Therefore, in our current study, we performed an extensive examination of PACAP-38 levels with the ELISA method in plasma samples of PD patients to detect the changes in PACAP-38 levels compared to age-matched healthy control individuals and, consequently, to find possible relationships and correlations with different PD scales focusing on motor symptoms and different therapeutic methods such as DBS. Here, ADCYAP1 is linked to Parkinson disease.