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Journal of Affective Disorders Jun 2024We conducted a meta-analysis and qualitative review on the randomized controlled trials investigating the effects of transcranial direct current stimulation and... (Review)
Review
BACKGROUND
We conducted a meta-analysis and qualitative review on the randomized controlled trials investigating the effects of transcranial direct current stimulation and transcranial magnetic stimulation on fear extinction and the return of fear in non-primate animals and humans.
METHODS
The meta-analysis was conducted by searching PubMed, Web of science, PsycINFO, and Cochrane Library and extracting fear response in the active and sham groups in the randomized controlled trials. The pooled effect size was quantified by Hedges' g using a three-level meta-analytic model in R.
RESULTS
We identified 18 articles on the tDCS effect and 5 articles on the TMS effect, with 466 animal subjects and 621 human subjects. Our findings show that tDCS of the prefrontal cortex significantly inhibit fear retrieval in animal models (Hedges' g = -0.50). In human studies, TMS targeting the dorsolateral/ventromedial prefrontal cortex has an inhibiting effect on the return of fear (Hedges' g = -0.24).
LIMITATIONS
The limited number of studies and the heterogeneous designs of the selected studies made cross-study and cross-species comparison difficult.
CONCLUSIONS
Our findings shed light on the optimal non-invasive brain stimulation protocols for targeting the neural circuitry of threat extinction in humans.
PubMed: 38908557
DOI: 10.1016/j.jad.2024.06.060 -
The Australian and New Zealand Journal... May 2024Studies using proton magnetic resonance spectroscopy reveal substantial inconsistencies in the levels of brain glutamate, glutamine and glutamate + glutamine across... (Review)
Review
Glutamatergic neurotransmission in schizophrenia: A systematic review and quantitative synthesis of proton magnetic resonance spectroscopy studies across schizophrenia spectrum disorders.
OBJECTIVE
Studies using proton magnetic resonance spectroscopy reveal substantial inconsistencies in the levels of brain glutamate, glutamine and glutamate + glutamine across schizophrenia spectrum disorders. This systematic review employs qualitative and quantitative methods to analyse the patterns and relationships between glutamatergic metabolites, schizophrenia spectrum disorders and brain regions.
METHODS
A literature search was conducted using various databases with keywords including glutamate, glutamine, schizophrenia, psychosis and proton magnetic resonance spectroscopy. Inclusion criteria were limited to case-control studies that reported glutamatergic metabolite levels in adult patients with a schizophrenia spectrum disorder diagnosis - i.e. first-episode psychosis, schizophrenia, treatment-resistant schizophrenia and/or ultra-treatment-resistant schizophrenia - using proton magnetic resonance spectroscopy at 3 T or above. Pooled study data were synthesized and analysed.
RESULTS
A total of 92 studies met the inclusion criteria, including 2721 healthy controls and 2822 schizophrenia spectrum disorder participants. Glu levels were higher in the basal ganglia, frontal cortex and medial prefrontal of first-episode psychosis participants, contrasting overall lower levels in schizophrenia participants. For Gln, strong differences in metabolite levels were evident in the basal ganglia, dorsolateral prefrontal cortex and frontal cortex, with first-episode psychosis showing significantly higher levels in the basal ganglia. In glutamate + glutamine, higher metabolite levels were found across schizophrenia spectrum disorder groups, particularly in the basal ganglia and dorsolateral prefrontal cortex of treatment-resistant schizophrenia participants. Significant relationships were found between metabolite levels and medication status, clinical measures and methodological variables.
CONCLUSION
The review highlights abnormal glutamatergic metabolite levels throughout schizophrenia spectrum disorders and in specific brain regions. The review underscores the importance of standardized future research assessing glutamatergic metabolites using proton magnetic resonance spectroscopy due to considerable literature heterogeneity.
PubMed: 38812258
DOI: 10.1177/00048674241254216 -
JAMA Network Open May 2024Noninvasive brain stimulation (NIBS) interventions have been shown to be efficacious in several mental disorders, but the optimal dose stimulation parameters for each... (Meta-Analysis)
Meta-Analysis
IMPORTANCE
Noninvasive brain stimulation (NIBS) interventions have been shown to be efficacious in several mental disorders, but the optimal dose stimulation parameters for each disorder are unknown.
OBJECTIVE
To define NIBS dose stimulation parameters associated with the greatest efficacy in symptom improvement across mental disorders.
DATA SOURCES
Studies were drawn from an updated (to April 30, 2023) previous systematic review based on a search of PubMed, OVID, and Web of Knowledge.
STUDY SELECTION
Randomized clinical trials were selected that tested transcranial magnetic stimulation (TMS) or transcranial direct current stimulation (tDCS) for any mental disorder in adults aged 18 years or older.
DATA EXTRACTION AND SYNTHESIS
Two authors independently extracted the data. A 1-stage dose-response meta-analysis using a random-effects model was performed. Sensitivity analyses were conducted to test robustness of the findings. This study followed the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) reporting guideline.
MAIN OUTCOMES AND MEASURES
The main outcome was the near-maximal effective doses of total pulses received for TMS and total current dose in coulombs for tDCS.
RESULTS
A total of 110 studies with 4820 participants (2659 men [61.4%]; mean [SD] age, 42.3 [8.8] years) were included. The following significant dose-response associations emerged with bell-shaped curves: (1) in schizophrenia, high-frequency (HF) TMS on the left dorsolateral prefrontal cortex (LDLPFC) for negative symptoms (χ2 = 9.35; df = 2; P = .009) and TMS on the left temporoparietal junction for resistant hallucinations (χ2 = 36.52; df = 2; P < .001); (2) in depression, HF-DLPFC TMS (χ2 = 14.49; df = 2; P < .001); (3) in treatment-resistant depression, LDLPFC tDCS (χ2 = 14.56; df = 2; P < .001); and (4) in substance use disorder, LDLPFC tDCS (χ2 = 33.63; df = 2; P < .001). The following significant dose-response associations emerged with plateaued or ascending curves: (1) in depression, low-frequency (LF) TMS on the right DLPFC (RDLPFC) with ascending curve (χ2 = 25.67; df = 2; P = .001); (2) for treatment-resistant depression, LF TMS on the bilateral DLPFC with ascending curve (χ2 = 5.86; df = 2; P = .004); (3) in obsessive-compulsive disorder, LF-RDLPFC TMS with ascending curve (χ2 = 20.65; df = 2; P < .001) and LF TMS on the orbitofrontal cortex with a plateaued curve (χ2 = 15.19; df = 2; P < .001); and (4) in posttraumatic stress disorder, LF-RDLPFC TMS with ascending curve (χ2 = 54.15; df = 2; P < .001). Sensitivity analyses confirmed the main findings.
CONCLUSIONS AND RELEVANCE
The study findings suggest that NIBS yields specific outcomes based on dose parameters across various mental disorders and brain regions. Clinicians should consider these dose parameters when prescribing NIBS. Additional research is needed to prospectively validate the findings in randomized, sham-controlled trials and explore how other parameters contribute to the observed dose-response association.
Topics: Humans; Transcranial Magnetic Stimulation; Transcranial Direct Current Stimulation; Mental Disorders; Adult; Male; Female; Middle Aged; Randomized Controlled Trials as Topic
PubMed: 38776083
DOI: 10.1001/jamanetworkopen.2024.12616 -
Neuroscience and Biobehavioral Reviews Jul 2024This review synthesises individual differences in neural processes related to emotion regulation (ER). It comprises individual differences in self-reported and... (Review)
Review
This review synthesises individual differences in neural processes related to emotion regulation (ER). It comprises individual differences in self-reported and physiological regulation success, self-reported ER-related traits, and demographic variables, to assess their correlation with brain activation during ER tasks. Considering region-of-interest (ROI) and whole-brain analyses, the review incorporated data from 52 functional magnetic resonance imaging studies. Results can be summarized as follows: (1) Self-reported regulation success (assessed by emotional state ratings after regulation) and self-reported ER-related traits (assessed by questionnaires) correlated with brain activity in the lateral prefrontal cortex. (2) Amygdala activation correlated with ER-related traits only in ROI analyses, while it was associated with regulation success in whole-brain analyses. (3) For demographic and physiological measures, there was no systematic overlap in effects reported across studies. In showing that individual differences in regulation success and ER-related traits can be traced back to differences in the neural activity of brain regions associated with emotional reactivity (amygdala) and cognitive control (lateral prefrontal cortex), our findings can inform prospective personalised intervention models.
Topics: Humans; Individuality; Emotional Regulation; Brain; Magnetic Resonance Imaging; Amygdala; Emotions; Brain Mapping; Prefrontal Cortex
PubMed: 38759742
DOI: 10.1016/j.neubiorev.2024.105727 -
International Journal of Bipolar... May 2024Bipolar disorder (BD) is a severe psychiatric disorder characterized by changes in mood that alternate between (hypo) mania or depression and mixed states, often...
BACKGROUND
Bipolar disorder (BD) is a severe psychiatric disorder characterized by changes in mood that alternate between (hypo) mania or depression and mixed states, often associated with functional impairment and cognitive dysfunction. But little is known about biomarkers that contribute to the development and sustainment of cognitive deficits. The aim of this study was to review the association between neurocognition and biomarkers across different mood states.
METHOD
Search databases were Web of Science, Scopus and PubMed. A systematic review was carried out following the PRISMA guidelines. Risk of bias was assessed with the Newcastle-Ottawa Scale. Studies were selected that focused on the correlation between neuroimaging, physiological, genetic or peripheral biomarkers and cognition in at least two phases of BD: depression, (hypo)mania, euthymia or mixed. PROSPERO Registration No.: CRD42023410782.
RESULTS
A total of 1824 references were screened, identifying 1023 published articles, of which 336 were considered eligible. Only 16 provided information on the association between biomarkers and cognition in the different affective states of BD. The included studies found: (i) Differences in levels of total cholesterol and C reactive protein depending on mood state; (ii) There is no association found between cognition and peripheral biomarkers; (iii) Neuroimaging biomarkers highlighted hypoactivation of frontal areas as distinctive of acute state of BD; (iv) A deactivation failure has been reported in the ventromedial prefrontal cortex (vmPFC), potentially serving as a trait marker of BD.
CONCLUSION
Only a few recent articles have investigated biomarker-cognition associations in BD mood phases. Our findings underline that there appear to be central regions involved in BD that are observed in all mood states. However, there appear to be underlying mechanisms of cognitive dysfunction that may vary across different mood states in BD. This review highlights the importance of standardizing the data and the assessment of cognition, as well as the need for biomarkers to help prevent acute symptomatic phases of the disease, and the associated functional and cognitive impairment.
PubMed: 38758506
DOI: 10.1186/s40345-024-00340-z -
Neuroscience and Biobehavioral Reviews Jul 2024There is a lack of consensus on anatomical nomenclature, standards of documentation, and functional equivalence of the frontal cortex between species. There remains a... (Review)
Review
There is a lack of consensus on anatomical nomenclature, standards of documentation, and functional equivalence of the frontal cortex between species. There remains a major gap between human prefrontal function and interpretation of findings in the mouse brain that appears to lack several key prefrontal areas involved in cognition and psychiatric illnesses. The ferret is an emerging model organism that has gained traction as an intermediate model species for the study of top-down cognitive control and other higher-order brain functions. However, this research has yet to benefit from synthesis. Here, we provide a summary of all published research pertaining to the frontal and/or prefrontal cortex of the ferret across research scales. The targeted location within the ferret brain is summarized visually for each experiment, and the anatomical terminology used at time of publishing is compared to what would be the appropriate term to use presently. By doing so, we hope to improve clarity in the interpretation of both previous and future publications on the comparative study of frontal cortex.
Topics: Prefrontal Cortex; Animals; Ferrets; Models, Animal; Humans
PubMed: 38718987
DOI: 10.1016/j.neubiorev.2024.105701 -
Brain Sciences Mar 2024Craving is one of the most important symptoms of cocaine use disorder (CUD) since it contributes to the relapse and persistence of such disorder. This systematic review... (Review)
Review
Craving is one of the most important symptoms of cocaine use disorder (CUD) since it contributes to the relapse and persistence of such disorder. This systematic review aimed to investigate which brain regions are modulated during cocaine craving. The articles were obtained through searches in the Google Scholar, Regional BVS Portal, PubMed, and Scielo databases. Overall, there was a selection of 36 studies with 1574 individuals, the majority being participants with CUD, whereby about 61.56% were individuals with CUD and 38.44% were controls (mean age = 40.4 years). Besides the methodological points, the neurobiological investigations comprised fMRI (58.34%) and PET (38.89%). The induction of cocaine craving was studied using different methods: exposure to cocaine cues (69.45%), stressful stimuli, food cues, and methylphenidate. Brain activations demonstrated widespread activity across the frontal, parietal, temporal, and occipital lobes, basal ganglia, diencephalon, brainstem, and the limbic system. In addition to abnormalities in prefrontal cortex activity, abnormalities in various other brain regions' activity contribute to the elucidation of the neurobiology of cocaine craving. Abnormalities in brain activity are justified not only by the dysfunction of dopaminergic pathways but also of the glutamatergic and noradrenergic pathways, and distinct ways of inducing craving demonstrated the involvement of distinct brain circuits and regions.
PubMed: 38671981
DOI: 10.3390/brainsci14040329 -
Psychoradiology 2023Loneliness is associated with high prevalences of major psychiatric illnesses such as major depression. However, the underlying emotional mechanisms of loneliness... (Review)
Review
Loneliness is associated with high prevalences of major psychiatric illnesses such as major depression. However, the underlying emotional mechanisms of loneliness remained unclear. We hypothesized that loneliness originates from both decreases in positive emotional processing and increases in negative emotion processing. To test this, we conducted a systematic review of 29 previous studies (total participants = 19 560, mean age = 37.16 years, female proportion = 59.7%), including 18 studies that included questionnaire measures of emotions only, and 11 studies that examined the brain correlates of emotions. The main findings were that loneliness was negatively correlated with general positive emotions and positively correlated with general negative emotions. Furthermore, limited evidence indicates loneliness exhibited negative and positive correlations with the brain positive (e.g. the striatum) and negative (e.g. insula) emotion systems, respectively, but the sign of correlation was not entirely consistent. Additionally, loneliness was associated with the structure and function of the brain emotion regulation systems, particularly the prefrontal cortex, but the direction of this relationship remained ambiguous. We concluded that the existing evidence supported a bivalence model of loneliness, but several critical gaps existed that could be addressed by future studies that include adolescent and middle-aged samples, use both questionnaire and task measures of emotions, distinguish between general emotion and social emotion as well as between positive and negative emotion regulation, and adopt a longitudinal design that allows us to ascertain the causal relationships between loneliness and emotion dysfunction. Our findings provide new insights into the underlying emotion mechanisms of loneliness that can inform interventions for lonely individuals.
PubMed: 38666115
DOI: 10.1093/psyrad/kkad029 -
Frontiers in Psychology 2024Exercise can induce brain plasticity. Functional near-infrared spectroscopy (fNIRS) is a functional neuroimaging technique that exploits cerebral hemodynamics and has...
Exercise can induce brain plasticity. Functional near-infrared spectroscopy (fNIRS) is a functional neuroimaging technique that exploits cerebral hemodynamics and has been widely used in the field of sports psychology to reveal the neural mechanisms underlying the effects of exercise. However, most existing fNIRS studies are cross-sectional and do not include exercise interventions. In addition, attributed to differences in experimental designs, the causal relationship between exercise and brain functions remains elusive. Hence, this systematic review aimed to determine the effects of exercise interventions on alterations in brain functional activity in healthy individuals using fNIRS and to determine the applicability of fNIRS in the research design of the effects of various exercise interventions on brain function. Scopus, Web of Science, PubMed, CNKI, Wanfang, and Weipu databases were searched for studies published up to June 15, 2021. This study was performed in accordance with the PRISMA guidelines. Two investigators independently selected articles and extracted relevant information. Disagreements were resolved by discussion with another author. Quality was assessed using the Cochrane risk-of-bias method. Data were pooled using random-effects models. A total of 29 studies were included in the analysis. Our results indicated that exercise interventions alter oxygenated hemoglobin levels in the prefrontal cortex and motor cortex, which are associated with improvements in higher cognitive functions (e.g., inhibitory control and working memory). The frontal cortex and motor cortex may be key regions for exercise-induced promotion of brain health. Future research is warranted on fluctuations in cerebral blood flow during exercise to elucidate the neural mechanism underlying the effects of exercise. Moreover, given that fNIRS is insensitive to motion, this technique is ideally suited for research during exercise interventions. Important factors include the study design, fNIRS device parameters, and exercise protocol. The examination of cerebral blood flow during exercise intervention is a future research direction that has the potential to identify cortical hemodynamic changes and elucidate the relationship between exercise and cognition. Future studies can combine multiple study designs to measure blood flow prior to and after exercise and during exercise in a more in-depth and comprehensive manner.
PubMed: 38659667
DOI: 10.3389/fpsyg.2024.1327822 -
Frontiers in Aging Neuroscience 2024With aging, dual task (DT) ability declines and is more cognitively demanding than single tasks. Rapidly declining DT performance is regarded as a predictor of...
INTRODUCTION
With aging, dual task (DT) ability declines and is more cognitively demanding than single tasks. Rapidly declining DT performance is regarded as a predictor of neurodegenerative disease. Task training and non-invasive transcranial electrical stimulation (tES) are methods applied to optimize the DT ability of the elderly.
METHODS
A systematic search was carried out in the PUBMED, TDCS (transcranial direct current stimulation) databases, as well as Web of Science, and a qualitative analysis was conducted in 56 included studies. Aiming to summarize the results of studies that implemented tES, task training, or the combination for improving DT ability and related performance changes in healthy elderly and geriatric patients. For different approaches, the training procedures, parameters, as well as outcomes were discussed.
RESULTS
Task training, particularly cognitive-motor DT training, has more notable effects on improving DT performance in the elderly when compared to the neuromodulation method.
DISCUSSION
Anodal transcranial direct current stimulation (tDCS) over the left dorsolateral prefrontal cortex (L-DLPFC), or its combination with task training could be promising tools. However, additional evidence is required from aged healthy people and patients, as well as further exploration of electrode montage.
PubMed: 38650865
DOI: 10.3389/fnagi.2024.1267307