Blinding of transcranial direct current stimulation is compromised in
typically-developing children compared to young adults
Abstract
Achieving successful blinding is a persistent challenge for clinical
trials involving transcranial direct current stimulation. Studies
involving populations with increased sensory sensitivity, such as
children, could be at risk for increased bias from inadequate blinding
due to unique sensation of stimulation relative to adults. The
objectives of this study were 1) To examine differences in transcranial
stimulation blinding between children and young adults and its
relationship to sensory sensitivity. 2) To test the efficacy of an
ActiSham protocol for participant blinding, compared to a traditional
sham protocol. Typically developing right-handed children (N=11, 5-14
yr) and young adults (N=14, 15-25 yr) completed a single-session study
to test transcranial stimulation blinding after three conditions
counterbalanced across participants: Active, Sham, and ActiSham.
Stimulation was paired with a motor learning task to simulate a
combinatory neurorehabilitation intervention. After each condition,
participants reported if they received real or fake stimulation and
their response confidence. To quantify sensory sensitivity, participants
completed the Sensory Profile (2nd edition). Compared to a chance level,
1) children and young adults correctly identified Active stimulation, 2)
children incorrectly identified Sham and ActiSham stimulation, 3) young
adults identified Sham and ActiSham stimulation at chance-level.
Blinding accuracy was not related to sensory sensitivity. Children
report stimulation as real stimulation with higher confidence for almost
all conditions, indicating unsuccessful blinding compared to young
adults. Future studies should consider alternative sham protocols or
methods to improve blinding in child participants.