Does tDCS Improve Motor Learning in Children With DCD?

Transcranial Direct Current Stimulation (tDCS): A Therapeutic Intervention for Motor Impairments in Children With Developmental Coordination Disorder (DCD).

Transcrainial direct current stimulation (tDCS) has become increasingly popular over the past decade. tDCS is a safe and well-studied form of non-invasive brain stimulation. The purpose of the current study is to see if tDCS can improve motor function in children with developmental coordination disorder. Non-invasive brain stimulation is shown to positively affect motor performance in children with neurodevelopmental and/or neurological conditions. For example, tDCS improves hand motor function in children with paediatric stroke and cerebral palsy. The benefits of tDCS in developmental coordination disorder is unknown. The current study will assess children's motor performance before and after tDCS intervention.

Developmental Coordination Disorder (DCD) is a chronic neurodevelopmental disorder characterized by impairments in coordinated motor abilities. Affected individuals show differences in brain maturation and early motor development, negatively impacting performance on everyday living tasks such as writing and participation in sports. Currently, there are few evidence-based therapeutic interventions for individuals diagnosed with DCD, and most are time consuming with modest effect sizes [1]. There is a pressing need to develop efficient, effective interventions to improve motor performance in children with DCD, as impairments often last into adulthood and can negatively impact long-term physical and mental health as well as social and academic abilities. The ability to enhance endogenous motor learning systems with non-invasive brain stimulation is now well established in adults [2, 3]. Research studies have demonstrated the same potential in the developing brain. For instance, tDCS can significantly enhance the acquisition of motor skills over a few brief training sessions in typically developing school aged children, with lasting effects [4]. Recent clinical trials in children with cerebral palsy and neonatal stroke also suggest therapeutic efficacy in children with motor impairment [5, 6, 7]. However, the use of tDCS in pediatric populations is limited [8]. As tDCS has been associated with improved motor outcomes in adults and children with motor impairment, it may be an effective intervention for children with DCD. This however has not been investigated. Research Questions & Objectives: The current study will investigate the therapeutic benefits of tDCS in adolescents with DCD. The primary aim is to determine changes in motor skill acquisition and learning during a skill-training paradigm that is paired with anodal tDCS or sham tDCS. We hypothesize that when compared to the sham tDCS group, the treatment tDCS group will show enhanced motor learning on tests of motor functioning. Secondarily we will also examine sensorimotor changes following tDCS intervention and pediatric brain stimulation safety/tolerability. Methods: A randomized, sham controlled clinical trial including a final sample of 30 school aged children diagnosed with DCD will be conducted. The current study will be using a well-supported stimulation protocol, utilized in children and adolescents in the absence of adverse side effects.

The currently proposed study is a randomized, sham controlled clinical trial that includes 30 adolescents diagnosed with DCD. Participants will be randomized to one of two tDCS treatment groups.

Participants will not be informed of the stimulation group to which they are randomized. Both stimulation groups produce similar transient scalp sensations in participants and the sham protocol that will be used has been shown to be valid and ensures that participants are naïve to their assigned treatment group [9]. Participants will be asked which stimulation group they felt they took part in to ensure adequate blinding. Outcomes assessors will be blinded. Offline video analysis will be used to score motor assessment performance. These videos will exclude all identifying information including the participant's face and their stimulation group.

Transcrainial Direct Current Stimulation (tDCS): The right primary motor cortex will be localized and a saline soaked sponge electrode will be placed onto M1 with a second saline soaked sponge electrode placed on the contralateral supraorbital region.

Transcrainial Direct Current Stimulation (tDCS): The right primary motor cortex will be localized and a saline soaked sponge electrode will be placed onto M1 with a second saline soaked sponge electrode placed on the contralateral supraorbital region.

Transcranial direct current stimulation (tDCS) is a safe non-invasive form of brain stimulation, which modulates, through the application of weak direct current, cortical excitability. The applied subthreshold current passes through two externally placed electrodes, an anode and cathode.

The PPT is a valid measure of fine motor coordination, hand dexterity, and motor learning skills, which consists of 4 subtests: left hand peg placement [PPTL], right hand peg placement [PPTR], bimanual peg placement [PPTLR], and bimanual assembly [PPTA]. The PPT peg placement subtests involve placing as many pins as possible into a pegboard during a 30 second interval. The total number of pegs, or pairs of pegs, placed are counted and scored. The PPT assembly subtest involved building as many copies of a demonstration structure using pins, pegs, and washers within a 60 second time period.

The JTT is an upper extremity motor assessment aimed at testing practical everyday living skills, such as writing, picking up coins, and moving objects. Left and right hands are tested independently, and scores for each hand are obtained through recording task completion time.

The SRTT is a measure of motor learning skills. Participants are cued on a computer monitor to press the indicated letter on the keyboard. Participants complete this task over eight blocks of trials, each consisting of 96 cued key commands.

Sensorimotor changes will be measured between baseline, post-training, and 6 week follow-up using the Kinesiological Instrument for Normal and Altered Reaching Movements (KINARM, BKIN Technologies Ltd, Ontario, Canada). The KINARM robot is a valid and reliable tool that can be used to measure children's proprioceptive, sensorimotor, visuomotor and motor decision/control abilities.

Inclusion Criteria: Diagnosed and documented DCD (including individuals with additional diagnoses of attention and/or learning disorders) Aged 10 to 15 years Right Handed Exclusion Criteria: Presence of implanted electrical devices, metallic implants, and/or irremovable metal objects (i.e., cardiac pacemakers, braces etc.) Pregnancy or possibility of pregnancy Diagnosed with a neuropsychiatric disorder such as autism spectrum disorder or chronic medical condition such as cerebral palsy or epilepsy Taking prescribed medications

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Grohs MN, Craig BT, Kirton A, Dewey D. Effects of Transcranial Direct Current Stimulation on Motor Function in Children 8-12 Years With Developmental Coordination Disorder: A Randomized Controlled Trial. Front Hum Neurosci. 2020 Dec 11;14:608131. doi: 10.3389/fnhum.2020.608131. eCollection 2020.