For the first time, researchers have found higher levels of Gram-negative bacteria antigens in brain samples from late-onset Alzheimer’s disease patients. Compared to controls, patients with Alzheimer's had much higher levels of lipopolysaccharide (LPS) and E coli K99 pili protein. In addition, the research team also found LPS molecules congregated with amyloid plaques, which have been linked to Alzheimer’s pathology and progression.