Looking at Alzheimer's Disease Pathogenesis from the Nuclear Side

Systematic review and meta-analysis of repetitive transcranial magnetic stimulation (rTMS) for activities of daily living in Alzheimer's disease

OBJECTIVE

This systematic review of randomised controlled trials (RCTs) was conducted to assess the effect of repetitive transcranial magnetic stimulation (rTMS) on activities of daily living (ADLs) in Alzheimer's disease (AD) patients.

DATA SOURCES

Ten databases were retrieved for pertinent Chinese and English literatures published up until January 2024.

REVIEW METHODS

All RCTs of rTMS for ADLs in AD were included in this meta-analysis. Two researchers independently selected the literatures, retrieved the data of included literatures, accessed risk-of-bias of literatures with the Cochrane Collaboration's quality criteria and then cross-checked. Meta-analysis was carried out with Cochrane's Review Manager (RevMan, version 5.4). The PRISMA guidelines were followed in this systematic review.

RESULTS

The 37 literatures involving 2461 patients with AD were included in this study. Compared with the control groups received the interventions such as routine pharmacotherapy, cognitive training, ect., with/without sham-rTMS, the experiment groups received the interventions of the control groups and rTMS. The findings were as follows: ADL scale [mean difference (MD) = -3.92, 95%CI (-4.93, -2.91), P < 0.00001]; Barthel Index (BI) [MD = 9.75, 95% CI (6.66, 12.85), P < 0.00001]; Modified Barthel Index (MBI) [MD = 5.43, 95% CI (3.13, 7.73), P < 0.00001]. The differences were statistically significant for all indicators. In 29 studies, rTMS stimulation sites were located in the dorsolateral prefrontal cortex (DLPFC).

CONCLUSION

The rTMS could improve the ADLs in AD patients, and the DLPFC was a frequently used stimulation site of the rTMS for AD treatment.

mTOR signaling and Alzheimer's disease: What we know and where we are?

Despite the great body of research done on Alzheimer's disease, the underlying mechanisms have not been vividly investigated. To date, the accumulation of amyloid-beta plaques and tau tangles constitutes the hallmark of the disease; however, dysregulation of the mammalian target of rapamycin (mTOR) seems to be significantly involved in the pathogenesis of the disease as well. mTOR, as a serine-threonine protein kinase, was previously known for controlling many cellular functions such as cell size, autophagy, and metabolism. In this regard, mammalian target of rapamycin complex 1 (mTORC1) may leave anti-aging impacts by robustly inhibiting autophagy, a mechanism that inhibits the accumulation of damaged protein aggregate and dysfunctional organelles. Formation and aggregation of neurofibrillary tangles and amyloid-beta plaques seem to be significantly regulated by mTOR signaling. Understanding the underlying mechanisms and connection between mTOR signaling and AD may suggest conducting clinical trials assessing the efficacy of rapamycin, as an mTOR inhibitor drug, in managing AD or may help develop other medications. In this literature review, we aim to elaborate mTOR signaling network mainly in the brain, point to gaps of knowledge, and define how and in which ways mTOR signaling can be connected with AD pathogenesis and symptoms.

Amyloid Precursor Protein: A Regulatory Hub in Alzheimer's Disease

Decades of research have demonstrated an incontrovertible role of amyloid-β (Aβ) in the etiology of Alzheimer's disease (AD). However, the overemphasis on the pathological impacts of Aβ may obscure the role of its metabolic precursor, amyloid precursor protein (APP), as a significant hub in the occurrence and progression of AD. The complicated enzymatic processing, ubiquitous receptor-like properties, and abundant expression of APP in the brain, as well as its close links with systemic metabolism, mitochondrial function and neuroinflammation, imply that APP plays multifaceted roles in AD. In this review, we briefly describe the evolutionarily conserved biological characteristics of APP, including its structure, functions and enzymatic processing. We also discuss the possible involvement of APP and its enzymatic metabolites in AD, both detrimental and beneficial. Finally, we describe pharmacological agents or genetic approaches with the capability to reduce APP expression or inhibit its cellular internalization, which can ameliorate multiple aspects of AD pathologies and halt disease progression. These approaches provide a basis for further drug development to combat this terrible disease.

Uncommon Noninvasive Biomarkers for the Evaluation and Monitoring of the Etiopathogenesis of Alzheimer's Disease

Background:

Alzheimer´s disease (AD) is the most widespread dementia in the world, followed by vascular dementia. Since AD is a heterogeneous disease that shows several varied phenotypes, it is not easy to make an accurate diagnosis, so it arises when the symptoms are clear and the disease is already very advanced. Therefore, it is important to find out biomarkers for AD early diagnosis that facilitate treatment or slow down the disease. Classic biomarkers are obtained from cerebrospinal fluid and plasma, along with brain imaging by positron emission tomography. Attempts have been made to discover uncommon biomarkers from other body fluids, which are addressed in this update.

Objective:

This update aims to describe recent biomarkers from minimally invasive body fluids for the patients, such as saliva, urine, eye fluid or tears.

Methods:

Biomarkers were determined in patients versus controls by single tandem mass spectrometry, and immunoassays. Metabolites were identified by nuclear magnetic resonance, and microRNAs with genome-wide high-throughput real-time polymerase chain reaction-based platforms.

Results:

Biomarkers from urine, saliva, and eye fluid were described, including peptides/proteins, metabolites, and some microRNAs. The association with AD neuroinflammation and neurodegeneration was analyzed, highlighting the contribution of matrix metalloproteinases, the immune system and microglia, as well as the vascular system.

Conclusion:

Unusual biomarkers have been developed, which distinguish each stage and progression of the disease, and are suitable for the early AD diagnosis. An outstanding relationship of biomarkers with neuroinflammation and neurodegeneration was assessed, clearing up concerns of the etiopathogenesis of AD.

Molecular Aspects of Cellular Dysfunction in Alzheimer's Disease: The Need for a Holistic View of the Early Pathogenesis

Alzheimer's disease (AD) is the most common cause of dementia in the elderly, a socio-economic burden destined to worsen with increased population aging [...].