Peripheral Insulin Resistance and Alzheimer's Disease: Possible Mediators Including Extracellular Vesicles

Area of Science:

• Neuroscience
• Metabolic Disorders
• Epidemiology

Background:

• Type 2 diabetes mellitus (T2DM) is a known risk factor for Alzheimer's disease (AD).
• Insulin resistance, a hallmark of T2DM, is implicated as a key metabolic driver of AD pathogenesis, potentially preceding or exacerbating neurodegeneration.
• Existing research suggests insulin resistance is linked to amyloid-beta (Aβ) accumulation but has inconsistent findings regarding tau pathology.

Purpose of the Study:

• To review epidemiological and experimental evidence connecting peripheral insulin resistance to Alzheimer's disease.
• To explore the potential role of extracellular vesicles in mediating the communication between peripheral insulin resistance and brain pathology in AD.

Main Methods:

• Review of epidemiological studies linking T2DM and AD.
• Analysis of experimental and animal model data investigating insulin resistance and brain function.
• Examination of emerging evidence on extracellular vesicle function in inter-tissue communication.

Main Results:

• Consistent epidemiological data link T2DM to increased AD risk.
• Insulin resistance, particularly peripheral, is strongly associated with earlier Aβ accumulation and cognitive decline in AD.
• Animal studies support insulin resistance's independent role in cognitive and behavioral deficits, distinct from central insulin signaling disruption.

Conclusions:

• Peripheral insulin resistance is a significant factor contributing to brain vulnerability in Alzheimer's disease.
• The precise mechanisms by which peripheral insulin resistance affects the brain are still under investigation.
• Extracellular vesicles are emerging as a potential pathway for peripheral-central communication in the context of insulin resistance and AD.