BDNF Val66Met but not transcranial direct current stimulation affects motor learning after stroke

Area of Science:

• Neuroscience
• Neuromodulation
• Rehabilitation Medicine

Background:

• Transcranial direct current stimulation (tDCS) is a non-invasive neuromodulation technique explored for enhancing motor skill learning post-stroke.
• Previous research on tDCS efficacy in stroke recovery is limited, with unclear roles for activity-dependent BDNF release and stimulation timing.

Purpose of the Study:

• To investigate the influence of activity-dependent BDNF release and the timing of tDCS relative to training on motor skill learning in chronic stroke patients.
• To determine if the BDNF Val66Met genotype modulates the effects of tDCS on motor recovery.

Main Methods:

• A double-blind, between-subjects randomized controlled trial involving 80 chronic stroke patients genotyped for BDNF Val66Met.
• Participants received either short-lasting online tDCS, long-lasting offline tDCS, short-lasting offline tDCS, or sham tDCS.
• Motor skill learning was assessed using the circuit tracing task, measuring improvement from day one to day nine.

Main Results:

• The presence of at least one BDNF Met allele significantly diminished motor skill improvement, highlighting the importance of activity-dependent BDNF release.
• None of the tested tDCS protocols (online or offline) demonstrated a significant effect on motor skill learning improvement.

Conclusions:

• The BDNF Val66Met genotype is a significant determinant of motor skill learning capacity after stroke and may be valuable for prognostic models.
• tDCS did not modulate motor skill learning in this cohort, suggesting its effectiveness may be overestimated or context-dependent.