Levodopa influence on turning dynamics in people with Parkinson's disease.

Turning behaviors are affected in people with Parkinson's disease (PwPD) leading to falls and Freezing of Gait (FOG). Levodopa therapy is commonly recommended for PwPD to help alleviate motor symptoms. Knowledge of turning dynamics with levodopa therapy is limited and could improve clinical care. We enrolled 44 PwPD already on levodopa therapy and analyzed their turns on an instrumented gait mat. Participants made 180-degree turns in their OFF-state (> 8 h off levodopa) then ON-state (1 h after levodopa). Thirteen turn measures were assessed for changes between the OFF- to ON-state. Compared to the OFF-state, in the ON-state turns had significantly faster stride-velocity and fewer steps were taken to complete turns. Regression modeling suggested greater improvement in turn stride-velocity with longer levodopa duration while greater FOG severity was associated with taking fewer steps to turn in ON- compared to the OFF-state. Our data suggests worse OFF-state function and retained levodopa responsiveness leading to larger improvement in turn measures, in those on levodopa longer (or longer disease duration), and in those within our cohort experiencing levodopa unresponsive FOG. Our results provide important evidence for continued aggressive levodopa management to improve mobility during turns even in advanced Parkinson's disease.