A new paper by the European Prevention of Alzheimer’s Dementia (EPAD) initiative entitled "European Prevention of Alzheimer’s Dementia Longitudinal Cohort Study (EPAD LCS): study protocol" has been published online. EPAD is conducting a Longitudinal Cohort Study (LCS) in alignment with an adaptive designed EPAD Proof-of-Concept (PoC) trial. This article presents the EPAD LCS study protocol including its objectives, design, methods and outcomes. The article was published in the journal BMJ Open on 27 December 2018. The EPAD project has received support from the Innovative Medicines Initiative Joint Undertaking under grant agreement n° 115736, resources of which are composed of financial contribution from the European Union's Seventh Framework Programme (FP7/2007-2013) and EFPIA companies’ in kind contribution.