Other proteins with lower expression levels in the environment of NFT-bearing neurons of the resilient as compared to cases with dementia included PTEN induced kinase 1 (PINK1), a mitochondrial protein that is upregulated during cellular stress and unusually high energy demands [52], and NADP + -dependent isocitrate dehydrogenase 1 (IDH1), an enzyme critical to glucose metabolism and the primary producer of brain NADPH [3]. Here, PINK1 is linked to dementia.