Cerebral hypoperfusion reduces tau accumulation.

Abstract

Objective: Alzheimer's disease (AD) often coexists with cerebrovascular diseases. However, the impact of cerebrovascular diseases such as stroke on AD pathology remains poorly understood.

Methods: This study examines the correlation between cerebrovascular diseases and AD pathology. The research was carried out using clinical and neuropathological data collected from the National Alzheimer's Coordinating Center (NACC) database and an animal model in which bilateral common carotid artery stenosis surgery was performed, following the injection of tau seeds into the brains of wild-type mice.

Results: Analysis of the NACC database suggests that clinical stroke history and lacunar infarcts are associated with lower neurofibrillary tangle pathology. An animal model demonstrates that chronic cerebral hypoperfusion reduces tau pathology, which was observed in not only neurons but also astrocytes, microglia, and oligodendrocytes. Furthermore, we found that astrocytes and microglia were activated in response to tau pathology and chronic cerebral hypoperfusion. Additionally, cerebral hypoperfusion increased a lysosomal enzyme, cathepsin D.

Interpretation: These data together indicate that cerebral hypoperfusion reduces tau accumulation likely through an increase in microglial phagocytic activity towards tau and an elevation in degradation through cathepsin D. This study contributes to understanding the relationship between tau pathology and cerebrovascular diseases in older people with multimorbidity.