As Markku Toivonen, MD, PhD, chairman of CHMP Scientific Advice Working Party, explains in this piece, according to current evidence, Alzheimer’s disease (AD) is a disease continuum with a 10-20-year pre-symptomatic phase preceding the onset of dementia. The International Working Group (IWG) on research diagnostic criteria for AD provided in 2007 a new framework, where the presence of biomarkers characteristic of AD, albeit not mandatory for diagnosis, provides additional proof of diagnosis in the absence of clear clinical manifestations.