Non-invasive Transcranial Electrical Stimulation (TES) shows early promise to treat ADHD symptoms in children

While tDCS uses con­stant cur­rent inten­si­ty, tRNS and tACS use oscil­lat­ing cur­rent. The ver­ti­cal axis rep­re­sents the cur­rent inten­si­ty in mil­liamp (mA), while the hor­i­zon­tal axis illus­trates the time-course. Source: Wikipedia.

Many chil­dren with ADHD ben­e­fit from med­ica­tion treat­ment, behav­ioral treat­ment, or their com­bi­na­tion, but oth­ers do not. In addi­tion, par­ents are often reluc­tant to start their child on med­ica­tion and high qual­i­ty behav­ioral treat­ments are not read­i­ly acces­si­ble in many areas. The long-term effi­ca­cy of these treat­ments is also less than desir­able. Thus, despite these evi­dence-based ADHD treat­ments, there is a press­ing need to devel­op nov­el treat­ments with strong research support.

A study pub­lished recent­ly in Trans­la­tion­al Psy­chi­a­try [Dakawar-Kawar et al (2023). Tran­scra­nial ran­dom noise stim­u­la­tion com­bined with cog­ni­tive train­ing for treat­ing ADHD: a ran­dom­ized sham-con­trolled tri­al.] reports promis­ing results for a nov­el ADHD treat­ment approach.

The Study:

Study par­tic­i­pants were 24 6–12 year-old chil­dren recent­ly diag­nosed with ADHD fol­low­ing a com­pre­hen­sive eval­u­a­tion. They were ran­dom­ly assigned to receive either a) a type of Tran­scra­nial Elec­tri­cal Stim­u­la­tion (TES) called Tran­scra­nial Ran­dom Noise Stim­u­la­tion (TRNS) or b) sham stim­u­la­tion; chil­dren in both groups engaged in com­put­er­ized cog­ni­tive train­ing dur­ing the sessions. 

In Tran­scra­nial Elec­tri­cal Stim­u­la­tion (TES), a weak elec­tric cur­rent is deliv­ered to the brain via scalp elec­trodes, cre­at­ing an elec­tric field that mod­u­lates neu­ronal activ­i­ty. The safe­ty pro­file of this pro­ce­dure is excel­lent and side effects are min­i­mal. The the­o­ry behind TES as an ADHD treat­ment is that it may help nor­mal­ize neu­ronal activ­i­ty in youth with ADHD, and thus dimin­ish their symp­toms., par­tic­u­lar­ly atten­tion problems.

Cog­ni­tive train­ing was com­bined with TRNS based on the hypoth­e­sis that hav­ing youth engaged in active cog­ni­tive train­ing dur­ing stim­u­la­tion may enhance the ben­e­fits of stim­u­la­tion. The com­put­er­ized cog­ni­tive train­ing pro­gram used in this study was called ACTIVATE.

Par­tic­i­pants com­plet­ed 20 min­utes ses­sions per day for 10 days across a 2‑week peri­od. Researchers who con­duct­ed the ses­sions were blind to whether par­tic­i­pants received actu­al TRNS or sham stim­u­la­tion. Par­tic­i­pants and their par­ents were also kept blind to con­di­tion. When par­ents were asked after the study whether their child had received active or sham treat­ment, they did no bet­ter than chance at iden­ti­fy­ing their child’s condition.

The Results:

The pri­ma­ry out­come for the study was the ADHD rat­ing scale, a stan­dard­ized and wide­ly-used behav­ior rat­ing scale of ADHD symp­toms. Par­ents com­plet­ed this before treat­ment began, imme­di­ate­ly fol­low­ing the 2‑week treat­ment, and again 3 weeks lat­er so that the dura­tion of any ben­e­fits could be assessed.

Fol­low­ing treat­ment, ADHD symp­tom rat­ings pro­vid­ed by par­ents were sig­nif­i­cant­ly low­er for the TRNS group (includ­ing cog­ni­tive train­ing) com­pared to the sham treat­ment group (includ­ing cog­ni­tive train­ing), con­trol­ling for base­line scores. These dif­fer­ences remained evi­dent 3 weeks after treat­ment ended.

Using a 30% reduc­tion in symp­toms from base­line as an indi­ca­tor of pos­i­tive treat­ment response, 55% of the TRNS group were respon­ders com­pared to only 17% in the sham group. At the 3‑week fol­lowup, the per­cent of respon­ders were 64% and 33% respectively.

Summary and implications:

This is the first study to exam­ine a spe­cif­ic type of tran­scra­nial elec­tri­cal stim­u­la­tion called TRNS as a treat­ment for chil­dren with ADHD. As dis­cussed above, promis­ing result were obtained in that chil­dren receiv­ing active treat­ment showed sig­nif­i­cant reduc­tions in par­ent-rat­ed ADHD symp­toms com­pared to those who received sham treat­ment. This is an encour­ag­ing find­ing. Fur­ther­more, these dif­fer­ences per­sist­ed across the 3‑week followup.

A strength of this study is that it was a true ran­dom­ized-con­trolled tri­al in which research staff pro­vid­ing the treat­ment, par­tic­i­pants, and par­ents were all blind to con­di­tion. Fur­ther­more, the authors con­firmed that par­ents were no bet­ter than chance in guess­ing which con­di­tion their child was in. The study would thus be con­sid­ered to have uti­lized a gold-stan­dard design ito eval­u­ate this nov­el treatment.

As the authors them­selves note, how­ev­er, these results should be con­sid­ered pre­lim­i­nary and require repli­ca­tion with a sub­stan­tial­ly larg­er sam­ple than the 24 youth who par­tic­i­pat­ed here. This is required before any con­clu­sions about the effi­ca­cy of this approach can be made.

Sub­se­quent research on this approach would also be strength­ened by includ­ing teacher reports to hope­ful­ly con­firm that improve­ments are also observed in school. Teach­ers could pro­vide espe­cial­ly valu­able infor­ma­tion on whether aca­d­e­m­ic per­for­mance, a fre­quent prob­lem in youth with ADHD, is pos­i­tive­ly impact­ed by treatment.

It would also be use­ful to know whether the cog­ni­tive train­ing which accom­pa­nied TRNS ses­sions in this study are nec­es­sary for any ben­e­fits to occur. This could be done by includ­ing addi­tion­al groups in which stim­u­la­tion is pro­vid­ed with­out the cog­ni­tive train­ing employed here.

While cer­tain­ly not con­clu­sive, results from this inter­est­ing study are suf­fi­cient­ly promis­ing to war­rant a larg­er ran­dom­ized con­trolled tri­al. Hpe­ful­ly, results from such a study will become avail­able soon.

– Dr. David Rabin­er is a child clin­i­cal psy­chol­o­gist and Direc­tor of Under­grad­u­ate Stud­ies in the Depart­ment of Psy­chol­o­gy and Neu­ro­science at Duke Uni­ver­si­ty. He pub­lish­es the Atten­tion Research Update, an online newslet­ter that helps par­ents, pro­fes­sion­als, and edu­ca­tors keep up with the lat­est research on ADHD.

The Study in Context:

• Does ADHD treat­ment enable long-term aca­d­e­m­ic suc­cess? (Yes, espe­cial­ly when phar­ma­co­log­i­cal and non-phar­ma treat­ments are combined)
• Evi­dence review: Phys­i­cal exer­cise helps boost atten­tion, cog­ni­tive flex­i­bil­i­ty and inhibito­ry con­trol in chil­dren and ado­les­cents with ADHD