INS and Alzheimer disease: In any way, the desensitization of insulin in the CNS is linked to reduced cerebral glucose uptake, the diminished liberation of lactate, another pivotal energy source for neurons, by astrocytes and chronic glucose hypometabolism (Muddapu et al., 2020), as evident in the brains of both AD (Lyingtunell et al., 1981; Hoyer et al., 1988; Ogawa et al., 1996; Drzezga et al., 2003; Mosconi et al., 2008) and PD patients (Huang et al., 2008; Hosokai et al., 2009; Liepelt et al., 2009; Borghammer et al., 2010; Berti et al., 2012).