GCLC and Alzheimer disease: We and others have observed an age- and AD-related decline in GSH (Ghosh et al., 2012, 2014; Zhang et al., 2012); however, several attempts to increase GSH levels by overexpressing γ-glutamyl cysteine synthetase (Gclc) or GR have failed to increase longevity (Perez et al., 2009) or improve memory.