However, levels of PACAP have been also associated with other cognitive diseases such as schizophrenia (Ago et al. 2018; Hashimoto et al. 2007; Vacic et al. 2011), with recent evidence correlating increased PACAP expression with schizophrenia related to suicide (Slabe et al. 2023), which indicates that therapeutic initiatives in PD should carefully monitor potential side effects. This evidence concerns the gene ADCYAP1 and Parkinson disease.