Current Alzheimer Research - Volume 22, Issue 2, 2025

Type 2 Diabetes Mellitus (T2D) and Alzheimer's disease (AD) are two diseases with a high prevalence today that share common pathophysiological mechanisms, suggesting a potential causal relationship between them. AD is also known as Type 3 Diabetes Mellitus (T3D). A complete understanding of this complex issue (T2D-AD) is necessary to develop fully effective and easily applicable therapies that do not yet exist. A critical update on the subject is presented, delving into the pathophysiological implications and defining new research for promoting new therapeutic interventions.

Revision and critical analysis of the described and observed cellular and molecular common pathogenic T2D-AD mechanisms in human and model studies.

Both diseases exhibit common genetic, epigenetic, biochemical and physiological characteristics. Pathogenic mechanisms such as peripheral inflammation, mitochondrial dysfunction, oxidative stress, insulin resistance, hyperglycemia, formation of advanced glycation end products, neuroinflammation, neuroglial dysfunctions, and deposition of aberrant misfolded proteins are commonly displayed in dysmetabolic diseases and AD. The T2D, AD and T2D-AD pathogenic courses present several close key contacts (or identities). The clinical course of T2D has different incidence in the neurodegenerative course of AD (from its onset to its aggravation). There are theoretical, practical and interpretative problems in studies on human and experimental models, as well as in the clinical and pathological interpretation of T2D-AD dementia, which are of great importance in the development of knowledge of this subject and the therapeutic application of its results.

In recent years, there has been a great advance in the study of the relationships between T2D (and related dysmetabolic diseases) and AD. There is no doubt about their close relationship and/or the inclusion of AD as a metabolic disease (T3D). Joint therapies seem to be absolutely necessary. Key pathogenic processes (insulin resistance, genetic and epigenetic regulation, peripheral inflammation and neuroinflammation) must be investigated to develop new and effective therapies.

Prolonged or repeated psychological stress triggers dental and orthodontic diseases via inflammatory pathways and oxidative stress. This review aims to elucidate the role of inflammation, gut microbiota, stress, and cognition, exploring their impact on the development of therapeutics to enhance oral health.

The primary aim pertinent to this systematic review is to elucidate the significant implications of cognition and stress in dental and orthodontic health. Specifically, the review aims to (1) investigate the association between emotional stress and the incidence or progression of periodontal disease; (2) explore the impact of physiological and emotional stress on cellular and molecular inflammatory responses in orthodontics; (3) examine the influence of gut-mediated psychophysiological factors on emotional changes in mental health and cognition with a focus on periodontics and orthodontics; and (4) investigate the potential of gut microbiota alterations to influence oral and cognitive/mental health, including the impact of probiotic supplementation and dietary interventions.

A systematic review was conducted without comprehensive meta-analysis, focusing on literature from 1960 to 2024. Databases searched included PubMed, Embase, ReleMed, National Library of Medicine (NLM), Scopus, and Google Scholar. Keywords used were “cognition,” “emotional stress,” “gut microbiota,” “orthodontics,” “prosthetics,” “pathophysiology,” and “mental health.” Studies were selected based on relevance, publication date, access to full texts, and adherence to PRISMA guidelines. The review integrated findings on the impact of emotional stress on periodontal disease and orthodontic health through pathophysiological implications.

Age-related neurodegeneration causes Alzheimer’s disease and severe dementia that subsequently promotes poor oral health. The review identified a complex interplay between emotional stress and periodontal disease. While a direct association remains to be conclusively proven, several studies highlight the influence of stress on the severity and incidence of periodontal disease through inflammatory and immunological pathways. Stress manifests in various ways, such as increased masticatory muscle tone, changes in eating behavior, and the initiation of bruxism, all of which can affect dental health. Physiological stress induces an inflammatory response to orthodontic tooth movement, impacting orthodontic treatment outcomes. Furthermore, the review elucidates the role of gut-mediated psychophysiological factors in emotional changes, influencing periodontal and orthodontic health. Emerging evidence suggests that gut microbiota alterations can significantly impact oral and cognitive health through systemic inflammation and neuroimmune mechanisms.

This review highlights the significant impact of physiological and emotional stress on periodontal and orthodontic health. Detailed exploration of cellular and molecular inflammatory responses provides insights into the pathophysiology of orthodontic diseases and their impact on oral health. Gut-brain-oral axis has significance in oral health, exploring how alterations in gut microbiota influence oral and cognitive health. It is essential to investigate the impact of probiotic supplementation and dietary modifications on gut microbiota composition, systemic inflammation, and their influence on both cognitive and oral health. Clinical trials assessing the effectiveness of anti-inflammatory treatments in reducing periodontal disease and cognitive decline could offer valuable insights. Integrating advanced microbiome analysis techniques and neuroimaging can help clarify the mechanisms linking gut health, systemic inflammation, and cognitive function. Exploring specific gut microbiota strains that regulate systemic inflammation and cognitive function may lead to targeted probiotic therapies, potentially alleviating neuroinflammation and enhancing cognitive performance. Additionally, understanding the role of oral probiotics in periodontal health and their effects on gut microbiota and systemic inflammation could contribute to the development of innovative treatment approaches. This knowledge can aid molecular biologists, dentists, and researchers in managing oral and gut health more effectively.

This study aims to investigate the molecular mechanisms underlying Alzheimer’s disease (AD) by analyzing differentially expressed miRNAs and their target proteins to identify key regulatory networks and therapeutic targets.

Alzheimer’s disease (AD) is a complex neurodegenerative disorder with multifaceted regulatory mechanisms involving differentially expressed miRNAs. Recent studies suggest that understanding the target proteins of these miRNAs may reveal crucial insights into AD pathology.

The objective of this study was to investigate the role of differentially expressed miRNAs in Alzheimer’s disease (AD) by identifying their target proteins and exploring the associated regulatory networks. This includes uncovering key hub proteins and their involvement in critical biological pathways linked to AD progression. Additionally, the study aims to identify transcription factors regulating these proteins and evaluate potential therapeutic compounds targeting these molecular players. By integrating these findings, the research seeks to provide a deeper understanding of AD pathogenesis and pave the way for novel therapeutic strategies to mitigate its progression.

Differentially expressed miRNAs were collected from reviews, with target proteins identified using MiRDB, STRING, and Cytoscape. Promoter and transcription factor (TF) analyses were performed using Enrichr, and potential therapeutic compounds targeting hub proteins were explored via DrugBank.

This study identifies key hub proteins, including TNF, PTEN, KRAS, ESR1, H3-3B, COL25A1, COL19A1, COL13A1, COL27A1, COL5A3, CCND1, FGF2, SMAD2, and PXDN, exploring their roles in AD progression. GO and KEGG pathway analyses revealed that hub proteins, including TNF, PTEN, KRAS, and ESR1, are involved in essential biological processes related to neural differentiation and signaling. Cytocluster analysis identified clusters with significant associations with AD, indicating complex interaction networks among these proteins.

Potential therapeutic agents, including TNF inhibitors, estrogen receptor agonists, and KRAS inhibitors, were identified. Promoter and TF analysis further highlighted regulatory factors in AD pathways.

This study emphasizes crucial AD-related proteins and pathways, providing insights for future therapeutic targeting of gene expression to mitigate AD progression.