Levels of insoluble (guanidine-extractable) (A) and soluble (B) Aβ40 and Aβ42 in the cortex of normal healthy individuals. Occipital cortex was not obtained from the youngest group of controls. Soluble Aβ42 was undetectable in frontal cortex of the youngest control group. Results are given as mean values ± SE and expressed as pg/mg tissue.
* Significant different from the 83–94 ys group, P≤ 0.05
¶ Significant different from the 58–74 ys group, P≤ 0.05