For instance, proteins that are related to high cellular stress and energy demands that are upregulated in response to oxidative stress, such as, PTEN induced kinase 1 (PINK1) and NADP + dependent isocitrate dehydrogenase 1 (IDH1), were reduced in the microenvironment of NFT-bearing neurons in the hippocampus of post-mortem tissue from resilient donors compared with AD patients [98], indicating that resilient donors might have reduced levels of oxidative stress. Here, PINK1 is linked to Alzheimer disease.