In addition, the age-dependent decrease of LTCCs (Branch et al., 2014; Ortner et al., 2017) could limit the therapeutic window of DHPs in PD (especially in elderly patients), although disease state seems to affect LTCC expression [SN neurons from MPTP-treated mice (Verma and Ravindranath, 2019) and post-mortem brains of early-stage PD patients (Hurley et al., 2015) showed robust Cav1.3 levels, despite profound neuron loss]. This evidence concerns the gene CACNA1D and Parkinson disease.