SLC18A3 and Alzheimer disease: Further studies demonstrated that abnormalities in the cholinergic system develop as the individuals age and accumulate AD pathology since fetuses display a neuronal density and vesicular acetylcholine transporter (VAChT) immunoreactivity comparable to controls and that newborns with DS have ChAT activity levels similar to age-matched controls (Kish et al., 1989; Lubec et al., 2001).