Giancarlo Logroscino, MD, PhD, Università degli Studi di Bari, Bari, Italy, discusses the reconstructed cohort design to examine rare neurodegenerative diseases. By using this approach diseases that are hard to track due to their low incidence, can be monitored and represent real-world data. This will help improve our understanding of the biology of rare diseases in what was an exhausted collection of data. This interview took place during the Virtual World Congress on Controversies in Neurology (CONy) 2020.