Parkinson's disease (PD) and dementia have risen markedly in many regions. While aging, genetics, toxicants, and protein misfolding explain key aspects of pathology, they do not fully account for synchronized temporal trends or pronounced regional heterogeneity in recent increases. This hypothesis and theory article proposes that persistent microorganisms in industrial food systems-particularly biofilm-forming spirochetes in high-throughput poultry processing-may represent an under-recognized upstream contributor via the gut-brain axis. Analysis of Global Burden of Disease and FAOSTAT data reveals a population-level temporal alignment between rising PD incidence and poultry consumption in the United States and China, with a multi-year lag consistent with prodromal disease phases. In contrast, countries with differing sanitation and feed-chain policies (e.g., Israel's kosher salting and Germany's oxidative/thermal methods) show more stable neurodegenerative trends despite high poultry intake. These patterns suggest that sanitation chemistry, processing throughput, and animal-protein recycling may influence long-term microbial exposure risk. The proposed model integrates infection, gut-brain signaling, and protein-misfolding pathways by positioning chronic microbial persistence as a plausible initiating or amplifying factor. Supporting observations include spirochete detection in neurodegenerative tissue, biofilm adaptation under disinfection stress, and experimental evidence linking intestinal bacteria to α-synuclein pathology. Testable predictions include detection of resilient spirochetes or related taxa in post-sanitation products and higher microbial signatures in relevant patient samples.