structure, functional connectivity (FC) and task-based neural differences in subjects with generalized anxiety disorder (GAD) compared to healthy controls (HC).
METHODS
The Embase, Ovid Medline, PsycINFO, Scopus, and Web of Science databases were searched from inception until March 12, 2018. Two reviewers independently screened titles, abstracts, and full-text articles. Data were extracted from records directly contrasting GAD and HC that included structure (connectivity and local indices such as volume, etc.), FC, or task-based magnetic resonance imaging data. Meta-analyses were conducted, as applicable, using AES-SDM software.
RESULTS
The literature search produced 4,645 total records, of which 85 met the inclusion criteria for the systematic review. Records included structural (n = 35), FC (n = 33), and task-based (n = 42) findings. Meta-analyses were conducted on voxel-based morphometry and task-based results.
DISCUSSION
The systematic review confirms and extends findings from previous reviews. Although few whole-brain resting state studies were conducted, key nodes of resting state networks have altered physiology: the hippocampus (default network), ACC and amygdala (salience network), have reduced volume, and the dlPFC (central executive network) and ACC have reduced FC with the amygdala in GAD. Nodes in the sensorimotor network are also altered with greater pre- and postcentral volume, reduced supplementary motor area volume, and reduced FC in anterior and increased FC in posterior cerebellum.
CONCLUSIONS
Despite limitations due to sample size, the meta-analyses highly agree with the systematic review and provide evidence of widely distributed neural differences in subjects with GAD, compared to HC. Further research optimized for meta-analyses would greatly improve large-scale comparisons.
Topics: Amygdala; Anxiety Disorders; Cerebral Cortex; Connectome; Humans; Magnetic Resonance Imaging; Nerve Net
PubMed: 31835287
DOI: 10.1016/j.nicl.2019.102016 -
Biology of Sex Differences 2017Gender-specific differences in hypothalamus-pituitary-adrenal (HPA) axis activity have been postulated to emerge during puberty. We conducted a systematic review and... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
Gender-specific differences in hypothalamus-pituitary-adrenal (HPA) axis activity have been postulated to emerge during puberty. We conducted a systematic review and meta-analysis to test the hypothesis that gender-specific differences in HPA axis activity are already present in childhood.
METHODS
From inception to January 2016, PubMed and EMBASE.com were searched for studies that assessed non-stimulated cortisol in serum or saliva or cortisol in 24-h urine in healthy males and females aged ≤18 years. Studies that conform with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) statement were reported. Standardized mean differences (95% CIs) were calculated and analyzed using fixed-effect meta-analysis stratified for age: <8 years (prepubertal) and 8-18 years (peri-/postpubertal). For comparison, we ran the same analyses using random-effects models.
RESULTS
Two independent assessors selected 413 out of 6158 records (7%) for full-text screening, of which 79 articles were included. Of these, 58 (with data on 16,551 subjects) were included in the meta-analysis. Gender differences in cortisol metabolism differed per age group. Boys aged <8 years had 0.18 (0.06; 0.30) nmol/L higher serum and 0.21 (0.05; 0.37) nmol/L higher salivary cortisol levels, while between 8 and 18 years, boys had 0.34 (0.28; 0.40) nmol/L lower serum and 0.42 (0.38; 0.47) nmol/L lower salivary cortisol levels. In 24-h urine, cortisol was consistently higher in boys, being 0.34 (0.05; 0.64) and 0.32 (0.17; 0.47) μg/24 h higher in the <8- and 8-18-year groups, respectively. However, gender-differences in serum cortisol <8 years and between 8 and 18 years were absent when using random-effects models.
CONCLUSIONS
Gender differences in cortisol metabolism are already present in childhood, with higher salivary cortisol in boys aged <8 years compared to girls. This pattern was reversed after the age of 8 years. In contrast, the gender-specific difference in cortisol production as assessed through 24-h urine did not change with age. Although differences were small, and analyses of gender differences in serum cortisol were inconclusive, they might contribute to gender-specific origins of health and disease.
Topics: Child; Humans; Hypothalamo-Hypophyseal System; Pituitary-Adrenal System; Sex Characteristics
PubMed: 28116043
DOI: 10.1186/s13293-016-0123-5