Analysis of brain scans and cognitive scores of 64 older adults from the NIA's Baltimore Longitudinal Study of Aging (average age 76) has found that, between the most cognitively stable and the most declining (over a 12-year period), there was no significant difference in the total amount of amyloid in the brain, but there was a significant difference in the location of amyloid accumulation. The stable group showed relatively early accumulation in the frontal lobes, while the declining group showed it in the temporal lobes.
(2013). Memory decline shows stronger associations with estimated spatial patterns of amyloid deposition progression than total amyloid burden.
Neurobiology of Aging. 34(12), 2835 - 2842.