Arsenic Exposure Linked to Alzheimer's-like Brain Cell Changes

Alzheimer's disease (AD) is a devastating neurodegenerative disorder characterized by the accumulation of amyloid-beta (Aβ) plaques in the brain. While genetic factors play a role, environmental toxins are increasingly recognized as potential contributors to AD pathology. Despite growing evidence, the precise mechanisms by which environmental heavy metals like arsenic influence Aβ metabolism and aggregation remain poorly understood.

The study revealed that arsenic exposure significantly altered key pathways involved in Aβ metabolism. Intracellular Aβ(1-42) accumulation was markedly increased, with cells exposed to 2.5 µM sodium arsenite showing a 2.8-fold increase compared to untreated controls (p<0.001). This accumulation was attributed to a dual mechanism: an 85% increase in APP expression (a protein from which Aβ is cleaved) and a 40% reduction in NEP (a key Aβ-degrading enzyme) expression at the 2.5 µM dose (p<0.01). The most striking finding was that arsenic indirectly stimulated extracellular Aβ aggregation, demonstrating a 3.2-fold increase in aggregated Aβ after 48 hours of exposure, largely mediated by a 60% induction of AChE activity (p<0.001). This suggests a complex interplay where arsenic not only boosts Aβ production and reduces its clearance but also promotes its clumping outside cells.