Degradation of plastic-containing products, including food and beverage containers, clothing, construction materials, and rubber tires, occurs when the semicrystalline polymers comprising the majority of commercial plastics accumulate chain scission events resulting from abrasion, shear stress, and UV/heat exposure. These deteriorating polymers produce micro- and nanoplastics, the latter of which is represented in the electron microscopy image. Inhalation of airborne nanoplastic particles and ingestion of nanoplastics in food and beverages are two routes of entry into the human body, where nanoplastics have been identified in nearly every tissue, including in the brain. The presence of nanoplastics in brain tissue is linked to pro-inflammatory states and aggregation of proteins such as α-synuclein, amyloid-β, and tau that propagate in neurodegenerative diseases. Notably, the size and lipid-like biophysical properties of nanoplastics are conducive to pathological interactions with these proteins. Red question marks highlight priorities for future investigations of nanoplastic reservoirs in the brain.