For example, a decrease in CB1R density has been documented in epileptic human hippocampal tissue (Ludányi et al., 2008), in rat hippocampus as a result of chronic stress (Hill et al., 2005; Hillard, 2014), chronic oxidative stress (Li et al., 2020), and in the ventral midbrain of patients with Parkinson's disease (Van Laere et al., 2012). This evidence concerns the gene CNR1 and Parkinson disease.