Researchers have identified an enzyme that could halt or possibly even reverse the build-up of toxic protein fragments known as plaques in the brains of mice with Alzheimer’s disease. Plaques decreased substantially in mice treated with gene therapy to increase activity of the enzyme neuraminidase 1 (NEU1) in a region of the brain involved in learning and memory. NEU1 belongs to a family of enzymes in cells whose job is to dismantle and recycle unneeded proteins and other components. The enzyme is missing or reduced in a rare inherited disorder called sialidosis that can affect children and adolescents. The work was done in