PLICAR is a randomized , double-blind , placebo-controlled parallel-groups study where 150 ( N = 50/group ) AAMI participants aged > 55 years will be randomized to receive a daily supplement of Lacprodan PL-20 or one of two placebos ( phospholipid-free milk protein concentrate or inert rice starch ) over a 6-month ( 180-day ) period .