Regional wasteosome accumulation across neurodegenerative diseases points to a shared underlying mechanism potentially related to glymphatic insufficiency.

The glymphatic system plays a key role in clearing waste products from the brain and is essential for maintaining brain homeostasis. When dysfunctional, it appears to contribute to pathological changes that exacerbate brain disorders, including neurodegenerative diseases. Additionally, wasteosomes, also known as corpora amylacea, are structures that function as waste containers and are thought to increase in response to chronic glymphatic insufficiency. Hence, in this study, we evaluated whether the accumulation and distribution of wasteosomes are compatible with both the potential role of wasteosomes as a hallmark of the chronic glymphatic insufficiency and the presence of this insufficiency in certain neurodegenerative diseases. Accordingly, brain tissue from 185 donors was analysed, including cases of Alzheimer's disease, amyotrophic lateral sclerosis with TDP-43 proteinopathy, frontotemporal lobar degeneration with TDP-43 or tau proteinopathy, and non-diseased controls. Wasteosomes were examined across 28 brain regions comprised within 5 major brain areas, using region-specific scoring systems. Analysis was conducted through variance and covariance analyses, along with decision tree procedures. The findings reveal that wasteosomes are consistently found in specific critical regions, with a higher burden in donors with neurodegenerative diseases compared with controls. These regions are independent of the regional distribution of the underlying proteinopathy, and are potentially associated with glymphatic drainage pathways. From an integrated perspective, although further studies are required, the increased presence of wasteosomes in these critical regions across all diseased groups is consistent with the potential presence of chronic glymphatic insufficiency in these diseases.