Oskar Fischer and Alois Alzheimer first suggested a possible link to infections in 1907. Various infectious agents, including viruses, bacteria, spirochetes, fungi, and prions, have been implicated in its etiology. However, the role of these pathogens in AD is complex and intertwined with numerous other factors.nInfections may contribute to AD through several mechanisms. When an infectious agent invades the body, the host’s immune response produces a range of chemicals and proteins that can impact the brain. Additionally, the stress response, environmental factors, and treatments can all interact with infectious agents to influence disease progression. Several pathogens have been specifically studied for their potential role in AD. Fungal infections have also been proposed as a contributing factor. Despite these findings, establishing a clear causative role for infections in AD remains challenging. The interactions between infections and other risk factors highlight the complexity of AD etiology, underscoring the need for comprehensive approaches in both research and treatment to address this debilitating condition. This section discusses the role of infectious agents in the pathogenesis of Alzheimer’s disease.