Rate of progression of cognitive decline in Alzheimer's disease: effect of butyrylcholinesterase K gene variation. by Holmes, C, Ballard, C, Lehmann, D, David Smith, A, Beaumont, H, Day, I, Nadeem Khan, M, Lovestone, S, McCulley, M, Morris, C, Munoz, D, O'Brien, K, Russ, C, Del Ser, T, Warden, D