The research alliance group REGG is part of the "Gerontopole Brussels", an interdisciplinary research consortium that brings together 10 research groups (REGG + 9 VUB research groups) that work in the field of Gerontology. The Gerontopole Brussels conducts an interdisciplinary research program with the central theme "Active and Healthy Aging". The Gerontopole Brussels benefits from IRP program financing from the VUB (+/- 100k € / year). A large - scale cohort study is currently underway within the Gerontopole Brussels consortium: the BUTTERFLY study (BrUssels sTudy on The Early pRedictors of FraiLtY: identification of determinants for active and healthy aging and for early stages of frailty in the oldest old). This cohort study focuses on identifying early predictors of vulnerability in older people living at home above the age of 80. At present more than 190 people aged 80 year or more have already been recruited who have been monitored for 2 years.