Current Alzheimer Research - Volume 21, Issue 1, 2024

Background: As modern medicine continues to make strides in effective surgical treatments, we must also consider the critical impact of anesthesia on neuropsychological outcomes. Recent evidence suggests that anesthesia exposure may be a risk factor for postoperative cognitive decline and the eventual development of dementia. Objectives: To explore the vulnerability of the aging brain in the context of anesthesia exposure in surgery, studies will be reviewed, and pertinent findings will be highlighted and explored to better understand risks and possible factors that need to be considered when contemplating surgery. Methods: A narrative review was conducted using a combination of MEDLINE and APA PsycINFO databases to shed light on themes across studies assessing general trends regarding the influence of anesthesia on postoperative cognitive decline. Results: A search of relevant literature identified 388 articles. Excluding results outside the parameters of this study, the review includes quality assessments for 24 articles. Conclusion: While findings are inconclusive, suggestions for further investigation into the relationship between anesthesia exposure and increased risk for postoperative cognitive decline are discussed, in addition to factors that may allow for greater informed disclosure of potential risks of anesthesia in older adults.

Microtubule-Associated Protein Tau (also known as tau) has been shown to accumulate into paired helical filaments and neurofibrillary tangles, which are known hallmarks of Alzheimer's disease (AD) pathology. Decades of research have shown that tau protein undergoes extensive post-translational modifications (PTMs), which can alter the protein's structure, function, and dynamics and impact the various properties such as solubility, aggregation, localization, and homeostasis. There is a vast amount of information describing the impact and role of different PTMs in AD pathology and neuroprotection. However, the complex interplay between these PTMs remains elusive. Therefore, in this review, we aim to comprehend the key post-translational modifications occurring in tau and summarize potential connections to clarify their impact on the physiology and pathophysiology of tau. Further, we describe how different computational modeling methods have helped in understanding the impact of PTMs on the structure and functions of the tau protein. Finally, we highlight the tau PTM-related therapeutics strategies that are explored for the development of AD therapy.

Acetylcholine (ACh) is ubiquitously present in the nervous system and has been involved in the regulation of various brain functions. By modulating synaptic transmission and promoting synaptic plasticity, particularly in the hippocampus and cortex, ACh plays a pivotal role in the regulation of learning and memory. These procognitive actions of ACh are mediated by the neuronal muscarinic and nicotinic cholinergic receptors. The impairment of cholinergic transmission leads to cognitive decline associated with aging and dementia. Therefore, the cholinergic system has been of prime focus when concerned with Alzheimer's disease (AD), the most common cause of dementia. In AD, the extensive destruction of cholinergic neurons occurs by amyloid-β plaques and tau protein-rich neurofibrillary tangles. Amyloid-β also blocks cholinergic receptors and obstructs neuronal signaling. This makes the central cholinergic system an important target for the development of drugs for AD. In fact, centrally acting cholinesterase inhibitors like donepezil and rivastigmine are approved for the treatment of AD, although the outcome is not satisfactory. Therefore, identification of specific subtypes of cholinergic receptors involved in the pathogenesis of AD is essential to develop future drugs. Also, the identification of endogenous rescue mechanisms to the cholinergic system can pave the way for new drug development. In this article, we discussed the neuroanatomy of the central cholinergic system. Further, various subtypes of muscarinic and nicotinic receptors involved in the cognition and pathophysiology of AD are described in detail. The article also reviewed primary neurotransmitters that regulate cognitive processes by modulating basal forebrain cholinergic projection neurons.

Background: A plethora of studies has shown the utility of several chemical dyes due to their affinity to bind Aβ to enable visualization of plaques under light or fluorescence microscope, and some of them showed affinity to bind neurofibrillary tangles (NFT) as well. However, only a few of them have the propensity to bind both senile plaques (SP) and NFT simultaneously. Objective: In our current study, we aimed to modify the K114 dye and the staining procedure to substantially improve the staining of amyloid plaques in both human and rodent brains and neurofibrillary tangles in the human brain. Methods: We modified the K114 solution and the staining procedure using Sudan Black as a modifier. Additionally, to evaluate the target of the modified K114, we performed double labeling of K114 and increased Aβ against three different epitopes. We used 5 different antibodies to detect phosphorylated tau to understand the specific targets that modified K114 binds. Results: Dual labeling using hyperphosphorylated antibodies against AT8, pTau, and TNT1 revealed that more than 80% hyperphosphorylated tau colocalized with tangles that were positive for modified K114, whereas more than 70% of the hyperphosphorylated tau colocalized with modified K114. On the other hand, more than 80% of the plaques that were stained with Aβ MOAB-2 were colocalized with modified K114. Conclusion: Our modified method can label amyloid plaques within 5 min in the rat brain and within 20 min in the human brain. Our results indicated that modified K114 could be used as a valuable tool for detecting amyloid plaques and tangles with high contrast and resolution relative to other conventional fluorescence markers.

Background: As the cholinesterase theory is a prominent hypothesis underlying our current understanding of Alzheimer's disease (AD), the goal of this study was to compose functional vegan lunchtime soups with potential health benefits in the prevention of AD (in the context of cholinesterase inhibition). Materials and Methods: The potential of 36 edible plant raw materials in terms of acetyl- and butyrylcholinesterase inhibition was investigated using a 96-well microplate reader. The most promising ingredients were combined to obtain 18 palatable vegetable soup recipes with 6 dominant flavor, appearance, and aroma variants. To shortlist candidates for in-depth analysis and potential consideration in industrial production, our team performed a sensory analysis of the soups. Results: The white boletus soup exhibited the highest potential for cholinesterase inhibition, further bolstered by the inclusion of other ingredients known for their elevated capacity to inhibit both AChE and BChE. Ingredients such as blackthorn (Prunus spinosa), garlic, and white potato contributed significantly to this inhibitory effect (nearly 100% of AChE inhibition). Notably, intriguing results were also observed for asparagus soup, despite the fact that the inhibitory potential of asparagus itself is negligible compared to other raw materials. The success of the asparagus soup lies in the meticulous selection of various ingredients, each contributing to its overall effectiveness. It was observed that mushroom soups scored the highest in this respect, while the team members’ response to nettle soup was the least favorable. Conclusion: The outcomes of our study should serve as a catalyst for further exploration of this important research domain. Our current research focuses on deeper insights into the potential of comprehensive meal options. Furthermore, the synergy/antagonism/non-interaction between respective soup ingredients as well as elements of individual soups’ chemical composition is a very interesting topic currently under our intensive scientific investigation.