FIS1 and Alzheimer disease: For instance, compared to a control group of age-matched neurons, neurons from AD show a marked reduction in the proportion of normal mitochondria and a notable rise in the proportion of mitochondria with broken cristae.184 In addition, Opa1, Drp1, MFN1/2 expression are significantly lower in AD, whereas Fis1 levels are higher in AD.185 Mitochondrial dynamics impact the pathological changes of AD involved in several signaling pathways, including Ca2+, AMPK, and nitric oxide signaling pathways.