“A treatment breakthrough that delayed the age of onset of Alzheimer’s disease by five years and began to show its effects in 2015 would decrease the total number of Americans age 65 and older with Alzheimer’s disease from 5.6 million to 4 million by 2020.  As a result, 1.6 million Americans who would be expected to have the condition in 2020 would be free of the condition.  In addition, five years later, in 2025, 2.7 million Americans–42 percent of the 6.5 million people who would be expected to have Alzheimer’s in that year–would be disease free.  The biggest effect would be in 2050 when 5.8 million people–43 percent of the 13.5 million Americans who would be expected to have Alzheimer’s without the breakthrough–would not have the condition.”