Xi Mei’s research while affiliated with First Affiliated Hospital of China Medical University and other places

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Publications (30)


Detection locations. Green: frontopolar area (channels 7, 8, 9, 11, 25, 26, 27, and 28). Purple: left and right pars triangularis Broca areas (right, 22, 24, 37, and 39; left, 31, 32, 46, and 47). Red: left and right pre-motor and supplementary motor cortexes (right, 20 and 38; left, 36 and 48). Blue: left and right temporal cortexes (right, 1, 2, 3, 5, 17, 18, and 19; left, 13, 14, 15, 16, 33, 34, and 35). Yellow: left and right dorsolateral prefrontal cortexes (right, 4, 6, 21, 23, 40, 41, and 42; left 10, 12, 29, 30, 43, 44, and 45).
Flowchart of study participant enrollment and measurement protocols. AD, Alzheimer's disease; fNIRS, functional near-infrared spectroscopy; LBD, Lewy body disease; VFT, verbal fluency task.
Mean resting-state HbO concentrations (A) and functional connectivity (B) in patients with AD and LBD. Blue and orange bars: AD and LBD, respectively. AD, Alzheimer's disease; HbO, oxygenated hemoglobin; LBD, Lewy body disease; HbO, oxygenated hemoglobin; FC, functional connectivity. **p < 0.01.
Mean HbO (A) and slope of HbO concentrations (B) in various brain regions during the VFT. AD, Alzheimer's disease; HbO, oxygenated hemoglobin; LBD, Lewy body disease; VFT, verbal fluency task. *p < 0.05; **p < 0.01.
Blood parameters in the AD and LBD groups. We measured cognition-related blood biomarkers: total amyloid-β (Aβ), Aβ40, Aβ42, phosphorylated tau (p-tau), phosphorylated tau181 (p-tau181), α-synuclein (α-syn), neurofilament light (NFL), glial fibrillary acidic protein (GFAP). *p < 0.05.

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Relationships among cortical activation, cognition, and blood biomarkers in two types of dementia determined using functional near-infrared spectroscopy
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  • Full-text available

April 2025

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7 Reads

Nairong Ruan

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Ming Liang

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Yuehong Liu

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Chengying Zheng

Objective The most prevalent types of dementia in older adults are Alzheimer's disease (AD) and Lewy body dementia (LBD), and they have overlapping clinical symptoms. We aimed to define amounts of cortical activation and to identify indicators of brain function to better distinguish between these types of dementia and aid diagnosis using functional near-infrared spectroscopy (fNIRS). Methods Oxygenated hemoglobin (HbO) concentrations in the brains of patients with AD and LBD were detected using fNIRS. Brain function was assessed using a verbal fluency task (VFT). Resting-state and task-state cortical activations were investigated to determine differences between AD and LBD. Blood samples were analyzed to identify relevant biomarkers. The clinical and HbO variables were compared between AD and LBD. Functional connectivity at rest and correlations between HbO variables and blood biomarkers were analyzed. The sensitivity and specificity of the parameters for differentiating the dementias were evaluated using areas under the receiver operating characteristic (ROC) curves (AUCs). Results This study recruited 28 inpatients with AD and 25 with LBD. Mean HbO concentrations did not significantly differ in the resting state (p > 0.05), whereas functional connectivity significantly differed (t = −3.449, p = 0.001) between the groups. Mean HbO concentrations during the VFT, were significantly lower in the left temporal (p = 0.031), right dorsolateral prefrontal (p = 0.001), and right temporal (p = 0.011) cortices of the AD, than the LBD group. Blood amyloid-β (Aβ)42 levels were significantly higher in the AD group (p = 0.023), whereas significantly more α-synuclein was expressed in the LBD group (p = 0.012). Correlation analysis of cognition-related blood biomarkers with HbO concentrations associated higher plasma Aβ42 level with lower HbO concentrations in the right pre-motor and supplementary motor cortex (r = −0.378; p = 0.005) and higher glial fibrillary acidic protein (GFAP) levels in the lower right pars triangularis (r = −0.378; p = 0.006) at rest. Levels of the blood biomarker Aβ significantly and negatively correlated with HbO concentrations in the right temporal cortex (r = −0.329, p = 0.016) during the VFT. The AUC was significantly higher for the combination of multiple fNIRS indicators compared with individual cognitive or blood indicators (AUC = 0.9314). Conclusion The characteristics of HbO measured using fNIRS can help distinguish AD from LBD in older adults.

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Peripheral Single‐Cell Immune Characteristics Contribute to the Diagnosis of Alzheimer's Disease and Dementia With Lewy Bodies

January 2025

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5 Reads

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1 Citation

Objective Alzheimer's disease (AD) and dementia with Lewy bodies (DLB) are common neurodegenerative diseases with distinct but overlapping pathogenic mechanisms. The clinical similarities between these diseases often result in high misdiagnosis rates, leading to serious consequences. Peripheral blood mononuclear cells (PBMCs) are easy to collect and can accurately reflect the immune characteristics of both DLB and AD. Methods We utilized time‐of‐flight mass cytometry (CyTOF) with single‐cell resolution to quantitatively analyze peripheral PBMCs, identifying 1228 immune characteristics. Based on the top‐selected immune features, we constructed immunological elastic net (iEN) models. Results These models demonstrated high diagnostic efficacy in distinguishing diseased samples from healthy donors as well as distinguishing AD and DLB cases. The selected features reveal that the primary peripheral immune characteristic of AD is a decrease in total T cells, while DLB is characterized by low expression of I‐kappa‐B‐alpha (IKBα) in the classical monocyte subset. Conclusions These findings suggest that peripheral immune characteristics could serve as potential biomarkers, facilitating the diagnosis of neurodegenerative diseases.


Effect of bright-light therapy on depression and anxiety of a patient with Alzheimer’s disease combined with sleep disorder: A case report

December 2024

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6 Reads

World Journal of Psychiatry

BACKGROUND Alzheimer’s disease (AD) is a common type of dementia due to neuronal impairment. In addition, psychobehavioral symptoms including severe sleep disorders, depression and anxiety can occur in most patients with AD. CASE SUMMARY We report a case of a 68-year-old woman with a 2-year history of AD. She initially presented with memory loss, progressively more severe, leading to a depressive and anxious status. The clinical symptoms also included severe sleep disturbances. Considering the age and health state of the patient, a non-pharmacological treatment of bright light therapy was used to improve her sleep quality. The treatment was provided for 30 minutes twice a day, during 8:30 am to 9:00 am and 16:30 pm to 17:00 pm. After 4 weeks of therapy, the sleep quality notably improved, with a marked decrease in daytime sleep, increase in nighttime sleep, and disappearance of nocturnal activity. The depression and anxiety were also suppressed significantly. CONCLUSION This case report suggested that bright light therapy can have a positive effect on sleep quality in elderly patients with AD and can be used as an effective and safe non-pharmacological treatment.


FIGURE 1 Location of detection (A) and working memory protocol (B). (A) Green boxes represent the frontopolar area (channels 7, 8, 9, 11, 25, 26, 27, and 28); purple boxes represent the left and right pars triangularis Broca's area (22, 24, 37, 39 on the right and 31, 32, 46, 47 on the left); red boxes represent the left and right pre-motor and supplementary motor cortex (20, 38 on the right and 36, 48 on the left); blue boxes represent the left and right temporal cortex (1, 2, 3, 5, 17, 18, 19 on the right and13, 14, 15, 16, 33, 34, 35 on the left); yellow boxes represent the left and right dorsolateral prefrontal cortex (4, 6, 21, 23, 40, 41, 42 on the right and 10, 12, 29, 30, 43, 44, 45 on the left). (B) The working memory task structures comprised three blocks. A block (the green dotted box) consisted of 5 s resting time, 12 s encoding time (4 pictures × 3 s), 10 s retrieval time, 10 s resting time, 15 s non-working memory (NWM) time, and 5 s resting time. The baseline was the first 5 s resting time of the block.
Demographic and clinical data.
Cortical activation in elderly patients with Alzheimer’s disease dementia during working memory tasks: a multichannel fNIRS study

September 2024

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27 Reads

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3 Citations

Frontiers in Aging Neuroscience

Objective This study aimed to investigate cortical activation and functional connectivity in the cortex during working memory (WM) tasks in patients with Alzheimer’s disease (AD) using functional near-infrared spectroscopy (fNIRS). Methods A total of 17 older adults with AD and 17 cognitively normal (CN) participants were recruited. fNIRS was utilized to monitor oxygenated hemoglobin (HbO) concentrations in the frontotemporal lobe, while participants performed WM tasks to examine WM impairments in subjects with AD. Student’s t-test for continuous variables and the chi-square test for categorical variables were used to compare the clinical and HbO variables between the AD and CN groups. Functional connectivity was analyzed using Pearson’s correlation coefficient between the time series of each channel-to-channel pair. Results The changes in HbO concentrations and cortical activations during the WM task showed that the HbO concentration curve of the CN group was higher than that of the AD group during the encoding and maintenance phases of the WM task. Although in the brain region scale, there were no significant differences in average HbO concentrations between the two groups, many channels located in the frontal and temporal lobes showed significant differences ( p < 0.05) in the average HbO (channels 7 and 32) and slope HbO values (channels 7, 8, 9, 23, 30, 34, and 38) during the WM task. The average functional connectivity of the AD group was significantly lower than that of the CN group ( p < 0.05). The functional connectivity was stronger in the frontopolar (FP) region than in other areas in both groups. Conclusion This study revealed there were significant differences in HbO concentration in older adult patients with AD compared to CN during the WM task. The characteristics of HbO measured by the fNIRS technique can be valuable for distinguishing between AD and CN in older adults.


Effectiveness of anti-psychiatric treatment on visual and haptic perceptual disorder for a patient with Alzheimer’s disease: A case report

September 2024

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1 Citation

World Journal of Psychiatry

BACKGROUND Perception is frequently impaired in patients with Alzheimer’s disease (AD). Several patients exhibit visual or haptic hallucinations. CASE SUMMARY A 71-year-old Chinese man presented with visual and haptic hallucinations he had been experiencing for 2 weeks. The clinical manifestations were the feeling of insects crawling and biting the limbs and geison. He looked for the insects while itching and scratching, which led to skin breakage on the limbs. He was treated with topical and anti-allergic drugs in several dermatology departments without any significant improvement. After admission, the patient was administered risperidone (0.5 mg) and duloxetine (2 mg/day). One week later, the dose of risperidone was increased to 2 mg/day, and that of duloxetine was increased to 60 mg/day. After 2 weeks of treatment, the patient’s sensation of insects crawling and biting disappeared, and his mood stabilized. CONCLUSION This patient manifested psychiatric behavioral symptoms caused by AD brain atrophy. It was important to re-evaluate the patient’s cognitive-psychological status when the patient repeatedly went to the hospital for treatment. Follow-up attention to cognitive function and the consideration of perceptual deficits as early manifestations of AD should be considered.



Multi-branch attention Raman network and surface-enhanced Raman spectroscopy for the classification of neurological disorders

May 2024

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111 Reads

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1 Citation

Surface-enhanced Raman spectroscopy (SERS), a rapid, low-cost, non-invasive, ultrasensitive, and label-free technique, has been widely used in-situ and ex-situ biomedical diagnostics questions. However, analyzing and interpreting the untargeted spectral data remains challenging due to the difficulty of designing an optimal data pre-processing and modelling procedure. In this paper, we propose a Multi-branch Attention Raman Network (MBA-RamanNet) with a multi-branch attention module, including the convolutional block attention module (CBAM) branch, deep convolution module (DCM) branch, and branch weights, to extract more global and local information of characteristic Raman peaks which are more distinctive for classification tasks. CBAM, including channel and spatial aspects, is adopted to enhance the distinctive global information on Raman peaks. DCM is used to supplement local information of Raman peaks. Autonomously trained branch weights are applied to fuse the features of each branch, thereby optimizing the global and local information of the characteristic Raman peaks for identifying diseases. Extensive experiments are performed for two different neurological disorders classification tasks via untargeted serum SERS data. The results demonstrate that MBA-RamanNet outperforms commonly used CNN methods with an accuracy of 88.24% for the classification of healthy controls, mild cognitive impairment, Alzheimer’s disease, and Non-Alzheimer’s dementia; an accuracy of 90% for the classification of healthy controls, elderly depression, and elderly anxiety.



Common delirium assessment scales
Risk factors, preventive interventions, overlapping symptoms, and clinical measures of delirium in elderly patients

December 2023

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22 Reads

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9 Citations

World Journal of Psychiatry

Delirium is an acute reversible neuropsychiatric syndrome caused by multiple factors. It is associated with many adverse clinical outcomes including cognitive impairment, functional decline, prolonged hospitalization, and increased nursing service. The prevalence of delirium was high in department of cardiology, geriatric, and intensive care unit of hospital. With the increase in the aged population, further increases in delirium seem likely. However, it remains poorly recognized in the clinical practice. This article comprehensively discusses the latest research perspectives on the epidemiological data, risk factors, preventive interventions, overlapping symptoms, and clinical measures of delirium, including specific measures to manage delirium in clinical real-world situations. This article helps readers improve their knowledge and understanding of delirium and helps clinicians quickly identify and implement timely therapeutic measures to address various delirium subtypes that occur in the clinical settings to ensure patients are treated as aggressively as possible.


Overview of the study. (A) Protocol for bright light therapy in patients with AD and their caregivers (HC). (B) Light therapy modulated the EEG signal through the retina to the cortex. (C) HAMD scores, which reflect the level of depression in participants, may be change before and after therapy. (D) ① to ⑩ represent the relationship between the frontal and right temporal lobes, frontal and parietal lobes, frontal and left temporal lobes, right temporal and left temporal lobes, right temporal and parietal lobes, left temporal and parietal lobes, right temporal and occipital lobes, parietal and occipital lobes, left temporal and occipital lobes, frontal and occipital lobes.
Resting state EEG power of patients with AD and their caregivers with normal cognition (CN group) in the open-eye (A) and closed-eye (B) states at the frontal, left temporal, right temporal, parietal, and occipital lobes, and in the open-eye (C) and closed-eye (D) states in the delta (0–4 Hz), theta (4–8 Hz), alpha (8–13 Hz), and beta (13–30 Hz) bands. The gray and orange bars represent the HC and AD groups, respectively before (dark color) and after (light color) bright light therapy. Resting state EEG topographic maps of patients with AD and their care givers with normal cognition (HC group) in the open-eye (E) and closed-eyes (F) states. P1 and P2 represent different p values before and after therapy in the HC and AD groups, respectively.
EEG power network of the brain in patients with Alzheimer’s disease and cognitively normal controls. Pearson coefficient (r) was used to represent the connection strength between regions of the cortex. r values greater than 0.80, 0.85, 0.90 are represented by yellow, orange and red bars respectively.
Pearson correlation analysis of cognitive, blood, and EEG parameters. MMSE and ADAScog scores represent the cognitive levels of participants. The blood parameters included Aβ, Aβ40, Aβ42, IL-1β and MT. EEG parameters included the power of five lobes (frontal, left temporal, right temporal, parietal, and occipital lobes) and four bands (delta [0–4 Hz], theta [4–8 Hz], alpha [8–13 Hz] and beta [13–30 Hz]). The scale bar represents the Pearson coefficient, r (A) and p values (B). CE, closed-eye state; OE, open-eye state.
Antidepressant effect of bright light therapy on patients with Alzheimer’s disease and their caregivers

November 2023

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20 Reads

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1 Citation

Background: As a non-pharmacologic treatment, bright light therapy (BLT) is often used to improve affective disorders and memory function. In this study, we aimed to determine the effect of BLT on depression and electrophysiological features of the brain in patients with Alzheimer’s disease (AD) and their caregivers using a light-emitting diode device of 14000 lux. Methods: A 4-week case-control trial was conducted. Neuropsychiatric and electroencephalogram (EEG) examination were evaluated at baseline and after 4 weeks. EEG power in delta (1–4 Hz), theta (4–8 Hz), alpha (8–12 Hz), and beta (12–30 Hz) bands was calculated for our main analysis. Demographic and clinical variables were analyzed using Student’s t test and the chi-square test. Pearson’s correlation was used to determine the correlation between electrophysiological features, blood biochemical indicators, and cognitive assessment scale scores. Results: In this study, 22 in-patients with AD and 23 caregivers were recruited. After BLT, the Hamilton depression scale score decreased in the fourth week. Compared with the age-matched controls of their caregivers, a higher spectral power at the lower delta and theta frequencies was observed in the AD group. After BLT, the EEG power of the delta and theta frequencies in the AD group decreased. No change was observed in blood amyloid concentrations before and after BLT. Conclusion: In conclusion, a 4-week course of BLT significantly suppressed depression in patients with AD and their caregivers. Moreover, changes in EEG power were also significant in both groups.


Citations (18)


... fNIRS has been used to investigate and distinguish between different types of dementia and healthy older individuals or those with mild cognitive impairment (16,17). However, distinguishing between AD and DLB has not been investigated in detail, and more investigation is needed. ...

Reference:

Relationships among cortical activation, cognition, and blood biomarkers in two types of dementia determined using functional near-infrared spectroscopy
Functional connectivity and cerebral cortex activation during the resting state and verbal fluency tasks for patients with mild cognitive impairment, Lewy body dementia, and Alzheimer’s disease: A multi-channel fNIRS study
  • Citing Article
  • September 2024

Journal of Psychiatric Research

... Among the various types of analysis methods for the fNIRS modality, connectivity analysis evaluates the functional relationships within the brain 16 . Using connectivity analysis, previous studies have shown that task-based functional connectivity, which assesses brain activity in response to specific stimuli or challenges, is reduced in individuals with Alzheimer's disease, major depressive disorder, and attention-deficit/hyperactivity disorder [17][18][19] . Moreover, recent studies suggested that resting-state functional connectivity 20 , measuring inherent fluctuation of the brain activity, was impaired in patients with altered mentality in a consciousness-level dependent manner 21 . ...

Cortical activation in elderly patients with Alzheimer’s disease dementia during working memory tasks: a multichannel fNIRS study

Frontiers in Aging Neuroscience

... Delirium is a serious medical condition among the elderly, and this is due to its burden on the patient and healthcare system, as delirious patient needs frequent monitoring, extended hospitalization, and increased interventions, including diagnostic testing, pharmacological agents, restraints, and prolonged mechanical ventilation [7]. Awareness of risk factors of such a condition is important, there are multiple predisposing risk factors, such as advanced age, dementia, history of delirium, history of emotional disturbance, malnourishment, and visual and auditory impairment [8]. Also, there are some precipitating factors such as infection, electrolyte disturbance, sleep rhythm disorder, pain, acute somatic disease, and drugs [8]. ...

Risk factors, preventive interventions, overlapping symptoms, and clinical measures of delirium in elderly patients

World Journal of Psychiatry

... A literatura incluída na presente pesquisa, mostra uma relação entre idade, distúrbios do sono e declínio cognitivo (Mei et al., 2023). Sendo essa temática relatada também em um âmbito bidirecional, ou seja, tanto as alterações do sono influenciam no desenvolvimento de demências, quanto os déficits cognitivos também impactam na saúde do sono nos idosos (Smith, 2021;Lam, 2024). ...

Association of sleep disorders with clinical symptoms and age in Chinese older adult patients with and without cognitive decline

Frontiers in Aging Neuroscience

... In fact, the data revealed lower parietal cortex activation during the visuospatial task in depressed subjects, while no significant differences were found in verbal tasks. A recent study [16] highlighted NIRS as a promising method for distinguishing between subtypes of dementia: frontotemporal lobe dementia, Lewy body dementia, Parkinson's Disease Dementia (PDD), and Alzheimer's Disease (AD). Xi Mei and collaborators conducted an analysis on four patients during the VFT, working memory tasks, and resting states, comparing each patient's responses during NIRS recording. ...

Functional near-infrared spectroscopy in elderly patients with four types of dementia

World Journal of Psychiatry

... For example, Savitzky-Golay (SG) [14], wavelet transform (WT) [15], polynomial fitting-based correction [16], area normalization and min-max normalization [17], etc., can be used for steps of denoising, baseline correction and normalization in Raman data pre-processing. Machine learning (ML) models [13,[18][19][20], such as principal component analysis (PCA), partial least squares (PLS), support vector machine (SVM), and K-nearest neighbors (KNN) are the prevailing ways for Raman feature extraction and data modeling. However, in biomedical areas, due to the identification or classification problems in practical applications are always complex multi-classification tasks, these cumbersome traditional methods suffer a challenge in feature extraction and uncovering intricate patterns in such high-dimensional Raman data. ...

Identification of late-life depression and mild cognitive impairment via serum surface-enhanced Raman spectroscopy and multivariate statistical analysis

... According to the findings of earlier research, the prevalence of LLD is 28.4%~31.8% worldwide [2][3][4], and it might be higher among those who also have other underlying conditions. About 5% of older people in the community fulfill the DSM5 criteria [3], whereas 10%~16% of older adults patients still exhibit severe clinical symptoms of depression but do not yet meet the diagnostic criteria [4]. ...

Late-life depression: Epidemiology, phenotype, pathogenesis and treatment before and during the COVID-19 pandemic

... 26 Our earlier familial study indicated a potential link between MDD and mitochondrial ND1 T3394C mutations. 27 We also found two pedigrees associated with the mitochondrial ND6 T14502C mutation. The mitochondrial ND6 T14502C mutation may be associated with MDD. ...

Major depressive disorder is correlated with the mitochondrial ND1 T3394C mutation in two Han Chinese families: Two case reports

World Journal of Psychiatry

... A potential association between lithium and shifts towards morningness has been described (Xu et al., 2021). While sedative effects can be observed with other classes of pharmacological agents used in BD treatment, including antipsychotics (e.g., quetiapine immediate vs. prolonged-release), antidepressants (e. g., trazodone and surmontil) and benzodiazepines (Jing et al., 2023;Wang et al., 2023). Therefore, it is crucial to consider the psychopharmacological treatment in studies of this nature, and future research may explore the inclusion of patient subgroups based on their current pharmacological treatment. ...

A retrospective study of psychotropic drug treatments in bipolar disorder at acute and maintenance episodes

... The dual role of BAFF in both immune regulation and neuroprotection makes it an intriguing target for therapeutic intervention in AD, where modulating neuroinflammatory responses could slow disease progression. [167][168][169][170] The BCR signaling (a complex consisting of surface Ig and CD79A-CD79B) is the key phenomenon in the B cell maturation by mediating the crucial B lymphocyte education plan, positive and negative selection leading to the development of an immune-competent repertoire of B cells which could not react to self-antigens. 171,172 Immature B cells are lymphocytes able to migrate from the BM into the spleen and acquire CD21, CD22, and complete IgM as the surface Ig and are. ...

Targeting neuroinflammation in Alzheimer’s disease: from mechanisms to clinical applications

Neural Regeneration Research