# Patient Selection in Deep Brain Stimulation: A Role for Transcranial Direct Current Stimulation to Enhance the Levodopa Challenge?

## TL;DR

This study suggests that transcranial direct current stimulation (tDCS) can enhance the effects of levodopa in Parkinson's patients and may help identify better candidates for deep brain stimulation.

## Contribution

The study introduces the use of tDCS to improve levodopa response as a potential tool for selecting patients for DBS.

## Key findings

- Levodopa improved motor performance more after tDCS than after sham stimulation.
- The combined levodopa-tDCS response predicted outcomes in patients who later received DBS.
- Targeted tDCS may help optimize DBS candidate selection.

## Abstract

Dopaminergic medication and deep brain stimulation (DBS) improve motor symptoms in Parkinson's disease (PD), but levodopa response alone may not predict DBS outcomes. We retrospectively analyzed 19 PD patients undergoing levodopa challenges with and without prior transcranial direct current stimulation targeting a defined PD response network. Levodopa improved motor performance more after tDCS than sham (41.72% vs. 31.52%; p < 0.001). In ten patients who later received DBS, the combined levodopa‐tDCS response accounted for DBS outcomes (p = 0.02). These findings suggest that targeted tDCS enhances levodopa effects and may be of potential use to optimize DBS candidate selection.