Emerging evidence suggests that chronic infections may contribute to neurodegenerative diseases such as Alzheimer's disease (AD). One such infection is caused by Borrelia burgdorferi sensu lato (Bbsl), the spirochete complex responsible for Lyme disease, which can invade the central nervous system (CNS) and trigger Lyme neuroborreliosis (LNB). Bbsl infection is associated with persistent neuroinflammatory responses and immune evasion mechanisms, which may contribute to long-term neurological sequelae in a subset of patients. Neuroinflammation is increasingly recognized as a contributing factor in AD pathogenesis. This review examines proposed mechanistic overlaps between LNB and AD, focusing on the role of Bbsl-induced neuroinflammation driving amyloid-beta (Aβ) accumulation and tau pathology. We summarize evidence from in vitro, in vivo, and postmortem studies reporting assay-dependent co-localization of Borrelia with hallmark AD pathology in selected cases, alongside epidemiological studies that yield mixed results. While some studies suggest an association between Bbsl exposure and neurodegenerative risk, others report no clear correlation. Overall, current evidence indicates only an association, and a causal relationship between Bbsl infection and AD has not been established. Understanding this potential link may inform future mechanistic studies, biomarker development, and preventive strategies targeting chronic infection-driven neuroinflammation to address the hypothesis.
Ahuja et al. (2026) studied this question.