October 24, 2025

Meta-analysis of Transcranial Direct Current Stimulation Still Yields Little Sign of Efficacy

Background:

Despite recommendations for combined pharmacological and behavioral treatment in childhood ADHD, caregivers may avoid these options due to concerns about side effects or the stigma that still surrounds stimulant medications. Alternatives like psychosocial interventions and environmental changes are limited by questionable effectiveness for many patients. Increasingly, patients and caregivers are seeking other therapies, such as neuromodulation – particularly transcranial direct current stimulation (tDCS). 

tDCS seeks to enhance neurocognitive function by modulating cognitive control circuits with low-intensity scalp currents. There is also evidence that tDCS can induce neuroplasticity. However, results for ADHD symptom improvement in children and adolescents are inconsistent. 

The Method:

To examine the evidence more rigorously, a Taiwanese research team conducted a systematic search focusing exclusively on randomized controlled trials (RCTs) that tested tDCS in children and adolescents diagnosed with ADHD. They included only studies that used sham-tDCS as a control condition – an essential design feature that prevents participants from knowing whether they received the active treatment, thereby controlling for placebo effects. 

The Results:

Meta-analysis of five studies combining 141 participants found no improvement in ADHD symptoms for tDCS over sham-TDCS. That held true for both the right and left prefrontal cortex. There was no sign of publication bias, nor of variation (heterogeneity) in outcomes among the RCTs.  

Meta-analysis of six studies totaling 171 participants likewise found no improvement in inattention symptoms, hyperactivity symptoms, or impulsivity symptoms for tDCS over sham-TDCS. Again, this held true for both the right and left prefrontal cortex, and there was no sign of either publication bias or heterogeneity. 

Most of the RCTs also performed follow-ups roughly a month after treatment, on the theory that induced neuroplasticity could lead to later improvements. 

Meta-analysis of four RCTs combining 118 participants found no significant improvement in ADHD symptoms for tDCS over sham-TDCS at follow-up. This held true for both the right and left prefrontal cortex, with no sign of either publication bias or heterogeneity. 

Meta-analysis of five studies totaling 148 participants likewise found no improvement in inattention symptoms or hyperactivity symptoms for tDCS over sham-TDCS at follow-up. AS before, this was true for both the right and left prefrontal cortex, with no sign of either publication bias or heterogeneity. 

The only positive results came from meta-analysis of the same five studies, which reported a medium effect size improvement in impulsivity symptoms at follow-up. Closer examination showed no improvement from stimulation of the right prefrontal cortex, but a large effect size improvement from stimulation of the left prefrontal cortex

Interpretation: 

It is important to note that the one positive result was from three RCTs combining only 90 children and adolescents, a small sample size. Moreover, when only one of sixteen combinations yields a positive outcome, that begins to look like p-hacking for a positive result. 

In research, scientists use something called a “p-value” to determine if their findings are real or just due to chance. A p-value below 0.05 (or 5%) is considered “statistically significant,” meaning there's less than a 5% chance the result happened by pure luck. 

When testing twenty outcomes by this standard, one would expect one to test positive by chance even if there is no underlying association. In this case, one in 16 comes awfully close to that. 

To be sure, the research team straightforwardly reported all sixteen outcomes, but offered an arguably over-positive spin in their conclusion: “Our study only showed tDCS-associated impulsivity improvement in children/adolescents with ADHD during follow-ups and anode placement on the left PFC. ... our findings based on a limited number of available trials warrant further verification from large-scale clinical investigations.” 

Chun-Bin Tunga, Shun-Chin Liang, Cheuk-Kwan Sun, Yu-Shian Cheng, and Kuo-Chuan Hung, “Behavioral outcomes after tDCS treatment during immediate post-intervention and follow-up periods in children and adolescents diagnosed with attention-deficit/hyperactivity disorder: a systematic review and meta-analysis on randomized sham-controlled trials,” Journal of Psychiatric Research 191 (2025) 8-14, https://doi.org/10.1016/j.jpsychires.2025.09.008

Related posts

New Non-Stimulant ADHD Drug: Clinical Trial Results

The Newest Non-stimulant Medication for ADHD

Centanafadine, which is currently under investigation as a treatment for ADHD, will be the first triple reuptake inhibitor for the disorder if it is approved by the FDA. It improves norepinephrine, dopamine and serotonin levels. This new medication is not a stimulant, but due to the dopamine component, it has a stimulant-like effect in patients. In adults, two phase 3 trials and a year-long extension have shown sustained benefits and a tolerable safety profile, laying the groundwork for pediatric research.

Based on this study, improvement was already noticeable after the first week and held steady through week 6. The lower dose (164.4 mg) didn’t separate from placebo, reminding us that getting the dose right will be critical. The effect size was smaller than what is seen for stimulants but 50% of patients had excellent outcomes as indicated by reductions in the ADHD-RS of 50% or more.

Side effect patterns look familiar to anyone who prescribes ADHD medications; loss of appetite, nausea and headaches topped the list. About half of teens on the higher dose reported at least one treatment-emergent adverse event, compared with a quarter of those on placebo. Severe reactions were rare but did include isolated liver enzyme spikes, rash, and a few reports of aggression or somnolence. For everyday practice, that translates to routine growth checks, a look at baseline liver function, and clear guidance to families about reporting rashes or mood changes promptly.

The researchers noted that the study had certain limitations, including limited generalizability to adolescents beyond North America, the exclusion of teacher ratings on the ADHD-RS-5 scale and the study’s short duration. They added that future studies should explore long-term treatment outcomes and efficacy compared with other ADHD treatments, as well as its effect on treating ADHD with comorbid conditions.

Why should this matter to clinicians already juggling multiple non-stimulant options for ADHD?

First, speed. Centanafadine separated from placebo within a week. In this regard, it might be closer to stimulants than to the multi-week ramp-up we expect from current non-stimulants. Second, it offers another option when stimulants are contraindicated or poorly tolerated, or when they raise diversion concerns. Its mechanism also makes it intriguing for patients who need both norepinephrine and dopamine coverage but prefer to avoid schedule II drugs. Because it also improves serotonergic transmission, it may be useful for some of ADHD’s comorbidities (see our new article for evidence about serotonin’s role in these disorders).

Keep in mind that centanafadine for ADHD is still investigational, so participation in clinical trials remains the only access route.

August 5, 2025

Transcranial Direct Current Stimulation: Can It Treat ADHD?

How effective and safe is transcranial direct current stimulation for treating ADHD?

ADHD is hypothesized to arise from 1) poor inhibitory control resulting from impaired executive functions which are associated with reduced activation in the dorsolateral prefrontal cortex and increased activation of some subcortical regions; and 2)hyperarousal to environmental stimuli, hampering the ability of the executive functioning system, particularly the medial frontal cortex, orbital and ventromedial prefrontal areas, and subcortical regions such as the caudate nucleus, amygdala, nucleus accumbens, and thalamus, to control the respective stimuli.

These brain anomalies, rendered visible through magnetic resonance imaging, have led researchers to try new means of treatment to directly address the deficits. Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique that uses a weak electrical current to stimulate specific regions of the brain.

Efficacy:

A team of researchers from Europe and ran performed a systematic search of the literature and identified fourteen studies exploring the safety and efficacy of tDCS. Three of these studies examined the effects on ADHD symptoms. They found a large effect size for the inattention subscale and a medium effect size for the hyperactivity/impulsivity. Yet, as the authors cautioned, "a definite conclusion concerning the clinical efficacy of tDCS based on the results of these three studies is not possible."

The remaining studies investigated the effects on specific neuropsychological and cognitive deficits in ADHD:

  •  Working memory was improved by anodal stimulation - but not cathodal stimulation - of the left dorsolateral prefrontal cortex. Anodal stimulation of the right inferior frontal gyrus had no effect.
  •  Response inhibition: Anodal stimulation of the left or right dorsolateral prefrontal cortex was more effective than anodal stimulation of the bilateral prefrontal cortex.
  • Motivational and emotional processing was improved only with stimulation of both the dorsolateral prefrontal cortex and orbitofrontal cortex.

The fact that heterogeneity in the methodology of these studies made meta-analysis impossible means these results, while promising, cannot be seen as in any way definitive.

Safety:

Ten studies examined childhood ADHD. Three found no adverse effects either during or after tDCS. One study reported a feeling of "shock" in a few patients during tDCS. Several more reported skin tingling and itching during tDCS. Several also reported mild headaches.

The four studies of adults with ADHD reported no major adverse events. One study reported a single incident of acute mood change, sadness, diminished motivation, and tension five hours after stimulation. Another reported mild instances of skin tingling and burning sensations.

To address side effects such as tingling and itching, the authors suggested reducing the intensity of the electrical current and increasing the duration. They also suggested placing electrodes at least 6 cm apart to reduce current shunting through the ski. For children, they recommended the use of smaller electrodes for better focus in smaller brains.

The authors concluded, "The findings of this systematic review suggest at least a partial improvement of symptoms and cognitive deficits in ADHD by tDCS. They further suggest that stimulation parameters such as polarity and site are relevant to the efficacy of tDCS in ADHD. Compared to cathodal stimulation, Anodal tDCS seems to have a superior effect on both the clinical symptoms and cognitive deficits. However, the routine clinical application of this method as an efficient therapeutic intervention cannot yet be recommended based on these studies ..."

January 10, 2022

Meta-Analysis Finds No Significant Benefit For ADHD Patients in tCDS

New Meta-analysis Finds No Significant Gains from Transcranial Direct Stimulation (tCDS)

Noting that "despite a lack of solid evidence for their use, rTMS [repetitive transcranial magnetic stimulation]and tDCS [transcranial direct current stimulation] are already offered clinically and commercially in ADHD," and that a recent meta-analysis of ten tDCS studies found small but significant improvements in outcomes, but had several methodological shortcomings and did not include two studies reporting mostly null effects, a team of British neurologists performed a meta-analysis of all twelve sham-controlled, non-open-label, studies found in a comprehensive search of the peer-reviewed literature.

Ten of the twelve randomized-controlled trials used anodal stimulation of the dorsolateral prefrontal cortex, while the other two used anodal stimulation of the right inferior frontal cortex.

The trials explored several measures of cognition. The research team carried out a meta-analysis of all twelve trials, with a total of 232 participants, and found no significant improvement in attention scores from CDC, relative to sham stimulation. A second meta-analysis, of eleven trials with a total of 220 participants, assessed the efficacy of tDCS on improving inhibition scores, and again found no significant effect. A third meta-analysis, encompassing eight trials with a total of 124 participants, evaluated the efficacy of tDCS on improving processing speed scores, once again finding no significant effect.

The latter two meta-analyses approached the border of significance, prompting the authors to speculate that larger sample sizes could bring the results just over the threshold of significance. Even so, effect sizes would be small.

It is also possible that the trials focused on regions of the brain suboptimal for this objective, and thus the authors "cannot rule out the possibility that stimulation of other prefrontal regions (such as the right hemispheric inferior frontal cortex or dorsolateral prefrontal cortex or parietal regions), multiple session tDCS or tDCS in combination with cognitive training could improve clinically or cognitive functions in ADHD."

As to concerns about safety, on the other hand, "stimulation was well-tolerated overall."

The authors concluded that based on current evidence, tDCS of the dorsolateral prefrontal cortex cannot yet be recommended as an alternative Neurotherapy for ADHD.

February 15, 2022

Rethinking First-Line ADHD Medication: Are Non-Stimulants Being Undervalued?

Stimulant medications have long been considered the default first-line treatment for attention-deficit/hyperactivity disorder (ADHD). Clinical guidelines, prescribing practices, and public narratives all reinforce the idea that stimulants should be tried first, with non-stimulants reserved for cases where stimulants fail or are poorly tolerated.

I recently partnered with leading ADHD researcher Jeffrey Newcorn for a Nature Mental Health commentary on the subject. We argue that this hierarchy deserves reexamination. It is important to note that our position is not anti-stimulant. Rather, we call into question whether the evidence truly supports treating non-stimulants as secondary options, and we propose that both classes should be considered equal first-line treatments.

What the Evidence Really Shows

Stimulants have earned their reputation as the go-to drug of choice for ADHD. They are among the most effective medications in psychiatry, reliably reducing core ADHD symptoms and improving daily functioning when properly titrated and monitored. However, when stimulant and non-stimulant medications are compared more closely, the gap between them appears smaller than commonly assumed.

Meta-analyses often report slightly higher average response rates for stimulants, but head-to-head trials where patients are directly randomized to one medication versus another frequently find no statistically significant differences in symptom improvement or tolerability. Network meta-analyses similarly show that while some stimulant formulations have modest advantages, these differences are small and inconsistent, particularly in adults.

When translated into clinical terms, the advantage of stimulants becomes even more modest. Based on existing data, approximately eight patients would need to be treated with a stimulant rather than a non-stimulant for one additional person to experience a meaningful benefit. This corresponds to only a 56% probability that a given patient will respond better to a stimulant than to a non-stimulant. This difference is not what we would refer to as “clinically significant.” 

How The Numbers Can Be Misleading

One reason non-stimulants may appear less effective is the way efficacy is typically reported. Most comparisons rely on standardized mean differences, a method of averages that may mask heterogeneity of treatment effects. In reality, ADHD medications do not work uniformly across patients.

For example, evidence suggests that response to some non-stimulants, such as atomoxetine, is bimodal: this means that many patients respond extremely well, while others respond poorly, with few in between. When this happens, average effect sizes can obscure the fact that a substantial subgroup benefits just as much as they would from a stimulant. In other words, non-stimulants are not necessarily less effective across the board, but that they are simply different in who they help.

Limitations of Clinical Trials

In our commentary, we also highlight structural issues in ADHD research. Stimulant trials are particularly vulnerable to unblinding, as their immediate and observable physiological effects can reveal treatment assignment, potentially inflating perceived efficacy. Non-stimulants, with slower onset and subtler effects, are less prone to this bias.

Additionally, many randomized trials exclude patients with common psychiatric comorbidities such as anxiety, depression, or substance-use disorders. Using co-diagnoses as exclusion criteria for clinical trials on ADHD medications is nonviable when considering the large number of ADHD patients who also have other diagnoses. Real-world data suggest that a large proportion of individuals with ADHD would not qualify for typical trials, limiting how well results generalize to everyday clinical practice.

Considering the Broader Impact

Standard evaluations of medication tolerability focus on side effects experienced by patients, but this narrow lens misses broader societal consequences. Stimulants are Schedule II controlled substances, which introduces logistical barriers, regulatory burdens, supply vulnerabilities, and administrative strain for both patients and clinicians.

When used as directed, stimulant medications do not increase risk of substance-use disorders (and, in fact, tend to reduce these rates); however, as ADHD awareness has spread and stimulants are more widely prescribed, non-medical use of prescription stimulants has become more widespread, particularly among adolescents and young adults. Non-stimulants do not carry these risks.

Toward Parallel First-Line Options

Non-stimulants are not without drawbacks themselves, however. They typically take longer to work and have higher non-response rates, making them less suitable in situations where rapid results are essential. These limitations, however, do not justify relegating them to second-line status across the board.

This is a call for abandoning a one-size-fits-all approach. Instead, future guidelines should present stimulant and non-stimulant medications as equally valid starting points, clearly outlining trade-offs related to onset, efficacy, misuse risk, and practical burden.

The evidence already supports this shift. The remaining challenge is aligning clinical practice and policy with what the data, and patient-centered care, are increasingly telling us.

January 8, 2026

Patient-Centered Outcomes Research Institute (PCORI) to Fund Landmark ADHD Medication Study

Today, most treatment guidelines recommend starting ADHD treatment with stimulant medications. These medicines often work quickly and can be very effective, but they do not help every child, and they can have bothersome side effects, such as appetite loss, sleep problems, or mood changes. Families also worry about long-term effects, the possibility of misuse or abuse, as well as the recent nationwide stimulant shortages. Non-stimulant medications are available, but they are usually used only after stimulants have not been effective.

This stimulant-first approach means that many patients who would respond well to a non-stimulant will end up on a stimulant medication anyway. This study addresses this issue by testing two different ways of starting medication treatment for school-age children with attention-deficit/hyperactivity disorder (ADHD). We want to know whether beginning with a non-stimulant medicine can work as well as the  “stimulant-first” approach, which is currently used by most prescribers.

From this study, we hope to learn:

  • Is starting with a non-stimulant medication “good enough” compared with starting with a stimulant?
    In other words, when we look at overall improvement in a child’s daily life, not just ADHD symptoms, does a non-stimulant-first approach perform similarly to a stimulant-first approach?
  • Which children do better with which approach?
    Children with ADHD are very different from one another. Some have anxiety, depression, learning problems, or autism spectrum conditions. We want to know whether certain groups of children benefit more from starting with stimulants, and others from starting with non-stimulants.
  • How do the two strategies compare for side effects, treatment satisfaction, and staying on medication?
    We will compare how often children stop or switch medications because of side effects or lack of benefit, and how satisfied children, parents, and clinicians are with care under each strategy.
  • What are the longer-term outcomes over a year?
    We are interested not only in short-term symptom relief, but also in how children are doing months later in school, at home, with friends, and emotionally.

Our goal is to give families and clinicians clear, practical evidence to support a truly shared decision: “Given this specific child, should we start with a stimulant or a non-stimulant?”

Who will be in the study?

We will enroll about 1,000 children and adolescents, ages 6 to 16, who:

  • Have ADHD and are starting or restarting medication treatment, and
  • Are being treated in everyday pediatric and mental health clinics at large children’s hospitals and health systems across the United States.

We will include children with common co-occurring conditions (such as anxiety, depression, learning or developmental disorders) so that the results reflect the “real-world” children seen in clinics, not just highly selected research volunteers.

How will the treatments be assigned?

This is a randomized comparative effectiveness trial, which means:

  • Each child will be randomly assigned (like flipping a coin) to one of two strategies:


    1. Stimulant-first strategy – the clinician starts treatment with a stimulant medication.
    2. Non-stimulant-first strategy – the clinician starts treatment with a non-stimulant medication.
  • Within the assigned class, the clinician and family still choose the specific medicine and dose, and can adjust treatment as they normally would. This keeps the study as close as possible to real-world practice.
  • The randomization is 1:1, so about half the participants will start with stimulants and half with non-stimulants.

Parents and clinicians will know which type of medicine the child is taking, as in usual care. However, the experts who rate how much each child has improved using our main outcome measure will not be told which treatment strategy the child received. This helps keep their ratings unbiased.

What will participants be asked to do?

Each family will be followed for 12 months. We will collect information at:

  • Baseline (before or just as medication is started)
  • Early follow-up (about weeks 3 and 6)
  • Later follow-up (about 3 months, 6 months, and 12 months)

At these times:

  • Parents will complete questionnaires about ADHD symptoms, behavior, emotions, and daily functioning at home and in the community.
  • Teachers will complete brief forms about the child’s behavior and performance at school.
  • Children and teens (when old enough) will complete age-appropriate questionnaires about their own mood, behavior, and quality of life.
  • A specially trained clinical rater, using all available information but blinded to treatment strategy, will give a global rating of how much the child has improved overall, not just in ADHD symptoms.

We will also track:

  • Medication changes (stopping, switching, or adding medicines)
  • Reasons for any changes (side effects, lack of benefit, or other reasons)
  • Any serious side effects or safety concerns

Data will be entered into a secure, HIPAA-compliant research database. Study staff at each site will work closely with families to make participation as convenient as possible, including offering flexible visit schedules and electronic options for completing forms when feasible.

How will we analyze the results?

Using standard statistical methods, we will:

  • Compare the overall improvement of children in the stimulant-first group versus the non-stimulant-first group after 12 months.
  • Look at differences in side effects, discontinuation rates, and treatment satisfaction between the two strategies.
  • Examine which child characteristics (such as age, sex, co-occurring conditions, and baseline severity) are linked to better results with one strategy versus the other.
  • Analyze long-term outcomes, including functioning at home, school, and with peers, and emotional well-being.

All analyses will follow the “intention-to-treat” principle, meaning we compare children based on the strategy they were originally assigned to, even if their medication is later changed. This mirrors real-world decision-making: once you choose a starting strategy, what tends to happen over time?

Why is this study necessary now?

This study addresses a critical, timely gap in ADHD care:

  • Guidelines are ahead of the evidence.
    Existing guidelines almost always recommend stimulants as the first-line medication, yet careful reviews of the evidence show that direct comparisons of stimulant-first versus non-stimulant-first strategies are limited. We do not have strong data to say that starting with stimulants is clearly superior for all children.
  • Real-world children are more complex than those in past trials.
    Most prior medication trials have excluded children with multiple conditions, serious family stressors, or other complexities that are very common in everyday practice. Our pragmatic, multi-site design will include these children and thus produce findings that are directly relevant to front-line clinicians and families.
  • Families and clinicians are asking for alternatives.
    Parents often express worries about stimulant side effects, long-term use, and stigma. Clinicians would like clearer guidance about when a non-stimulant is a reasonable first choice. At the same time, stimulant shortages and concerns about misuse and diversion have exposed the risks of relying almost entirely on one class of medications.
  • The timing is right to influence practice and policy.
    Our team includes parents, youth advocates, frontline clinicians, and national networks that link major children’s hospitals. These partners have helped shape the study from the beginning and will help interpret and share the results. This means that if starting with non-stimulants is found to be similarly effective and safer or more acceptable for some children, practice patterns and guidelines can change rapidly.

In short, this study is needed now to move ADHD medication decisions beyond “one-size-fits-all.” By rigorously comparing stimulant-first and non-stimulant-first strategies in real-world settings, and by focusing on what matters most to children and families overall functioning, side effects, and long-term well-being, we aim to give patients, parents, and clinicians the information they need to choose the best starting treatment for each child.

This project was conceived by Professor Stephen V. Faraone, PhD (SUNY Upstate Medical University, Department of Psychiatry, Syracuse, NY) and Professor Jeffrey H. Newcorn, MD (Icahn School of Medicine at Mount Sinai, Department of Psychiatry, New York, NY).   It will be conducted at nine sites across the USA.

January 2, 2026

Evidence-Based Interventions for ADHD

EBI-ADHD: 

If you live with ADHD, treat ADHD, or write about ADHD, you’ve probably run into the same problem: there’s a ton of research on treatments, but it’s scattered across hundreds of papers that don’t talk to each other.  The EBI-ADHD website fixes that. 

EBI-ADHD (Evidence-Based Interventions for ADHD) is a free, interactive platform that pulls together the best available research on how ADHD treatments work and how safe they are. It’s built for clinicians, people with ADHD and their families, and guideline developers who need clear, comparable information rather than a pile of PDFs. EBI-ADHD Database  The site is powered by 200+ meta-analyses covering 50,000+ participants and more than 30 different interventions.  These include medications, psychological therapies, brain-stimulation approaches, and lifestyle or “complementary” options. 

The heart of the site is an interactive dashboard.  You can: 

  1. Choose an age group: children (6–17), adolescents (13–17), or adults (18+). 
  1. Choose a time frame: results at 12, 26, or 52 weeks. 
  1. Choose whether to explore by intervention (e.g., methylphenidate, CBT, mindfulness, diet, neurofeedback) or by outcome (e.g., ADHD symptoms, functioning, adverse events), depending on what’s available. EBI-ADHD Database 

The dashboard then shows an evidence matrix: a table where each cell is a specific treatment–outcome–time-point combination. Each cell tells you two things at a glance: 

  1. How big the effect is, compared to placebo or another control (large benefit, small benefit, no effect, small negative impact, large negative impact). 
  1. How confident we can be in that result (high, moderate, low, or very low certainty).  

Clicking a cell opens more detail: effect sizes, the underlying meta-analysis, and how the certainty rating was decided. 

EBI-ADHD is not just a curated list of papers. It’s built on a formal umbrella review of ADHD interventions, published in The BMJ in 2025. That review re-analyzed 221 meta-analyses using a standardized statistical pipeline and rating system. 

The platform was co-created with 100+ clinicians and 100+ people with lived ADHD experience from around 30 countries and follows the broader U-REACH framework for turning complex evidence into accessible digital tools.  

Why it Matters 

ADHD is one of the most studied conditions in mental health, yet decisions in everyday practice are still often driven by habit, marketing, or selective reading of the literature. EBI-ADHD offers something different: a transparent, continuously updated map of what we actually know about ADHD treatments and how sure we are about it. 

In short, it’s a tool to move conversations about ADHD care from “I heard this works” to “Here’s what the best current evidence shows, and let’s decide together what matters most for you.”