Microplastics detection in freshly harvested human brain tissues of northeast Chinese postmortem donors and their correlation with Alzheimer's disease- related pathological proteins.

Microplastics (MPs) and nanoplastics (NPs) (MNPs) have been linked to various health risks, but their presence in the human brain and association with Alzheimer's disease (AD)-related pathological proteins remain poorly understood. In this study, superior temporal gyrus tissues of 16 northeast Chinese postmortem donors were analyzed via pyrolysis-gas chromatography-mass spectrometry (Py-GC/MS) and laser direct infrared spectroscopy (LDIR) to characterize MNPs, while AD-related pathological proteins Aβ and p-tau levels in the hippocampus were detected by immunohistochemical staining and quantified by H-score. Py-GC/MS quantification revealed polymers corresponding to polyethylene (PE), polyvinyl chloride (PVC), polystyrene (PS) and polypropylene (PP) in all samples, with PE as the dominant type (63.3% of total polymers concentrations). The overall mean concentration of these four polymers was 105.70μg/g ranging from 24.69μg/g to 184.77μg/g. LDIR of four selected samples further identified 17 additional types of MPs besides the aforementioned four; additionally, 80.8% of MPs had diameters smaller than 60 μm, and 84.7% were spherical and irregular in shape. Exploratory multiple linear regression suggested positive associations of PE and PS with Aβ levels. This study provided evidence of plastic polymers in fresh human brain tissue and established a preliminary association between polymers burden and AD-related pathological proteins, might provide a valuable basis for future studies investigating the association between MNPs and AD.