In the current study, we examined 15 autopsied human brains that included 5 cases of Parkinson disease (PD), 6 cases of Alzheimer disease (AD), and 4 cases of age-matched cognitively normal controls (NC) using immunohistochemistry (IHC) staining for GFAP and Iba1, Aβ and phosphorylated tau, and α-SMA, as well as myelin and axon staining. This evidence concerns the gene ACTA1 and Alzheimer disease.