The accumulation of polystyrene nanoplastics leads to increased levels of amyloid-β (Aβ) and phosphorylated Tau protein (P-Tau) in the cerebral cortex and hippocampus, which are metabolic waste products associated with neurobehavioral disorders and neurodegenerative diseases such as Alzheimer’s disease. Here, MAPT is linked to early-onset autosomal dominant Alzheimer disease.