Indeed many studies have shown that the pharmacological or the genetic inhibition of Cdk5 activity can prevent synaptic loss and neuronal death and exert some protective effect in mouse models of AD and PD (Lau and Ahlijanian, 2003; Piedrahita et al., 2010; Liu et al., 2016; Seo et al., 2017; He et al., 2018). Here, CDK5 is linked to Parkinson disease.