An aging, pathology burden, and glial senescence build-up hypothesis for late onset Alzheimer's disease

Alzheimer's disease (AD) predominantly occurs as a late onset (LOAD) form involving neurodegeneration and cognitive decline with progressive memory loss. Risk factors that include aging promote accumulation of AD pathologies, such as amyloid-beta and tau aggregates, as well as inflammation and oxidative stress. Homeostatic glial states regulate and suppress pathology buildup; inflammatory states exacerbate pathology by releasing pro-inflammatory cytokines. Multiple stresses likely induce glial senescence, which could decrease supportive functions and reinforce inflammation. In this perspective, we hypothesize that aging first drives AD pathology burden, whereafter AD pathology putatively induces glial senescence in LOAD. We hypothesize that increasing glial senescence, particularly local senescent microglia accumulation, sustains and drives perpetuating buildup and spread of AD pathologies, glial aging, and further senescence. We predict that increasing glial senescence, particularly local senescent microglia accumulation, also transitions individuals from healthy cognition into mild cognitive impairment and LOAD diagnosis. These pathophysiological underpinnings may centrally contribute to LOAD onset, but require further mechanistic investigation. In this perspective, the authors hypothesise that glial senescence, requiring senescent microglia burden, perpetuates further aging, Alzheimer's pathologies, and senescence. Increasing glial senescence is proposed as necessary to drive individuals from healthy cognition into cognitive decline and dementia.

Automated summary

Alzheimer's disease primarily involves neurodegeneration and cognitive decline, with progressive memory loss. Aging and other risk factors promote the accumulation of AD pathologies and inflammation. Glial senescence, particularly senescent microglia accumulation, contributes to the perpetuation of AD pathologies, glial aging, and further senescence. Increasing glial senescence is proposed to drive individuals from healthy cognition into cognitive decline and dementia.