Long Term Response to Levodopa in Parkinson's Disease

Levodopa is the most efficacious medication in controlling the motor symptoms of Parkinson's disease (PD). There continues to be a controversy as to whether levodopa remains effective after years of therapy.

To assess the long-term effectiveness of levodopa in PD patients.

The response to levodopa in PD patients undergoing a levodopa challenge for deep brain stimulation (DBS) surgery evaluation from June 1997 through March 2017 were evaluated. The patients were broken into four groups based on disease duration (Group I: 0- 5 years, Group II: 6- 10 years, Group III: 11- 15 years, and Group IV:≥16 years). Levodopa response was calculated based on the changes in Unified Parkinson's Disease Rating Scale (UPDRS) motor and activities of daily living (ADL) scores in the medication ON and OFF states.

A total of 361 PD patients were included. The mean age in Group I was 59.4 years with a mean disease duration of 3.9 years (n = 29), Group II was 61 years with a mean disease duration of 8.1 years (n = 131), Group III was 64 years with a mean disease duration of 12.8 years (n = 143), and IV was 66.5 years with a mean disease duration of 18.5 years (n = 58). There was a significant improvement in UPDRS motor and ADL scores after the levodopa challenge for all groups.

In a subgroup of PD patients who were evaluated for DBS surgery, there was a marked improvement in UPDRS motor and ADL scores which did not decrease with disease progression.