Mental Health in UK Biobank – implementation and results of an online questionnaire in 157,366 participants by Davis, KAS, Coleman, JRI, Adams, M, Allen, NE, Breen, G, Cullen, B, Dickens, C, Fox, EMM, Graham, N, Holliday, J, Howard, LM, John, A, Lee, W, McCabe, R, McIntosh, A, Pearsall, R, Sudlow, C, Ward, J, Zammit, S, Hotopf, M