CHRNA7 and Parkinson disease: The hippocampus, abundant in α7 nAChRs, was quantitatively evaluated for [125I]α-bungarotoxin ([125I]α-Bgtx) binding to α7 nAChRs in postmortem human PD (n = 26; 12 male, 14 female) and cognitively normal (CN) (n = 29; 14 male, 15 female) brain slices.