Coimmunoprecipitation and Western blot detection were used to determine: 1) the effects of select fragments from the apoE low-density lipoprotein (LDL) binding domain and recombinant apoE subtypes on amyloid beta (Aβ)42-α7 nicotinic acetylcholine receptor (α7nAChR) interaction and tau phosphorylation in rodent brain synaptosomes; and 2) the level of Aβ42-α7nAChR complexes in matched controls and patients with mild cognitive impairment (MCI) and dementia due to AD with known APOE genotypes. This evidence concerns the gene CHRNA7 and Alzheimer disease.