Unmasking the hidden catalyst: How infections trigger Alzheimer's disease

For years, the understanding of Alzheimer's disease (AD) has been shaped by the amyloid hypothesis, which suggests that pathological markers like amyloid-β (Aβ) and phosphorylated tau are the primary drivers of the disease. This hypothesis has guided the development of major treatment strategies, including monoclonal antibodies targeting Aβ. However, most of these treatments have failed to produce clinically significant results, highlighting the urgent need for a new therapeutic approach. It is now evident that AD is a complex, multifactorial disease that develops over decades, ultimately leading to Aβ and tau accumulation. Therefore, addressing the underlying causes of these depositions is crucial. One well-supported yet underrecognized theory is the infection hypothesis, which links infections to AD pathology. Despite substantial scientific evidence, this perspective has faced significant resistance. In this review, we describe how chronic infections contribute to AD by triggering neuroinflammation and Aβ accumulation. We also explore the barriers to accepting the infection hypothesis and the steps necessary for its integration into drug development and early-stage treatment strategies. Persisting with an amyloid-centric approach will only exacerbate the societal burden. Embracing the infection hypothesis could transform AD research, diagnosis, and treatment, bringing new hope to millions.