Figure 2. Aβ proteostasis determined by the balance of production and degradation.

The balance of anabolism and catabolism determines the steady‐state quantity of a given protein in a biological system. In FAD, increased anabolism of pathogenic Aβ (Aβ₄₂ and Aβ₄₃) in cortex results in pathological deposition. In SAD, the causes of Aβ accumulation are not fully understood, but an aging‐associated decrease in catabolism is a candidate mechanism (Saido & Iwata, 2006; Hellström‐Lindahl et al, 2008).