You don't have to run on a treadmill. Find something you enjoy and just do it.
"David A. Snowdon" (born 1952), is an epidemiologist and professor of neurology at the Sanders-Brown Center on Aging at the University of Kentucky. His research interests include antioxidants and aging, and the neuropathology of Alzheimer's disease, especially predictive factors in early life and the role of brain infarction.
He is the director of the Nun Study, a longitudinal study of aging and Alzheimer's disease which is following 678 members of the School Sisters of Notre Dame aged over 75 years. This a longitudinal study of aging and Alzheimer's disease was initiated in 1986 by Snowdon, then at the University of Minnesota. The homogeneous life style of the nuns makes them an ideal study population. Convent archives have been made available to investigators as a resource on the history of participants. The study including reviews of autobiograpical essays by the nuns upon joining the order, administration of memory and cognitive tests to the nuns (some over 100 years of age), and post-mortem examination of their brains.More David Snowdon on Wikipedia.
The ones having strokes were going down a much steeper slope and hitting bottom much earlier.
We can't do anything today to slow down the development of Alzheimer's lesions, ... we can do something about strokes.