MicroRNA-Based Diagnosis and Therapeutics for Vascular Cognitive Impairment and Dementia

Neuropsychological aspects of reversible cerebral vasoconstriction syndrome

Despite the increasing knowledge in the past years, only minimal attention has been directed to the neuropsychological aspects and the prevalence of cognitive impairment associated with reversible cerebral vasoconstriction syndrome (RCVS).

Objective

To describe the frequency and expand the understanding of cognitive dysfunction in RCVS.

Methods

The neuropsychological evaluation was performed using a battery consisting of specific neuropsychological instruments that were administered to patients diagnosed with RCVS. A triage was conducted to exclude other potential causes of cognitive impairment. Performance on the tests was treated as a categorical variable, and a cutoff of -1.5 Z-score was adopted to indicate impaired performance.

Results

Seven patients diagnosed with RCVS were evaluated, all of whom had a bachelor's degree and normal score in the Mini-Mental State Examination. The average time between diagnosis and neuropsychological evaluation was 1.8 years. Among the patients, 85.6% (n=6) exhibited performance below that of the normal population in at least two of the administered tests. Specifically, 71.4% (n=5) showed alterations in tests from the Psychological Battery for Attention Assessment, with impairment observed in concentrated (n=1), divided (n=3), or alternating (n=4) attention. Furthermore, 28.6% (n=2) demonstrated impairments in the Phonological Verbal Fluency Task, another 28.6% (n=2) exhibited difficulties copying elements of the Rey Complex Figure, and 14.3% (n=1) displayed lower performance in the Five-Digit test, all indicating executive dysfunction.

Conclusion

This study provides evidence that cognitive impairment associated with RCVS is more prevalent than previously believed and has not received sufficient attention. Specifically, attention and executive functions are the cognitive domains most significantly impacted by RCVS.

Vascular dementia: From pathobiology to emerging perspectives

Vascular dementia (VaD) is the second most common type of dementia. VaD is synonymous with ageing, and its symptoms place a significant burden on the health and wellbeing of older people. Despite the identification of a substantial number of risk factors for VaD, the pathological mechanisms underpinning this disease remain to be fully elucidated. Consequently, a biogerontological imperative exists to highlight the modifiable lifestyle factors which can mitigate against the risk of developing VaD. This review will critically examine some of the factors which have been revealed to modulate VaD risk. The survey commences by providing an overview of the putative mechanisms which are associated with the pathobiology of VaD. Next, the factors which influence the risk of developing VaD are examined. Finally, emerging treatment avenues including epigenetics, the gut microbiome, and pro-longevity pharmaceuticals are discussed. By drawing this key evidence together, it is our hope that it can be used to inform future experimental investigations in this field.

Research progress on the association between MicroRNA and postoperative cognitive dysfunction

Postoperative cognitive dysfunction (POCD) is a significant complication following surgery. The precise mechanisms underlying POCD remain elusive, although it is speculated that they involve central nervous system inflammation, oxidative stress and cellular apoptosis. MicroRNAs (miRNAs), a class of non-coding RNAs widely distributed in eukaryotes, have been implicated in the pathogenesis of neurodegenerative disorders and could potentially impact POCD. This review explores the association between miRNAs and POCD and provides an overview of the progress of current research on miRNAs in the pathogenesis, diagnosis, and treatment of POCD.

Unraveling the Role of miR-200b-3p in Attention-Deficit/Hyperactivity Disorder (ADHD) and Its Therapeutic Potential in Spontaneously Hypertensive Rats (SHR)

Attention-deficit/hyperactivity disorder (ADHD) is a prevalent neurodevelopmental disorder in children with unknown etiology. Impaired learning ability was commonly reported in ADHD patients and has been associated with dopamine uptake in the striatum of an animal model. Another evidence also indicated that micro-RNA (miR)-200b-3p is associated with learning ability in various animal models. However, the association between miR-200b-3p and ADHD-related symptoms remains unclear. Therefore, the current study investigated the role of miR-200b-3p in ADHD-related symptoms such as inattention and striatal inflammatory cytokines. To verify the influence of miR-200b-3p in ADHD-related symptoms, striatal stereotaxic injection of miR-200b-3p antagomir (AT) was performed on spontaneously hypertensive rats (SHR). The antioxidant activity and expressions of miR-200b-3p, slit guidance ligand 2 (Slit2), and inflammatory cytokines in the striatum of SHR were measured using quantitative real-time polymerase chain reaction (RT-qPCR), immunohistochemistry (IHC), immunoblotting, and enzyme-linked immunosorbent assay (ELISA). The spontaneous alternation of SHR was tested using a three-arm Y-shaped maze. The administration of miR-200b-3p AT or taurine significantly decreased striatal tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6 in SHR, along with increased super-oxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities and significantly higher spontaneous alternation. In this paper, we show that miR-200b-3p AT and taurine alleviates ADHD-related symptoms in SHR. These findings provide insights into ADHD's molecular basis and suggest miR-200b-3p as a potential therapeutic target. Concurrently, this study also suggests broad implications for treating neurodevelopmental disorders affecting learning activity such as ADHD.

Gastrodin relieves cognitive impairment by regulating autophagy via PI3K/AKT signaling pathway in vascular dementia

Vascular dementia (VaD), the second most common type of dementia, is attributed to lower cerebral blood flow. To date, there is still no available clinical treatment for VaD. The phenolic glucoside gastrodin (GAS) is known for its neuroprotective effects, but the role and mechanisms of action on VD remains unclear. In this study, we aim to investigate the neuroprotective role and underlying mechanisms of GAS on chronic cerebral hypoperfusion (CCH)-mediated VaD rats and hypoxia-induced injury of HT22 cells. The study showed that GAS relieved learning and memory deficits, ameliorated hippocampus histological lesions in VaD rats. Additionally, GAS down-regulated LC3II/I, Beclin-1 levels and up-regulated P62 level in VaD rats and hypoxia-injured HT22 cells. Notably, GAS rescued the phosphorylation of PI3K/AKT pathway-related proteins expression, which regulates autophagy. Mechanistic studies verify that YP-740, a PI3K agonist, significantly resulted in inhibition of excessive autophagy and apoptosis with no significant differences were observed in the YP-740 and GAS co-treatment. Meantime, we found that LY294002, a PI3K inhibitor, substantially abolished GAS-mediated neuroprotection. These results revealed that the effects of GAS on VaD are related to stimulating PI3K/AKT pathway-mediated autophagy, suggesting a potentially beneficial therapeutic strategy for VaD.

MicroRNA (miRNA) Complexity in Alzheimer's Disease (AD)

AD is a complex, progressive, age-related neurodegenerative disorder representing the most common cause of senile dementia and neurological dysfunction in our elderly domestic population. The widely observed heterogeneity of AD is a reflection of the complexity of the AD process itself and the altered molecular-genetic mechanisms operating in the diseased human brain and CNS. One of the key players in this complex regulation of gene expression in human pathological neurobiology are microRNAs (miRNAs) that, through their actions, shape the transcriptome of brain cells that normally associate with very high rates of genetic activity, gene transcription and messenger RNA (mRNA) generation. The analysis of miRNA populations and the characterization of their abundance, speciation and complexity can further provide valuable clues to our molecular-genetic understanding of the AD process, especially in the sporadic forms of this common brain disorder. Current in-depth analyses of high-quality AD and age- and gender-matched control brain tissues are providing pathophysiological miRNA-based signatures of AD that can serve as a basis for expanding our mechanistic understanding of this disorder and the future design of miRNA- and related RNA-based therapeutics. This focused review will consolidate the findings from multiple laboratories as to which are the most abundant miRNA species, both free and exosome-bound in the human brain and CNS, which miRNA species appear to be the most prominently affected by the AD process and review recent developments and advancements in our understanding of the complexity of miRNA signaling in the hippocampal CA1 region of AD-affected brains.

MicroRNA Networks in Cognition and Dementia

The change from viewing noncoding RNA as “junk” in the genome to seeing it as a critical epigenetic regulator in almost every human condition or disease has forced a paradigm shift in biomedical and clinical research. Small and long noncoding RNA transcripts are now routinely evaluated as putative diagnostic or therapeutic agents. A prominent role for noncoding microRNAs in the central nervous system has uncovered promising new clinical candidates for dementia-related disorders, treatments for which currently remain elusive even as the percentage of diagnosed patients increases significantly. Cognitive decline is a core neurodegenerative process in Alzheimer’s Disease, Frontotemporal Dementia, Lewy body dementia, vascular dementia, Huntington’s Disease, Creutzfeldt–Jakob disease, and a significant portion of Parkinson’s Disease patients. This review will discuss the microRNA-associated networks which influence these pathologies, including inflammatory and viral-mediated pathways (such as the novel SARS-CoV-2 virus implicated in COVID-19), and their current status in clinical trials.