Frontiers in Aging Neuroscience

Mechanisms of ozone-induced neurotoxicity in the development and progression of dementia: a brief review
Marin-Castañeda LA, Gonzalez-Garibay G, Garcia-Quintana I, Pacheco-Aispuro G and Rubio C
Dementia encompasses a spectrum of neurodegenerative disorders significantly impacting global health, with environmental factors increasingly recognized as crucial in their etiology. Among these, ozone, has been identified as a potential exacerbator of neurodegenerative processes, particularly in Alzheimer's disease (AD). Ozone exposure induces the production of reactive oxygen species (ROS), which penetrate the BBB, leading to oxidative damage in neuronal cells. This oxidative stress is closely linked with mitochondrial dysfunction and lipid peroxidation, processes that are foundational to the pathology observed in dementia, such as neuronal death and protein aggregation. Furthermore, ozone triggers chronic neuroinflammation, exacerbating these neurodegenerative processes and perpetuating a cycle of CNS damage. Recent studies highlight the role of peripheral biomarkers like High Mobility Group Box 1 (HMGB1) and Triggering Receptor Expressed on Myeloid cells 2 (TREM2) in mediating ozone's effects. Disruption of these and other identified proteins by ozone exposure impairs microglial function and response to amyloid plaques, suggesting a novel pathway through which ozone may influence AD pathology via immune dysregulation. This review discusses the concept of a bidirectional lung-brain axis, illustrating that systemic responses to air pollutants like ozone may reflect and contribute to neurodegenerative processes in the CNS. By delineating these mechanisms, we emphasize the critical need for integrating environmental health management into strategies for the prevention and treatment of dementia.
A bibliometric analysis of the relationship between traumatic brain injury and Alzheimer's disease (1993-2023)
Hu JH, Zhang X, Yang HM, Xu YL, Zhang M and Niu X
Traumatic brain injury (TBI) increases the risk of developing Alzheimer's disease (AD), and a growing number of studies support a potential link between the two disorders. Therefore, the objective of this study is to systematically map the knowledge structure surrounding this topic over the past and to summarize the current state of research and hot frontiers in the field.
Elevated circulating levels of GFAP associated with reduced volumes in hippocampal subregions linked to mild cognitive impairment among community-dwelling elderly individuals
Zhang Y, Wang J, Zhang H, Tan Z, Zheng Y, Ping J, Zhang J, Luo J, Li L, Lu L and Liu X
Cerebrospinal fluid biomarkers are challenging to use for diagnosing mild cognitive impairment (MCI) in large populations, and there is an urgent need for new blood biomarkers. The aim of this study is to investigate whether astrocyte activation is correlated with hippocampal atrophy, and to assess the potential of glial fibrillary acidic protein (GFAP) as a biomarker for diagnosing MCI among community-dwelling older individuals.
Abnormal outer and inner retina in a mouse model of Huntington's disease with age
Yang D, Huang C, Guo X, Li Y, Wu J, Zhang Z, Yan S and Xu Y
Huntington's disease (HD) is a progressive neurodegenerative disorder characterized by motor dysfunction and cognitive decline. While retinal abnormalities have been documented in some HD patients and animal models, the nature of these abnormalities-specifically whether they originate in the inner or outer retina-remains unclear, particularly regarding their progression with age. This study investigates the retinal structure and function in HD transgenic mice (R6/1) compared to C57BL/6 J control mice at 2, 4, and 6 months of age, encompassing both pre-symptomatic and symptomatic stages of HD. Pathological assessments of the striatum and evaluations of motor function confirmed significant HD-related alterations in R6/1 mice at 6 months. Visual function was subsequently analyzed, accompanied by immunofluorescent staining of retinal and optic nerve tissues over time. Our findings revealed that R6/1 mice exhibited pronounced HD symptoms at 6 months, characterized by neuronal loss in the striatum and impaired locomotor abilities. Functionally, visual acuity declined at 6 months, while retinal light responses began to deteriorate by 4 months. Structurally, R6/1 mice demonstrated a global reduction in cone opsin expression as early as 2 months, with a decrease in rhodopsin levels at 4 months, alongside a thinner retinal structure compared to controls. Notably, rod bipolar cell populations were decreased at 6 months, exhibiting shorter dendritic branches and reduced synaptic connections with photoreceptors in the outer retina. Additionally, ganglion cell numbers in the inner retina decreased at 6 months, accompanied by aberrant neural fibers in the optic nerve. Microglial activation was evident at 4 months, while astrocytic activation was observed at 6 months. Aggregates of mutant huntingtin (mHTT) were first detected in the ganglion cell layer and optic nerve at 2 months, subsequently disseminating throughout all retinal layers with advancing age. These results indicate that retinal pathology in R6/1 mice manifests earlier in the outer retina than in the inner retina, which does not align with the progression of mHTT aggregation. Consequently, the R6/1 mouse retina may serve as a more effective model for elucidating the mechanisms underlying HD and evaluating potential therapeutic strategies, rather than functioning as an early diagnostic tool for the disease.
Nasal lymphatic obstruction of CSF drainage as a possible cause of Alzheimer's disease and dementia
Phillips WT and Schwartz JG
Alzheimer's disease, the most common form of dementia among older adults, slowly destroys memory and thinking skills. In recent years, scientists have made tremendous progress in understanding Alzheimer's disease, still, they do not yet fully understand what causes the disease. This article proposes a novel etiology for Alzheimer's disease. Our hypothesis developed from a review of nuclear medicine scans, in which the authors observed a significant increase in nasal turbinate vasodilation and blood pooling in patients with hypertension, sleep apnea, diabetes and/or obesity, all risk factors for Alzheimer's disease. The authors propose that nasal turbinate vasodilation and resultant blood pooling lead to the obstruction of normal nasal lymphatic clearance of cerebrospinal fluid and its waste products from the brain. The nasal turbinate vasodilation, due to increased activity, occurs alongside the well-established increased activity of the cardiovascular system as seen in patients with hypertension. The increased parasympathetic activity is likely due to an autonomic imbalance secondary to the increase in worldwide consumption of highly processed food associated with dysregulation of the glucose regulatory system. The authors' hypothesis offers a novel mechanism and a new paradigm for the etiology of Alzheimer's disease and helps explain the rapid worldwide rise in the disease and other dementias which are expected to double in the next 20 years. This new paradigm provides compelling evidence for the modulation of the parasympathetic nervous system as a novel treatment strategy for Alzheimer's disease and other degenerative brain diseases, specifically targeting nasal turbinate lymphatic flow.
Somatosensory integration in robot-assisted motor restoration post-stroke
Lin L, Qing W, Zheng Z, Poon W, Guo S, Zhang S and Hu X
Disruption of somatosensorimotor integration (SMI) after stroke is a significant obstacle to achieving precise motor restoration. Integrating somatosensory input into motor relearning to reconstruct SMI is critical during stroke rehabilitation. However, current robotic approaches focus primarily on precise control of repetitive movements and rarely effectively engage and modulate somatosensory responses, which impedes motor rehabilitation that relies on SMI. This article discusses how to effectively regulate somatosensory feedback from target muscles through peripheral and central neuromodulatory stimulations based on quantitatively measured somatosensory responses in real time during robot-assisted rehabilitation after stroke. Further development of standardized recording protocols and diagnostic databases of quantitative neuroimaging features in response to post-stroke somatosensory stimulations for real-time precise detection, and optimized combinations of peripheral somatosensory stimulations with robot assistance and central nervous neuromodulation are needed to enhance the recruitment of targeted ascending neuromuscular pathways in robot-assisted training, aiming to achieve precise muscle control and integrated somatosensorimotor functions, thereby improving long-term neurorehabilitation after stroke.
Decrease in walking ability with increased functional connectivity between multiple brain areas in Parkinson's disease: a functional near-infrared spectroscopy study
Wang J, Lu J, Wang Y, Shu Z, Cheng Y, Zhang X, Yu Y, Han J, Zhu Z, Yu N and Wu J
Gait disturbances significantly impact the mobility and quality of life of individuals with Parkinson's disease (PD). This study aims to delve into the cortical mechanisms underlying gait disorders in PD, specifically focusing on the prefrontal cortex (PFC), premotor cortex (PMC), and primary somatosensory cortex (PSC).
Longitudinal accelerated brain age in mild cognitive impairment and Alzheimer's disease
Ly M, Yu G, Son SJ, Pascoal T, Karim HT and
Brain age is a machine learning-derived estimate that captures lower brain volume. Previous studies have found that brain age is significantly higher in mild cognitive impairment and Alzheimer's disease (AD) compared to healthy controls. Few studies have investigated changes in brain age longitudinally in MCI and AD. We hypothesized that individuals with MCI and AD would show heightened brain age over time and across the lifespan. We also hypothesized that both MCI and AD would show faster rates of brain aging (higher slopes) over time compared to healthy controls.
Corrigendum: Lipid profiles in the cerebrospinal fluid of rats with 6-hydroxydopamine-induced lesions as a model of Parkinson's disease
Qiu J, Peng G, Tang Y, Li S, Liu Z, Zheng J, Wang Y, Liu H, Wei L, Su Y, Lin Y, Dai W, Zhang Z, Chen X, Ding L, Guo W, Zhu X, Xu P and Mo M
[This corrects the article DOI: 10.3389/fnagi.2022.1077738.].
Editorial: Dance, embodied agency and neuroplasticity in aging
Batson GB, Bläsing BE, DeSouza JFX, Haas AN and Hugenschmidt CE
Network-based statistics reveals an enhanced subnetwork in prefrontal cortex in mild cognitive impairment: a functional near-infrared spectroscopy study
Wu P, Lv Z, Bi Y, Li Y, Chen H, Jiang J, Pang S, Zhao X and Jiang W
Mild cognitive impairment (MCI) is generally considered to have a high risk of progression to Alzheimer's disease. Our study aimed to investigate the abnormal functional connectivity (FC) in prefrontal cortex (PFC) in patients with MCI and explore the relationship between the observed changes and cognitive function.
Association of serum klotho with cognitive function among individuals with nonalcoholic fatty liver disease
Wu F, Pan J, Chen M, Lai X, Gu Y, Pei L and Yang L
This study investigated the potential link between serum klotho levels and cognitive function in patients with non-alcoholic fatty liver disease (NAFLD).
Causal association between Parkinson's disease and cancer: a bidirectional Mendelian randomization study
Tang C, Fu P, Lin L, Zhou H, Huang Y, Li Y and Zhao S
Previous observational research has indicated a correlation between Parkinson's disease (PD) and multiple cancers; but the causality remains unclear. Thus, we utilized Mendelian randomization (MR) analysis to explore the potential causal link between PD and various cancers.
Hyperthyroidism, hypothyroidism, thyroid stimulating hormone, and dementia risk: results from the NHANES 2011-2012 and Mendelian randomization analysis
Sheng X, Gao J, Chen K, Zhu X and Wang Y
As the world ages, dementia places a heavy burden on society and the economy, but current methods of diagnosing dementia are still limited and there are no better therapies that target the causes of dementia. The purpose of this work is to explore the relationship between thyroid disease, thyroid stimulating hormone (TSH) concentrations, free tetraiodothyronine (FT4) concentrations and cognitive function.
P1 evoked by facial expression images is enhanced in Parkinson's disease patients with depressive symptoms
Sun Y, Mo Y, Peng C, Li Q, Wang Z, Xue S and Zhang S
Depressive symptoms are most common non-motor symptoms in Parkinson's disease (PD), which is often overlooked due to absence of rapid and objective diagnostic biomarkers. Electroencephalography (EEG)-based event-related potentials (ERPs) is commonly used to assess emotional processes. The aim of this study was to investigate changes in ERPs in PD patients exhibiting depressive symptoms and to provide a reliable biomarker for assisting in the diagnosis of PD with depressive symptoms.
Immediate modulatory effects of transcutaneous vagus nerve stimulation on patients with Parkinson's disease: a crossover self-controlled fMRI study
Fu C, Hou X, Zheng C, Zhang Y, Gao Z, Yan Z, Ye Y and Liu B
Previous studies have evaluated the safety and efficacy of transcutaneous auricular vagus nerve stimulation (taVNS) for the treatment of Parkinson's disease (PD). However, the mechanism underlying the effect of taVNS on PD remains to be elucidated. This study aimed to investigate the immediate effects of taVNS in PD patients.
Biomarkers and Alzheimer's disease: a bibliometric analysis
Yang L, Zeng J, Li L and Zhang Y
The diagnosis and treatment of biomarkers in Alzheimer's disease has emerged as a prominent topic within Alzheimer's disease research. In this paper, we conducted a bibliometric analysis of data from a wide range of literature in this field to enhance the in-depth understanding of this area.
TLR4-mediated chronic neuroinflammation has no effect on tangle pathology in a tauopathy mouse model
Basheer N, Muhammadi MK, Freites CL, Avila M, Momand MUD, Hryntsova N, Smolek T, Katina S and Zilka N
Alzheimer's disease (AD) is marked by the accumulation of fibrillary aggregates composed of pathological tau protein. Although neuroinflammation is frequently observed in conjunction with tau pathology, current preclinical evidence does not sufficiently establish a direct causal role in tau tangle formation. This study aimed to evaluate whether chronic Toll-like receptor 4 (TLR4) stimulation, induced by a high dose of lipopolysaccharide (LPS, 5 mg/kg), exacerbates neurofibrillary tangle (NFT) pathology in a transgenic mouse model of tauopathy that expresses human truncated 151-391/3R tau, an early feature of sporadic AD.
Association between focal amyloid deposition and cognitive impairment in individuals below the amyloid threshold
Ham H, Kim BC, Lee EH, Shin D, Jang H, Kang SH, Yun J, Kim HJ, Na DL, Kim JP, Seo SW and Cho SH
This study aimed to investigate the characteristics of individuals with amyloid levels below the threshold. To achieve this, we differentiated between two groups: those with global amyloid negativity but focal deposition [G(-)F(+)] and those without focal deposition [G(-)F(-)].
Post-stroke fatigue and its correlation with family functioning in patients who have experienced a first episode of stroke
Zhu R, Huang H, Yu Y, Bao S, Lin N and Shu M
This study aimed to analyse the relevant factors that may affect post-stroke fatigue (PSF) in patients with stroke and further explore the correlation between family functioning and PSF.
Clinical and cognitive features associated with psychosis in Parkinson's disease: a longitudinal study
Flanigan JL, Harrison MB, Patrie JT, Shah BB, Sperling SA, Wyman-Chick KA, Dalrymple WA and Barrett MJ
Parkinson's disease psychosis (PDPsy) is associated with increased nursing home placement and mortality and is closely linked with cognitive dysfunction.