DAs are commonly divided into two groups: ergot and non-ergot-derived agonists. It is noteworthy to consider that DAs are ineffective in patients without therapeutic responses to l-dopa, but they might have a role in patients with advanced PD as a treatment for motor complications related to l-dopa [84]. The use of DAs in advanced PD is discussed separately. Neurologists have debated for years whether to select l-dopa or DAs as initial therapy in relatively young PD patients. DAs should be generally avoided in patients over 70 years due to poor tolerability. Furthermore, presence of cognitive dysfunction at baseline may also influence susceptibility to side effects [82].