Relationship between Alzheimer's Disease and Type 2 Diabetes: Critical Review On Cellular and Molecular Common Pathogenic Mechanisms

Abstract

Background: 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. Methods: Revision and critical analysis of the described and observed cellular and molecular common pathogenic T2D-AD mechanisms in human and model studies. Results: 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 incidences 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. Conclusion: 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.