Review: Transcranial direct current stimulation in ADHD shows clinical effects

If children are constantly fidgeting, impulsive and unfocused, this may in some cases be due to attention deficit hyperactivity disorder (ADHD). This disorder is particularly problematic in everyday school life and impairs the development of the affected children and adolescents. Transcranial direct current stimulation (tDCS) could be helpful here. In a review, IfADo PhD student Ali Salehinejad and neuroscientists from Iran, Netherlands and Italy critically analyzed already published studies. The review is currently published in the journal „Neuroscience Bulletin“.

If children or adults suffer from ADHD, this can manifest itself in a variety of symptoms. Frequently, a pronounced impulsiveness and inattention occurs, accompanied by physical restlessness and lack of concentration. Transcranial direct current stimulation (tDCS) could be a promising method for this disorder. The brain is stimulated with very low current intensity via electrodes on the scalp, so that certain areas of the brain are stimulated or inhibited. The procedure is non-invasive and painless. IfADo is exploring the potential of this technology. In a recent publication, neuroscientists around Ali Salehinejad have now evaluated the effectiveness of the method in ADHD on the basis of 14 studies with a total of 278 test persons.

The effectiveness of tDCS in ADHD

Ten of the 14 studies showed at least a gradual improvement in cognitive deficits (reaction inhibition, working memory, attention, cognitive flexibility) or clinical symptoms (e.g. impulsiveness, inattention). The most prominent positive effects were seen when the left frontal part of the cerebral cortex was treated. In adults with ADHD, a current intensity of 2 milliamperes was associated with a significant improvement, whereas 1 milliampere was sufficient in children. Four studies showed no significant or only very small effects. No serious adverse effects during or after tDCS were reported in the studies.

Application depends on individual symptoms

Schematic representation of transcranial direct current stimulation (tDCS)
Schematic representation of transcranial direct current stimulation (tDCS)

Ali Salehinejad summarizes that the type of tDCS application should be tailored to the individual patient. On the one hand, the different symptoms are related to different brain regions. On the other hand, it might be advantageous to adapt to stimulation parameters such as intensity and duration to the individual patient. Particularly in children, it should also be taken into account that they are still developing.

Overall, tDCS appears to be a promising method for improving ADHD deficits. However, the clinical use of tDCS in ADHD requires further systematic investigations with larger samples.


Publication:

Salehinejad MA, Nejati V, Mosayebi-Samani M, Mohammadi A, Wischnewski M, Kuo M-F, Avenanti A, Vicario CM, Nitsche MA (2020) Transcranial Direct Current Stimulation in ADHD: A Systematic Review of Efficacy, Safety, and Protocol-induced Electrical Field Modeling Results. Neurosci Bull. https://doi.org/10.1007/s12264-020-00501-x

Contact:
M.Sc. Mohammed Ali Salehinejad
Research Topic Neuromodulation
Phone: +49 / 231 1084 476
Email: salehinejad@ifado.de

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