CHAT and Alzheimer disease: Next, we expanded the pilot experiment and investigated in more detail the modulation of ChAT activity by Aβ peptides at a broad concentration range of Aβ40 and Aβ42, encompassing the possible physiological concentrations representative of CSF Aβ concentrations of patients with AD (notably ∼4 and 0.4 ng/mL for Aβ40 and Aβ42, respectively) and of healthy controls (∼6.4 and 0.8 ng/mL for Aβ40 and Aβ42, respectively).