Fig. 9

Conceptual model of early changes in AD. Before a clinical diagnosis of Alzheimer’s disease (AD), decades of Aβ peptide deposition lead to plaque formation in pre-symptomatic and prodromal stages of the disease. Incorporating Aβ34 (marker of enzymatic Aβ degradation) with measures of Aβ42 (marker for cerebral Aβ deposition) could complement current biomarker assessments and provide additional information about Aβ turnover