In autoradiographic studies, reductions of the α4 subunit of the nAChR were detected in the range of 50–65% in moderate-severe stage AD (Sihver et al. 1999; Martin-Ruiz et al. 2000) and 30–50% in moderate stage DLB (Martin-Ruiz et al. 2000). This evidence concerns the gene CHRNA4 and Alzheimer disease.