CYP11A1 and early-onset autosomal dominant Alzheimer disease: We question whether this small amount of CYP11A1 can account for the levels of pregnenolone found in human brains range, which range from 5.7 ng/g to 127.44 ng/g tissue with variations seen between different brain regions and between nondemented and Alzheimer’s disease patients (3, 4, 5, 63).