NMNAT2 and Cognitive impairment: The lower levels of NMNAT2, Humanin, PGC1alpha and NRF2, and the resultant impairment in mitochondrial energy production, and the decreased restraint of neuronal apoptosis, protection from neuroinflammation, and regulation of ROS have plausible physiological pathway connections to the GDD complaints of neuropathic pain (Sui et al., 2013) and cognitive impairment (“brain fog”) (Han et al., 2020).