Fig. 1

The infection hypothesis of Alzheimer’s disease (AD). Ageing processes leading to increased risks of AD are shown in green. Pathogenic viruses, bacteria, fungi, and parasites potentially associated with AD are shown in grey. Molecular components of pathogenic agents, e.g., DNA, RNA, capsid proteins, proteolytic enzymes, peptidoglycans, and lipopolysaccharides potentially present in biological samples of AD subjects are shown in blue. Two known hallmarks of the disease—Aβ fibrils and Tau tangles—are depicted using red and blue cartoons. Brain tissue, both healthy and degenerated, is represented by yellow cartoons