Repetitive transcranial magnetic stimulation in Alzheimer’s disease:effects on neural and synaptic rehabilitation

Alzheimer’s disease is a neurodegenerative disease resulting from deficits in synaptic transmission and homeostasis.The Alzheimer’s disease brain tends to be hyperexcitable and hypersynchronized,thereby causing neurodegeneration and ultimately disrupting the operational abilities in daily life,leaving patients incapacitated.Repetitive transcranial magnetic stimulation is a cost-effective,neuro-modulatory technique used for multiple neurological conditions.Over the past two decades,it has been widely used to predict cognitive decline;identify pathophysiological markers;promote neuroplasticity;and assess brain excitability,plasticity,and connectivity.It has also been applied to patients with dementia,because it can yield facilitatory effects on cognition and promote brain recovery after a neurological insult.However,its therapeutic effectiveness at the molecular and synaptic levels has not been elucidated because of a limited number of studies.This study aimed to characterize the neurobiological changes following repetitive transcranial magnetic stimulation treatment,evaluate its effects on synaptic plasticity,and identify the associated mechanisms.This review essentially focuses on changes in the pathology,amyloidogenesis,and clearance pathways,given that amyloid deposition is a major hypothesis in the pathogenesis of Alzheimer’s disease.Apoptotic mechanisms associated with repetitive transcranial magnetic stimulation procedures and different pathways mediating gene transcription,which are closely related to the neural regeneration process,are also highlighted.Finally,we discuss the outcomes of animal studies in which neuroplasticity is modulated and assessed at the structural and functional levels by using repetitive transcranial magnetic stimulation,with the aim to highlight future directions for better clinical translations.

MicroRNA-451a is a candidate biomarker and therapeutic target for major depressive disorder

Background Increasing evidence supports the role of microRNAs(miRNAs)in major depressive disorder(MDD),but the pathophysiological mechanism remains elusive.Aims To explore the mechanism of microRNA-451a(miR-451a)in the pathology and behaviours of depression.Methods Abnormal miRNAs such as miR-451a reported previously in the serum of patients with MDD were screened and then confirmed in a mouse model of depression induced by chronic restraint stress(CRS).Eight-week-old male C57BL/6 mice had miR-451a overexpression in the medial prefrontal cortex(mPFC)via adeno-associated virus serotype 9 vectors encoding a pri-mmu-miR-451a-GFP fusion protein followed by behavioural and pathological analyses.Finally,molecular biological experiments were conducted to investigate the potential mechanism of miR-451a against depression.Results The serum levels of miRNA-451awere significantly lower in patients with MDD,with a negative correlation with the Hamilton Depression Scale scores.Additionally,a negative association between serum miR-451a and behavioural despair or anhedonia was observed in CRS mice.Notably,miR-451a expression was significantly downregulated in the mPFC of CRS-susceptible mice.Overexpressing miR-451a in the mPFC reversed the loss of dendritic spines and the depression-like phenotype of CRS mice.Mechanistically,miR-451a could inhibit CRS-induced corticotropin-releasing factor receptor 1 expression via targeting transcription factor 2,subsequently protecting dendritic spine plasticity.Conclusions Together,these results highlighted miR-451a as a candidate biomarker and therapeutic target for MDD.

Effects of a periodic intermittent theta burst stimulation in Alzheimer's disease

Background Previous studies havedemonstrated that excitatory repetitive transcranial magnetic stimulation(rTMS)can improve the cognitive function of patients with Alzheimer's disease(AD).Intermittent theta burst stimulation(iTBS)is a novel excitatory rTMS protocol for brain activity stimulation with the ability to induce long-term potentiation-like plasticity and represents a promising treatment for AD.However,the long-term effects of iTBS on cognitive decline and brain structure in patients with AD areunknown.Aims We aimed to explore whether repeating accelerated iTBS every three months could slow down the cognitive decline in patients with AD.Methods In this randomised,assessor-blinded,controlled trial,iTBS was administered to the left dorsolateral prefrontal cortex(DLPFC)of 42 patients with AD for 14days every 13weeks.Measurements included the Montreal Cognitive Assessment(MoCA),a comprehensive neuropsychological battery,and the grey matter volume(GMV)of the hippocampus.Patients were evaluated at baseline and after follow-up.The longitudinal pipeline of the Computational Anatomy Toolbox for SPM was used to detect significant treatment-related changes over time.Results The iTBS group maintained MoCA scores relative to the control group(t=3.26,p=0.013)and reduced hippocampal atrophy,which was significantly correlated with global degeneration scale changes.The baseline Mini-Mental State Examination(MMSE)score,apolipoprotein E genotype and Clinical Dementia Rating were indicative of MoCA scores at follow-up.Moreover,the GMV of the left(t=0.08,p=0.996)and right(t=0.19,p=0.977)hippocampus were maintained in the active group but significantly declined in the control group(left:t=4.13,p<0.001;right:t=5.31,p<0.001).GMV change in the left(r=0.35,p=0.023)and right(r=0.36,p=0.021)hippocampus across the intervention positively correlated with MoCA changes;left hippocampal GMV change was negatively correlated with global degeneration scale(r=-0.32,p=0.041)changes.Conclusions DLPFC-iTBS maybe a feasible and easy-to-implement non-pharmacological intervention to slow down the progressive decline of overall cognition and quality of life in patients with AD,providing a new AD treatment option.Trial registration number NCT04754152.

Microtopographic modification conserves urban wetland water quality by increasing the dissolved oxygen in the wet season

Microtopography affects hydrological processes and forms different microhabitats.Our previous study uncovered that riparian zone microtopography created various microhabitats with different soil environments and runoff-infiltration patterns.However,how riparian microtopography and microtopography within the water area(waterfall and tributary)affects downstream water quality remains unclear.Therefore,water samples were taken almost monthly in both the main stream and the tributary,before and after waterfalls,and near the bottom of three microtopographic types from June 2016 to March 2017.Compared with the dry season,the fact that water quality worsened in the wet season and that there were positive correlations for nitrate(NO3-)between water and the corresponding soil samples suggested that the riparian-soil environment affected the adjacent water quality mainly in the wet season.Nevertheless,riparian microtopography did not influence water quality downstream because of the low rainfall frequency and the weak leaching process due to plant interception.In the wet season,both the tributary and the waterfall increased the dissolved oxygen in the water body and,therefore,lowered the risk of eutrophication.The tributary has two pathways for improving the water quality,by increased disturbance and flow velocity,while the waterfall only has the former.However,such effects were not significant in the dry season.We conclude that the application of microtopographic modification is useful in maintaining urban wetland water quality in wet seasons.