In the course of Alzheimer's disease, two proteins called 'amyloid' and 'tau' accumulate in the brain. A new study with more than 200 participants now provides insights into the interaction of these pathological phenomena. The data suggest that tau load in the brain impairs memory functions only when amyloid burden is also high. These findings therefore support therapeutic approaches aimed at removing amyloid from the brain in the early stages of Alzheimer's disease.