CHICAGO, March 8 (Reuters) - Alzheimer's disease will cost the United States an estimated $200 billion in healthcare costs in 2012, and more than half of that -- $140 billion -- will be paid by Medicare and Medicaid, the Alzheimer's Association said on Thursday. In its 2012 Facts and Figures report, the advocacy group estimates that total healthcare payments for Americans with Alzheimer's and other dementias will rise to $1.1 trillion in 2050.