In the present study, we combined comorbid Alzheimer’s and atherosclerosis using the viral injection of a gain-of-function mutation of PCSK9 (with a Western diet) in the APP/PS1 mouse strain50,51 to assess how AD alone, atherosclerosis alone, and mixed AD and atherosclerosis impact recognition memory, amyloid pathology, and sensory-induced vascular function in the awake mouse.52 The gene discussed is PCSK9; the disease is Alzheimer disease.