Altered amplitude of low-frequency fluctuation in basal ganglia correlates to pulmonary ventilation function in COPD patients: A resting-state fMRI study

Decoding mechanisms and protein markers in lung-brain axis

BACKGROUND

The lung-brain axis represents a complex bidirectional communication network that is pivotal in the crosstalk between respiratory and neurological functions. This review summarizes the current understanding of the mechanisms and protein markers that mediate the effects of lung diseases on brain health.

MAIN FINDINGS

In this review, we explore the mechanisms linking lung injury to neurocognitive impairments, focusing on neural pathways, immune regulation and inflammatory responses, microorganism pathways, and hypoxemia. Specifically, we highlight the role of the vagus nerve in modulating the central nervous system response to pulmonary stimuli; Additionally, the regulatory function of the immune system is underscored, with evidence suggesting that lung-derived immune mediators can traverse the blood-brain barrier, induce neuroinflammation and cognitive decline; Furthermore, we discuss the potential of lung microbiota to influence brain diseases through microbial translocation and immune activation; Finally, the impact of hypoxemia is examined, with findings indicating that it can exacerbate cerebral injury via oxidative stress and impaired perfusion. Moreover, we analyze how pulmonary conditions, such as pneumonia, ALI/ARDS, and asthma, contribute to neurological dysfunction. Prolonged mechanical ventilation can also contribute to cognitive impairment. Conversely, brain diseases (e.g., stroke, traumatic brain injury) can lead to acute respiratory complications. In addition, protein markers such as TLR4, ACE2, A-SAA, HMGB1, and TREM2 are crucial to the lung-brain axis and correlate with disease severity. We also discuss emerging therapeutic strategies targeting this axis, including immunomodulation and microbiome engineering. Overall, understanding the lung-brain interplay is crucial for developing integrated treatment strategies and improving patient outcomes. Further research is needed to elucidate the molecular mechanisms and foster interdisciplinary collaboration.

Neuroimaging insights into lung disease-related brain changes: from structure to function

Lung diseases induce changes in brain structure and function, leading to a range of cognitive, emotional, and motor deficits. The concept of the lung-brain axis has been proposed through neuroanatomy, endocrine, and immune pathway, while a considerable number of studies also explored the existence of the lung-brain axis from a neuroimaging perspective. This survey summarizes studies exploring the relationship between lung disease and brain structure and function from neuroimaging perspective, particular in magnetic resonance imaging (MRI). We have collated existing lung diseases studies and categorized them into four types: chronic obstructive pulmonary disease (COPD), coronavirus disease 2019 (COVID-19), lung cancer and other lung diseases. The observed structural and functional changes in the brain and cognitive dysfunction induced by lung diseases are discussed. We also present distinct pattern of brain changes in various lung diseases. Neuroimaging changes in COPD are concentrated in the frontal lobes, including gray matter atrophy, white matter damage, and reduced perfusion. Patients with COVID-19 exhibit extensive microhemorrhages and neuroinflammation, brain regions functionally connected to the primary olfactory cortex show greater changes. For lung cancer patients, brain changes are mainly attributed to the neurotoxicity of radiotherapy and chemotherapy, with damage concentrated in subcortical structures, patients with cancer pain demonstrate hyperconnectivity in motor and visual networks. The survey also discusses the pathological mechanisms revealed in neuroimaging studies and clinical significance of current studies. Finally, we analyzed current limitations, mainly in terms of small sample size, non-standardized criteria, reliance on correlation analyses, lack of longitudinal studies, and absence of reliable biomarkers. We suggest future research directions should include leveraging artificial intelligence for biomarker development, conducting longitudinal and multicenter studies, and investigating the systemic effects of lung disease on the brain and neuromodulation strategies.

The Abnormal Alternations of Brain Imaging in Patients with Chronic Obstructive Pulmonary Disease: A Systematic Review

Background

Cognitive impairment (CI) is an important extrapulmonary complication in patients with chronic obstructive pulmonary disease (COPD). Multimodal Neuroimaging Examination can display changes in brain structure and functions in patients with COPD.

Objective

The purpose of this systematic review is to provide an overview of the variations in brain imaging in patients with COPD and their potential relationship with CI. Furthermore, we aim to provide new ideas and directions for future research.

Methods

Literature searches were performed using the electronic databases PubMed, Scopus, and ScienceDirect. All articles published between January 2000 and November 2021 that met the eligibility criteria were included.

Results

Twenty of the 23 studies focused on changes in brain structure and function. Alterations in the brain's macrostructure are manifested in the bilateral frontal lobe, hippocampus, right temporal lobe, motor cortex, and supplementary motor area. The white matter microstructural changes initially appear in the bilateral frontal subcortical region. Regarding brain function, patients with COPD exhibited reduced frontal cerebral perfusion and abnormal alterations in intrinsic brain activity in the bilateral posterior cingulate cortex, precuneus, right lingual gyrus, and left anterior central gyrus. Currently, there is limited research related to brain networks.

Conclusion

CI in patients with COPD may present as a type of dementia different from Alzheimer's disease, which tends to manifest as frontal cognitive decline early in the disease. Further studies are required to clarify the neurobiological pathways of CI in patients with COPD from the perspective of brain connectomics based on the whole-brain system in the future.

Effect of Acupuncture on Neuroplasticity of Stroke Patients with Motor Dysfunction: A Meta-Analysis of fMRI Studies

Objective

To analyze the pattern of intrinsic brain activity variability that is altered by acupuncture compared with conventional treatment in stroke patients with motor dysfunction, thus providing the mechanism of stroke treatment by acupuncture.

Methods

Chinese and English articles published up to May 2020 were searched in the PubMed, Web of Science, EMBASE, and Cochrane Library databases, China National Knowledge Infrastructure, Chongqing VIP, and Wanfang Database. We only included randomized controlled trials (RCTs) using resting-state fMRI to observe the effect of acupuncture on stroke patients with motor dysfunction. R software was used to analyze the continuous variables, and Seed-based d Mapping with Permutation of Subject Images (SDM-PSI) was used to perform an analysis of fMRI data. Findings. A total of 7 studies comprising 143 patients in the treatment group and 138 in the control group were included in the meta-analysis. The results suggest that acupuncture treatment helps the healing process of motor dysfunction in stroke patients and exhibits hyperactivation in the bilateral basal ganglia and insula and hypoactivation in motor-related areas (especially bilateral BA6 and left BA4).

Conclusion

Acupuncture plays a role in promoting neuroplasticity in subcortical regions that are commonly affected by stroke and cortical motor areas that may compensate for motor deficits, which may provide a possible mechanism underlying the therapeutic effect of acupuncture.

Abnormal Static and Dynamic Local-Neural Activity in COPD and Its Relationship With Pulmonary Function and Cognitive Impairments

Patients with chronic obstructive pulmonary disease (COPD) are characterized by attenuated pulmonary function and are frequently reported with cognitive impairments, especially memory impairments. The mechanism underlying the memory impairments still remains unclear. We applied resting-state functional magnetic resonance imaging (RS-fMRI) to compare the brain local activities with static and dynamic amplitude of low-frequency fluctuations (sALFF, dALFF) among patients with COPD (n = 32) and healthy controls (HC, n = 30). Compared with HC, COPD patients exhibited decreased sALFF in the right basal ganglia and increased dALFF in the bilateral parahippocampal/hippocampal gyrus. The reduced the left basal ganglia was associated with lower oxygen partial pressure. Besides, the increased dALFF in the left hippocampal/parahippocampal cortex was associated with poor semantic-memory performance and the increased dALFF in the left hippocampal/parahippocampal cortex was associated the forced vital capacity. The present study revealed the abnormal static and dynamic local-neural activities in the basal ganglia and parahippocampal/hippocampal cortex in COPD patient and its relationship with poor lung function and semantic-memory impairments.

The Relationship Between Chronic Obstructive Pulmonary Disease and Cerebral Small Vessel Disease Assessed by Magnetic Resonance Imaging: A Case-Control Study from a Single Center in Beijing, China

Background

Chronic obstructive pulmonary disease (COPD) and cerebral small vessel disease (CSVD) reportedly share similar risk factors and pathogenesis. However, the relationship between these 2 diseases is not clear. This study aimed to investigate the association between COPD and CSVD.

Material/Methods

Patients with stable COPD and matched healthy control participants were recruited for this study. Clinical characteristics were collected based on medical history, serological tests, brain magnetic resonance imaging, and pulmonary function tests. Individual CSVD imaging markers (white matter hyperintensities [WMH], enlarged perivascular space [EPVS], and brain atrophy) were assessed to determine their severity. Logistic analysis was used to test the relationship between CSVD markers and COPD.

Results

Significant differences in WMH, basal ganglia EPVS (BG-EPVS), and centrum semiovale EPVS (CSO-EPVS) were found between COPD and control groups (P<0.001). Logistic analysis showed that COPD was a risk factor for WMH (odds ratio [OR]=2.467, 95% confidence interval [95% CI]: 1.550–3.927, P<0.001), while it was a protective factor for BG-EPVS (OR=0.391, 95% CI: 0.246–0.621, P<0.001) and CSO-EPVS (OR=0.053, 95% CI: 0.021–0.138, P<0.001). Among patients in the COPD group, duration of COPD was a risk factor for WMH (P<0.001) and BG-EPVS (P=0.047, 0.013, 0.746), while there was no significant correlation between the COPD grade and the severity of WMH and BG-EPVS (P>0.05).

Conclusions

A significant correlation exists between COPD and imaging markers of CSVD, including WMH, BG-EPVS, and CSO-EPVS. In addition, the severity of WMH and BG-EPVS is positively related to the duration of COPD, suggesting that COPD may be a risk factor for CSVD.

The Application of rs-fMRI in Vascular Cognitive Impairment

The incidence of vascular cognitive impairment (VCI) has been increasing for years and has become a major disabling factor in middle-aged and elderly populations. The pathogenesis of VCI is unclear, and there are no standard diagnostic criteria. Resting-state functional magnetic resonance imaging (rs-fMRI) can be used to detect spontaneous brain functional activity in a resting state, which facilitates in-depth investigation of the pathogenesis of VCI and provides an objective reference for early diagnosis, differential diagnosis, and prognostic evaluation. This article mainly reviews the principle and analysis of rs-fMRI data, as well as the progress of its application for VCI diagnosis.

Altered amplitude of low-frequency fluctuation in basal ganglia correlates to pulmonary ventilation function in COPD patients: A resting-state fMRI study

INTRODUCTION

Patients under chronic obstructive pulmonary disease (COPD) has been reported to be associated with a higher prevalence of cognitive impairment (CI). However, it is still largely unknown whether the aberrant resting-state spontaneous neuronal activity pattern reflected by the amplitude of low-frequency fluctuation (ALFF) analysis will be associated with the CI in COPD patients.

MATERIALS

A total of 28 COPD patients and 26 healthy controls were enrolled in this study. Of all the subjects, structural and functional MRI data, spirometry tests performance and neuropsychological assessments of different cognitive domains were collected. Voxel-based two-sample t tests were used to detect brain regions showing differences in the ALFF value between COPD patients and healthy controls. An additional fMRI runs with supplementary oxygen delivery were employed to explore the impact of elevated partial pressure of oxygen (PaO₂ ) or moderate hyperoxia on ALFF in COPD patients and healthy controls respectively.

RESULTS

More extensive white matter lesion was detected in COPD patients. COPD patients exhibit decreased ALFF value in bilateral basal ganglia areas and right thalamus, and aberrant ALFF value is correlated with PaO₂ and pulmonary ventilation function (FEV1%pred). COPD patients performed worse in the Digit Span Test (reverse), Digit Symbol Substitution Test, Trail-making test (A and B) than controls. After supplementary oxygen inhalation, the ALFF value of basal ganglia and right thalamus significantly increased in the controls, but not in the COPD patients.

CONCLUSIONS

COPD patients mainly exhibit impaired executive function but not long-term memory in cognitive function assessment. Aberrant ALFF alteration in the deep brain may be directly related to lower PaO₂ in COPD patients.