Auditory Brainstem Dysfunction, Non-Invasive Biomarkers for Early Diagnosis and Monitoring of Alzheimer’s Disease in Young Urban Residents Exposed to Air Pollution

Adjunct Methods for Alzheimer's Disease Detection: A Review of Auditory Evoked Potentials

The auditory afferent pathway as a clinical marker of Alzheimer's disease (AD) has sparked interest in investigating the relationship between age-related hearing loss (ARHL) and AD. Given the earlier onset of ARHL compared to cognitive impairment caused by AD, there is a growing emphasis on early diagnosis and intervention to postpone or prevent the progression from ARHL to AD. In this context, auditory evoked potentials (AEPs) have emerged as a widely used objective auditory electrophysiological technique for both the clinical diagnosis and animal experimentation in ARHL due to their non-invasive and repeatable nature. This review focuses on the application of AEPs in AD detection and the auditory nerve system corresponding to different latencies of AEPs. Our objective was to establish AEPs as a systematic and non-invasive adjunct method for enhancing the diagnostic accuracy of AD. The success of AEPs in the early detection and prediction of AD in research settings underscores the need for further clinical application and study.

Obstructive sleep apnea and amyloid-β42 in adolescents: The results of a pilot study

Background. Obstructive sleep apnea (OSA) is a chronic condition characterized by repetitive collapse of the upper airway during sleep leading to intermittent hypoxia, excessive arousals and disrupt of sleep homeostasis. OSA is associated with obesity as well as pathological dynamics of cerebral beta-amyloid and dementia.The aim. Comparative assessment of the plasma beta-amyloid 42 levels in adolescents, depending on the presence or absence of OSA and obesity.Materials and methods. Seventy-four obese and non-obese male adolescents were included in the study. All participants underwent polysomnography to verify OSA and measure sleep parameters, and venipuncture for the assessment of betaamyloid 42 by enzyme-linked immunosorbent assay (ELISA).Results. After polysomnography all adolescents have been divided into four study groups: OSA obese (group 1; n = 28); non-OSA obese (group 2; n = 20); OSA non-obese (group 3; n = 11), and non-OSA non-obese (group 4 – control; n = 15). OSA obese adolescents had significant elevations in beta-amyloid 42 plasma levels compared with participants from three other groups (р = 0.007, p = 0.047 and p = 0.0002, correspondingly). Compared to both OSA non-obese adolescents and the control group, non-OSA obese patients had similar beta-amyloid 42 blood concentrations (p = 0.167 and p = 0.155, correspondingly). However, patients from the group 3 showed significantly higher beta-amyloid 42 plasma levels than controls (p = 0.004).Conclusions. Thus, OSA, accompanied by intermittent nocturnal hypoxia, and particularly OSA and obesity comorbidity, in adolescents is associated with increased beta-amyloid 42 circulating concentrations, which has a major role in pathogenesis of dementia. Beta-amyloid 42 plasma level may be recommended for use as early biomarker of cognitive impairment and neurodegenerative diseases, but future researches are needed.

Pure Tone Audiometry and Hearing Loss in Alzheimer's Disease: A Meta-Analysis

An association between age-related hearing loss (ARHL) and Alzheimer's Disease (AD) has been widely reported. However, the nature of this relationship remains poorly understood. Quantification of hearing loss as it relates to AD is imperative for the creation of reliable, hearing-related biomarkers for earlier diagnosis and development of ARHL treatments that may slow the progression of AD. Previous studies that have measured the association between peripheral hearing function and AD have yielded mixed results. Most of these studies have been small and underpowered to reveal an association. Therefore, in the current report, we sought to estimate the degree to which AD patients have impaired hearing by performing a meta-analysis to increase statistical power. We reviewed 248 published studies that quantified peripheral hearing function using pure-tone audiometry for subjects with AD. Six studies, with a combined total of 171 subjects with AD compared to 222 age-matched controls, met inclusion criteria. We found a statistically significant increase in hearing threshold as measured by pure tone audiometry for subjects with AD compared to controls. For a three-frequency pure tone average calculated for air conduction thresholds at 500-1,000-2,000 Hz (0.5-2 kHz PTA), an increase of 2.3 decibel hearing level (dB HL) was found in subjects with AD compared to controls (p = 0.001). Likewise, for a four-frequency pure tone average calculated at 500-1,000-2,000-4,000 (0.5-4 kHz PTA), an increase of 4.5 dB HL was measured (p = 0.002), and this increase was significantly greater than that seen for 0.5-2 kHz PTA. There was no difference in the average age of the control and AD subjects. These data confirm the presence of poorer hearing ability in AD subjects, provided a quantitative estimate of the magnitude of hearing loss, and suggest that the magnitude of the effect is greater at higher sound frequencies. Systematic Review Registration: https://www.crd.york.ac.uk/prospero/, identifier: CRD42021288280.

Brainstem auditory evoked potential in cognitive impairment in patients with type 2 diabetes mellitus

PURPOSE

Type 2 diabetes mellitus (T2DM) can cause mild cognitive impairment (MCI) which threatens the health of patients. So the diagnosis of MCI is particularly important. It is reported that brainstem auditory evoked potential (BAEP) is a sensitive tool to detect the brainstem function in patients with T2DM. This study aimed to investigate the relationship between BAEP and MCI in patients with T2DM.

METHODS

A total of 244 T2DM patients with normal hearing, including 117 normal cognition patients and 127 MCI patients, were recruited in this cross-sectional study. Each subject underwent the BAEP examination. The diagnosis of MCI was based on the diagnostic guideline developed by the National Institute on Aging-Alzheimer's Association workgroups. The Montreal Cognitive Assessment (MoCA) was used to assess the cognitive function of the subjects.

RESULTS

Compared with the normal cognition group, the patients in the MCI group had longer latencies of waves III and V and interpeak latencies (IPL) I-V in both ears (P < 0.05). The significant negative correlations were found between the latencies of waves III, V, IPL I-V, and MoCA score in both ears (P < 0.05). Logistic regression showed that the prolongations of latunits of waves III and V and IPL I-V in both ears were still associated with MCI after adjustment for mixed factors (P < 0.05).

CONCLUSION

These results indicate abnormal auditory pathway in brainstem of T2DM patients with MCI. BAEP may contribute to the clinical diagnosis of MCI in patients with T2DM.

Quadruple abnormal protein aggregates in brainstem pathology and exogenous metal-rich magnetic nanoparticles (and engineered Ti-rich nanorods). The substantia nigrae is a very early target in young urbanites and the gastrointestinal tract a key brainstem portal

Fine particulate air pollution (PM_2.5) exposures are linked with Alzheimer's and Parkinson's diseases (AD,PD). AD and PD neuropathological hallmarks are documented in children and young adults exposed lifelong to Metropolitan Mexico City air pollution; together with high frontal metal concentrations (especially iron)-rich nanoparticles (NP), matching air pollution combustion- and friction-derived particles. Here, we identify aberrant hyperphosphorylated tau, ɑ synuclein and TDP-43 in the brainstem of 186 Mexico City 27.29 ± 11.8y old residents. Critically, substantia nigrae (SN) pathology seen in mitochondria, endoplasmic reticulum and neuromelanin (NM) is co-associated with the abundant presence of exogenous, Fe-, Al- and Ti-rich NPs.The SN exhibits early and progressive neurovascular unit damage and mitochondria and NM are associated with metal-rich NPs including exogenous engineered Ti-rich nanorods, also identified in neuroenteric neurons. Such reactive, cytotoxic and magnetic NPs may act as catalysts for reactive oxygen species formation, altered cell signaling, and protein misfolding, aggregation and fibril formation. Hence, pervasive, airborne and environmental, metal-rich and magnetic nanoparticles may be a common denominator for quadruple misfolded protein neurodegenerative pathologies affecting urbanites from earliest childhood. The substantia nigrae is a very early target and the gastrointestinal tract (and the neuroenteric system) key brainstem portals. The ultimate neural damage and neuropathology (Alzheimer's, Parkinson's and TDP-43 pathology included) could depend on NP characteristics and the differential access and targets achieved via their portals of entry. Thus where you live, what air pollutants you are exposed to, what you are inhaling and swallowing from the air you breathe,what you eat, how you travel, and your occupational longlife history are key. Control of NP sources becomes critical.

Future Perspectives on the Relevance of Auditory Markers in Prodromal Parkinson's Disease

Research on auditory processing in Parkinson's disease (PD) has recently made substantial progress. At present, evidence has been found for altered auditory processing in the clinical stage of PD. The auditory alterations in PD have been demonstrated with low-cost and non-invasive assessments that are already used in routine clinical practice. Since auditory alterations have been reported early in disease progression, it would be highly relevant to investigate whether auditory markers could be provided in the prodromal stage of PD. In addition, auditory alterations in early stage PD might be modulated by dopaminergic medication. Therefore, the aim of this review is (1) to summarize the literature on auditory processing in PD with a specific focus on the early disease stages, (2) to give future perspectives on which audiological and electrophysiological measurements could be useful in the prodromal stage of PD and (3) to assess the effect of dopaminergic medication on potential auditory markers in the prodromal stage of PD.

Alzheimer disease starts in childhood in polluted Metropolitan Mexico City. A major health crisis in progress

Exposures to fine particulate matter (PM_2.5) and ozone (O₃) above USEPA standards are associated with Alzheimer's disease (AD) risk. Metropolitan Mexico City (MMC) youth have life time exposures to PM_2.5 and O₃ above standards. We focused on MMC residents ≤30 years and reviewed 134 consecutive autopsies of subjects age 20.03 ± 6.38 y (range 11 months to 30 y), the staging of Htau and ß amyloid, the lifetime cumulative PM_2.5 (CPM _2.5) and the impact of the Apolipoprotein E (APOE) 4 allele, the most prevalent genetic risk for AD. We also reviewed the results of the Montreal Cognitive Assessment (MoCA) and the brainstem auditory evoked potentials (BAEPs) in clinically healthy young cohorts. Mobile sources, particularly from non-regulated diesel vehicles dominate the MMC pollutant emissions exposing the population to PM_2.5 concentrations above WHO and EPA standards. Iron-rich,magnetic, highly oxidative, combustion and friction-derived nanoparticles (CFDNPs) are measured in the brain of every MMC resident. Progressive development of Alzheimer starts in childhood and in 99.25% of 134 consecutive autopsies ≤30 years we can stage the disease and its progression; 66% of ≤30 years urbanites have cognitive impairment and involvement of the brainstem is reflected by auditory central dysfunction in every subject studied. The average age for dementia using MoCA is 20.6 ± 3.4 y. APOE4 vs 3 carriers have 1.26 higher odds of committing suicide. PM_2.5 and CFDNPs play a key role in the development of neuroinflammation and neurodegeneration in young urbanites. A serious health crisis is in progress with social, educational, judicial, economic and overall negative health impact for 25 million residents. Understanding the neural circuitry associated with the earliest cognitive and behavioral manifestations of AD is needed. Air pollution control should be prioritised-including the regulation of diesel vehicles- and the first two decades of life ought to be targeted for neuroprotective interventions. Defining paediatric environmental, nutritional, metabolic and genetic risk factor interactions is a multidisciplinary task of paramount importance to prevent Alzheimer's disease. Current and future generations are at risk.