In other studies, it is reported that patients with LRRK2 monogenic PD also perform better than iPD in terms of cognitive ability, smell, sleep, and emotion (Marras et al., 2011, 2016a; Ben Sassi et al., 2012; Saunders-Pullman et al., 2014, 2015). This evidence concerns the gene LRRK2 and Parkinson disease.