Meina Quan

• MD, PhD
• Research Scientist at Xuanwu Hospital, Capital Medical University

Glutamatergic processes are strongly implicated in the pathophysiology and treatment of depression, including the antidepressant effects of N-methyl-D-aspartate (NMDA) receptor antagonists. This study was designed to see whether memantine, a noncompetitive NMDA antagonist, has antidepressant effects in behaviors and synaptic plasticity. Rats were r...

Post weaning isolation-reared rats show deficits in learning and memory, which are also seen in many psychiatric disorders like schizophrenia. The present study utilized behavioral and electrophysiological tests to further characterize cognitive disorders in this rat model, and to explore possible neurobiological mechanisms associated with them. Is...

Background Metabolic syndrome (MetS) was associated with an increased incidence of mild cognitive impairment (MCI) and progression to dementia. Objective To study the associations between MetS indicators and cerebrospinal fluid (CSF) biomarkers in the participants. Methods 61 normal cognition, 66 mild MCI, and 135 dementia participants were inclu...

Background Alzheimer's disease (AD) is a common neurodegenerative disorder with a substantial genetic component. Despite advances in elucidating the genetic underpinnings of AD, much of its heritability remains unexplained. Discovering novel genetic variants and understanding their pathogenic roles are crucial challenges in AD research. Objective...

Background Metabolic syndrome (MetS) was associated with an increased incidence of mild cognitive impairment (MCI) and progression to dementia. However, little is known about why this occurs. This study was to examine the correlation between the MetS indicators and cerebrospinal fluid (CSF) pathological protein biomarkers to investigate this mechan...

Aims To analyze the effect of APOE ε4 on fluid biomarkers and the correlations between blood molecules and CSF biomarkers in AD patients. Methods This study enrolled 575 AD patients, 131 patients with non‐AD dementia, and 112 cognitively normal (CN) participants, and AD patients were divided into APOE ε4 carriers and non‐carriers. Cerebrospinal fl...

Alzheimer's disease is a common neurodegenerative disorder defined by decreased reasoning abilities, memory loss, and cognitive deterioration. The presence of the blood–brain barrier presents a major obstacle to the development of effective drug therapies for Alzheimer's disease. The use of ultrasound as a novel physical modulation approach has gar...

Alzheimer's disease (AD) is the leading cause of dementia, characterized by neuropathological features such as amyloid-β (Aβ) plaques, neurofibrillary tau tangles, and neurodegeneration. Immunotherapy offers a promising potentially disease-modifying treatment for AD. We review recent advances in AD immunotherapy, specifically focusing on Aβ, tau, a...

Background Neuropsychology and imaging changes have been reported in the preclinical stage of familial Alzheimer’s disease (FAD). This study investigated the effects of APOEε4 and known pathogenic gene mutation on different cognitive domains and circuit imaging markers in preclinical FAD. Method 139 asymptomatic subjects in FAD families, including...

Background Alzheimer disease (AD) is the most common neurodegenerative disorder leading to dementia in the elderly worldwide. Wnt signaling participates in multiple aspects of cellular function, and contributes to synapse formation, synaptic activity and neurogenesis in the brain, and dysfunction of Wnt signaling may aggravate the pathogenesis and...

Innovation Center of Neurological Disorders (ICND) at Xuanwu Hospital, Capital Medical University in Beijing was found in 2015 by Prof. Jianping Jia. The center follows the integrated research paradigm, called “cognitive unit”, which includes memory clinics, laboratories, and research wards. This unit facilitates the comprehensive diagnosis and tre...

Background: Multiple system atrophy (MSA) is a neurodegenerative disorder characterized by autonomic failure and motor dysfunction in parkinsonism and/or cerebellar ataxia. Patients with MSA usually present with depression and anxiety symptoms. This observational study of patients with MSA-cerebellar subtype (MSA-C) with subthreshold depression/...

Transgenic models are useful tools for studying the pathogenesis of and drug development for Alzheimer's Disease (AD). AD models are constructed usually using overexpression or knock-in of multiple pathogenic gene mutations from familial AD. Each transgenic model has its unique behavioral and pathological features. This review summarizes the resear...

Post-COVID cognitive dysfunction (PCCD) is a condition in which patients with a history of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, usually three months from the onset, exhibit subsequent cognitive impairment in various cognitive domains, and cannot be explained by an alternative diagnosis. While our knowledge of the...

Post-COVID cognitive dysfunction (PCCD) is a condition in which patients with a history of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, usually three months from the onset, exhibit subsequent cognitive impairment in various cognitive domains, and cannot be explained by an alternative diagnosis. While our knowledge of the...

Years of intensive research has brought us extensive knowledge on the genetic and molecular factors involved in Alzheimer's disease (AD). In addition to the mutations in the three main causative genes of familial AD (FAD) including presenilins and amyloid precursor protein genes, studies have identified several genes as the most plausible genes for...

Background: Neuropsychology and imaging changes have been reported in the preclinical stage of familial Alzheimer's disease (FAD). This study investigated the effects of APOEε4 and known pathogenic gene mutation on different cognitive domains and circuit imaging markers in preclinical FAD. Methods: One hundred thirty-nine asymptomatic subjects i...

Aims This study investigated the relationship between plasma Wnt2b levels and Alzheimer's disease (AD), and explored the effect of Wnt2b on mitochondrial dysfunction in AD. Methods Healthy and AD subjects, AD transgenic mice, and in vitro models were used to investigate the roles of Wnt2b in abnormalities in canonical Wnt signaling and mitochondri...

Background Although elevated levels of homocysteine (Hcy) are associated with cognitive impairment and dementia, the relevance of Hcy, vitamin B12, and folate levels to subtypes of dementia are still unknown. Objective To investigate the changes of Hcy, vitamin B12, and folate levels in mild cognitive impairment (MCI) and subtypes of dementia incl...

Background Most of the FDA approved drugs for AD are symptom driven and effects are limited. Because AD is a complex disease involving multiple pathological changes, such as senile plaques formed by amyloid‐β (Aβ) deposition, neurofibrillary tangles caused by tau hyperphosphorylation, microglia‐evoked neuroinflammation, synaptic degeneration, and b...

Background Transgenic mouse models are important tools for studying the pathogenesis of Alzheimer’s Disease (AD) and drug development. Commonly used models are constructed from early‐onset AD mutations in the Caucasian population, and are usually overexpression or knock‐in of multiple pathogenic gene mutations. However, they are not consistent with...

Alzheimer’s disease (AD) is the most common form of neurodegenerative disease and most anti-AD drugs have failed in clinical trials; hence, it is urgent to find potentially effective drugs against AD. DL-3-n-butylphthalide (NBP) is a compound extracted from celery seed and is a multiple-target drug. Several studies have demonstrated the neuroprotec...

Background Progressive multifocal leukoencephalopathy (PML) is a rare demyelinating lytic brain infection caused by the John Cunningham virus (JCV). JCV manifests primarily in patients with innate immunodeficiency or taking immunomodulatory medications. In this case study, we report a PML patient with comorbid mediastinal teratoma and mild lymphope...

Background China has the largest population of patients with dementia and mild cognitive impairment (MCI) in the world, imposing a heavy burden on the public and healthcare systems. The major concerns from the public health perspective include: prevalence, health economic burden, risk factors, and management strategy. Method Statistical analyses w...

Background In the preclinical stage of familial Alzheimer's disease (FAD), there have been changes in multi‐dimensional indicators, such as pathology, neuropsychology and imaging. This study explored the effects of known pathogenic gene mutation and ApoE on neuropsychology and imaging markers before the appearance of FAD symptoms. Method 102 cases...

Background Accelerated long-term forgetting has been identified in preclinical Alzheimer’s disease (AD) and is attributed to a selective impairment of memory consolidation in which the hippocampus plays a key role. As blood may contain multiple senescence-related factors that involved in neurogenesis and synaptic plasticity in the hippocampus, we t...

Background Gut microbiota can influence human brain function and behavior. Recent studies showed that gut microbiota might play an important role in the pathogenesis of Alzheimer’s disease (AD). Objective To investigate the composition of gut microbiota in AD patients and their association with cognitive function and neuropsychiatric symptoms (NPS...

Alzheimer’s disease (AD) research is entering a unique moment in which enormous information about the molecular basis of this disease is being translated into therapeutics. However, almost all drug candidates have failed in clinical trials over the past 30 years. These many trial failures have highlighted a need for the incorporation of biomarkers...

Background: Accelerated long-term forgetting has been identified in preclinical Alzheimer’s disease (AD), and is attributed to a selective impairment of memory consolidation in which hippocampus plays a key role. As blood may contain multiple senescence-related factors that involved in neurogenesis and synaptic plasticity in the hippocampus, we tes...

Background China has a large population of older people, but has not yet undertaken a comprehensive study on the prevalence, risk factors, and management of both dementia and mild cognitive impairment (MCI). Methods For this national cross-sectional study, 46 011 adults aged 60 years or older were recruited between March 10, 2015, and Dec 26, 2018...

Background Depression is one of the most common behavioral and psychological symptoms in people with Alzheimer’s disease (AD). To date, however, the molecular mechanisms underlying the clinical association between depression and AD remained elusive. Objective Here, we study the relationship between memory impairment and depressive-like behavior in...

Background: Although structural and functional changes of the striatum and hippocampus are present in familial Alzheimer's disease, little is known about the effects of specific gene mutation or disease progression on their related neural circuits. This study was to evaluate the effects of known pathogenic gene mutation and disease progression on...

Background The default mode network (DMN) could be divided into subsystems, the functional connectivity of which are different across the Alzheimer’s disease (AD) spectrum. However, the functional connectivity patterns within the subsystems are unknown in presymptomatic autosomal dominant AD (ADAD). Objective To investigate functional connectivity...

China has the largest population of patients with dementia in the world, imposing a heavy burden on the public and health care systems. More than 100 epidemiological studies on dementia have been done in China, but the estimates of the prevalence and incidence remain inconsistent because of the use of different sampling methods. Despite improved ac...

Abstract Background: Although structural and functional changes of the striatum and hippocampus are present in familial Alzheimer’s disease, little is known about the effects of specific gene mutation or disease progression on their related neural circuits. This study was to evaluate the effects of known pathogenic gene mutation and disease progres...

Presenilin 1 (PSEN1), presenilin 2 (PSEN2), and amyloid precursor protein (APP) genes account for the majority of autosomal dominant Alzheimer's disease (AD), with PSEN1 being the most common. We screened these genes for mutations in a Chinese proband from an autosomal dominant early-onset AD pedigree. Early-onset AD is defined as the age at onset...

Background: Soluble amyloid-β oligomer (AβO) induced deleterious cascades have recently been considered to be the initiating pathologic agents of Alzheimer's disease (AD). However, little is known about the neurotoxicity and production of different AβOs. Understanding the production and spread of toxic AβOs within the brain is important to improvi...

Background This study was to examine the insular cortical functional connectivity in drug naïve patients with first episode schizophrenia and to explore the relationship between the connectivity and the severity of clinical symptoms. Methods Thirty-seven drug naïve patients with schizophrenia and 25 healthy controls were enrolled in this study. A...

Introduction: Behavioral studies in chronic marijuana (MJ) smokers demonstrate that MJ smoking alters performance during cognitive tasks. Differences between chronic MJ smokers and non-smokers in brain activation during cognitive tasks have also been reported in frontal-limbic regions. We used the Multi Source Interference Test (MSIT), a measure of...

Background: Behavioral and imaging studies have suggested sex differences in cannabis use disorders. Specifically, women with cannabis dependence (CD) have more mood disorders, and have shown larger amygdala volume, a brain region involved in emotion processing. In contrast, men with CD have more comorbidity of other psychiatric and substance use d...

Background and Aims—Growing evidence suggests abnormalities in brain morphology including hippocampal structure in patients with methamphetamine (MA) dependence. Yet little is known about the possible gender difference. This study was performed to examine hippocampal volume in abstinent male and female MA users, and to further explore its relations...

Introduction: Movements to legalize medical and recreational marijuana (MJ) have ignited a sense of urgency to investigate effects of chronic MJ use in the human brain. While evidence has suggested that chronic MJ use alters brain structure and function, there is considerable heterogeneity in the findings (1,2). One consistent finding is that chron...

Objective The present study was to examine serum levels of brain-derived neurotrophic factor (BDNF), folate, homocysteine (Hcy), and their relationships with hippocampal volume and psychopathology in drug naïve, first episode schizophrenia. Method Drug naïve, first episode schizophrenia patients and healthy controls were enrolled in the study. Ser...

Background: Studies have shown that patients with schizophrenia and their siblings share decreased gray matter (GM) volumes in certain brain regions, which may represent candidate endophenotypes of schizophrenia. However, the specificity and utility of these possible endophenotypes in relation to schizophrenia remain unclear. Methods: Twenty dru...

Traumatic brain injury (TBI) is characterized by neuronal damage and commonly, secondary cell death, leading to functional and neurological dysfunction. Despite the recent focus of TBI research on developing therapies, affective therapeutic strategies targeting neuronal death associated with TBI remain underexplored. This study explored the efficac...

The 3rd Schizophrenia International Research Society Conference was held in Florence, Italy, April 14-18, 2012 and this year had as its emphasis, "The Globalization of Research". Student travel awardees served as rapporteurs for each oral session and focused their summaries on the most significant findings that emerged and the discussions that foll...

Introduction: Abnormalities in the fronto-striatal white matter tracts have been considered to be associated with cognitive dysfunction in schizophrenia1.2. Here, we investigate the alterations in fronto-striatal circuitry connecting the ventrolateral prefrontal cortex (VLPFC) and striatum over time in first-episode schizophrenia (FESZ). Methods: T...

Alterations in oscillatory brain activity are strongly correlated with cognitive performance in various physiological rhythms. The present study investigated whether the directionality of neural information flow (NIF) could be used to characterize the synaptic plasticity in thalamocortical (TC) pathway, and examined which frequency field oscillatio...

BACKGROUND: Many structural and functional studies have linked frontostriatal circuitry to cognitive dysfunction in schizophrenia, yet little is known about the change of this circuitry over time in the early stages of schizophrenia. This study examines structural changes in white matter tracts connecting the dorsolateral prefrontal cortex (DLPFC)...

Previous studies have shown gray matter volume reduction of superior temporal gyrus (STG) in chronic schizophrenia, yet only a few studies have examined the gray matter volume changes at the early phases of the illness and association with clinical symptoms. We thus evaluated whether or not volume reduction of STG is present in first-episode schizo...

To examine whether the directionality index of neural information flow (NIF) over specific oscillatory bands is useful in measuring synaptic plasticity, we employed the IM approach to determine the direction of NIF between the cortex and thalamus in normal and stressed animals. The experiment was performed by inducing long-term potentiation (LTP) o...

Background: Previous studies have shown that frontostriatal networks, especially involving dorsolateral prefrontal cortex (DLPFC) and ventrolateral prefrontal cortex (VLPFC), mediate cognitive functions which may be abnormal in schizophrenia. This study examined prefrontal striatal white matter connections in first-episode schizophrenics, and perfo...

In this paper, we propose a fast and novel probabilistic fiber tracking method for DTI data using the particle swarm tracking technique, which considers both the local fiber orientation distribution and the global fiber path in collaborative manner. We first construct a global optimization model that captures both global fiber path and the uncertai...

Growing evidence suggests the involvement of stress in the pathophysiology of depression. This study was designed to test behavioral and electrophysiological changes in a stressed model of depression. Rats were randomly divided into control and stressed groups. Chronic unpredictable stress combined with isolation rearing was applied in rats of stre...

This investigation examined whether the directionality of neural information flow could be used to index the measurement of synaptic plasticity in the chronic unpredictable stress (CUS) animals. Evolution map approach (EMA) was employed to determine the direction of information flow between the cortex and thalamus, while the experiment was performe...