ENPEP and Parkinson disease: In pathological conditions, the concentration of APα is significantly reduced in the brains of humans with AD (Marx et al., 2006; Smith et al., 2006; Naylor et al., 2010), with PD (di Michele et al., 2003; Luchetti et al., 2010) as well as from the brains of a transgenic mouse model of AD (Wang et al., 2007, 2010).