A genetic variation in some people may be associated with cognitive decline that can’t be explained by deposits of two key proteins associated with Alzheimer’s disease, amyloid ß and tau, according to a study published in the September 16, 2020, online issue of Neurology®, the medical journal of the American Academy of Neurology. The genetic variation leads to alterations in the metabolism of glutathione, an antioxidant, and may be associated with thinning of the cortex of the brain, the study says. The variation is found on the sixth chromosome.