The PREVENT dementia programme: baseline demographic, lifestyle, imaging and cognitive data from a midlife cohort study investigating risk factors for dementia by Ritchie, CW, Bridgeman, K, Gregory, S, O’Brien, JT, Danso, SO, Dounavi, M, Carriere, I, Driscoll, D, Hillary, R, Koychev, I, Lawlor, B, Naci, L, Su, L, Low, A, Mak, E, Malhotra, P, Manson, J, Marioni, R, Murphy, L, Ntailianis, G, Stewart, W, Muniz-Terrera, G, Ritchie, K