Abstract
Current therapies for Alzheimer's disease do not modify the course of disease and are not universally beneficial. Clinical trials of drugs targeting amyloid and tau in established Alzheimer's disease have been unsuccessful as it is thought that treating established disease may be too late. Research has moved to the prodromal and pre-symptomatic phases of Alzheimer's disease, with a greater emphasis on the role of biomarkers in defining cases and monitoring response to therapy. Mixed pathologies predominate in the older population. The associations between biomarkers, neuropathology and clinical syndromes are weaker in older people and this is likely to pose a greater challenge in identifying effective therapies.