Bart De Strooper, MD, PhD, UK Dementia Research Institute and University College London, London, UK, discusses how Alzheimer’s disease is defined. Currently, in the clinic, Alzheimer’s disease is only diagnosed in the presence of dementia. However, the original biological definition is characterized by the presence of amyloid plaques and tau tangles. The presence of these plaques and tangles used to be only identified postmortem, however, now they can be identified via blood markers and PET scans. Although, clinicians do not see the value of diagnosing patients with Alzheimer’s without dementia due to the lack of treatment. Nevertheless, early identification of Alzheimer’s patients would be beneficial in research and clinical trials. This interview took place during the Virtual World Congress on Controversies in Neurology (CONy) 2020.