Transcranial magnetic stimulation / transcranial direct current stimulation (o/+)

Various studies have looked at the effect of transcranial stimulation on ADHD.¹²³
Transcranial direct current stimulation was rated better than repetitive transcranial magnetic stimulation in a review.⁴

According to the majority opinion, there are predominantly indications of a positive effect.^56789101112

A meta-analysis found a significant positive effect in 8 (n = 133) of 13 studies (n = 308) rather in children and adolescents for inattention, impulsivity and general symptom levels, with a delayed onset of effect for hyperactivity.¹³ Another meta-analysis found significant improvements in attention, inhibition, working memory and brain connectivity in 11 studies.¹⁴
Studies found improvements through transcranial stimulation in relation to:

• fewer omission errors in people with ADHD, along with an improvement in P 300 amplitude¹⁵
• Improvements in ADHD, which were further enhanced by a combination with cognitive training¹⁶
• Hyperactivity
  • Hyperactivity improved, but not attention (individual case of an adult with ADHD)¹⁷¹⁸
  • Hyperactivity/impulsivity improved at home¹⁹
  • 1 Hz rTMS over the left dlPFC improved hyperactivity/impulsivity (and inattention) in children with ADHD²⁰, unlike 10 Hz stimulation of the right dlPFC, which did not improve ADHD symptoms compared to sham stimulation²¹
• Attention
  • 1 Hz rTMS over the left dlPFC improved inattention (and hyperactivity/impulsivity) in children with ADHD²⁰, unlike 10 Hz stimulation of the right dlPFC, which did not improve ADHD symptoms compared to sham stimulation²¹
  • Attention improved without improvement in mood, anxiety or hyperactivity in adults with ADHD²²
  • Attention improved, but not overall ADHD scores in children and adolescents with ADHD²³
  • Improved attention in the school context¹⁹
  • Improved maintenance of the drive²⁴
• oppositional defiant behavior¹⁹
• Risk assessment and reward discounting²⁵
• Working memory
  • through optimized high-resolution tACS with a frequency of 5 Hz above the left DLPFC²⁶

Other sources report mixed results.^27282930 One study found no improvement with transcranial direct current treatment over the left dorsolateral PFC.³¹

Several studies found evidence of increased (extracellular) dopamine levels in the striatum during or after TMS application.³²³³ The increase corresponded to that seen with the administration of D-amphetamine.³⁴

One study reports a better effect of repetitive TMS application on ADHD than with the antipsychotic tiapride. A combination further improved the effect.³⁵
Nevertheless, we consider antipsychotics to be unsuitable for the treatment of ADHD.

One study reported that the smaller the following brain regions were, the better the effect of tDCS on inattention:³⁶

• left dlPFC
• middle frontal gyrus
• inferior frontal gyrus
• left ACC supragenual

Transcranial random noise stimulation (tRNS) over the prefrontal cortex during a time perception task tended to improve the accuracy of time perception in the ADHD group and brought their performance closer to accurate time intervals. In contrast, the accuracy of time perception decreased in the healthy control group.³⁷