Clinical Efficacy of Istradefylline for Depression in Parkinson’s Disease

Background: Parkinson’s disease (PD) is a common movement disorder with a wide range of non-motor symptoms. Depression is one of these symptoms; however, its pathomechanism and management remains to be elucidated. We evaluated of istradefylline (ISD), a first selective adenosine A2A receptor antagonist, for the treatment of depression in PD. Method: This was an open-labeled, prospective study that enrolled 15 PD patients (Men 8, Women 7) with motor fluctuations who fully filled UK PD society brain bank clinical diagnostic criteria. We added ISD 20 mg/day for 4 weeks followed with 40 mg/day for next 4 weeks on the preceding anti-parkinsonian medications. We evaluated Patient Health Questionnaire (PHQ-9) and Unified PD Rating Scale (UPDRS) part III (on state) at baseline and 8 weeks follow-up. Results: 14 patients completed the evaluations. PHQ-9 scores improved in 5 patients (responder). PHQ-9 scores of responders at baseline were higher than those of nonresponders; however, there was no significant difference. Furthermore, there were no significant differences in UPDRS part III, age, onset, duration, daily levodopa dose, and levodopa equivalent dose at baseline among both groups. UPDRS part III scores improved in both groups; however, there was also no significant difference between them. Conclusion: ISD could have efficacy to depression in some PD patients.