January 14, 2022

How effective is transcranial direct current stimulation at improving response inhibition?

Inhibitory control is an essential cognitive control function whereby the prefrontal cortex blocks planned motor actions or interrupts motor actions already initiated by other parts of the brain. For example, someone might instinctually reach for a candy bar but then put it back upon thinking that eating it would conflict with a higher-level goal of cutting down on sugar consumption. Impairment of inhibitory control is a known characteristic of several psychiatric disorders, including ADHD.

Any generally safe treatment with the ability to at least partially reverse such impairment would therefore be useful. Researchers are currently experimenting with transcranial direct current stimulation, a non-invasive brain stimulation technique that uses a weak electrical current to stimulate specific regions of the brain.

What, then, do we know so far about its potential effectiveness for improving inhibitory control?

A team of experts at the University of Tübingen in Germany conducted a comprehensive search of the peer-reviewed medical literature to find out. They then performed a meta-analysis of 45 studies with a combined total of over 1,600 participants. All but four of the studies used sham or other active controls.

The overall meta-analysis found a significant but small improvement in response inhibition. But it also found evidence of publication bias. Adjusting for publication bias reduced the effect size in half, to a tiny but still significant improvement.

The meta-analysis relied on two behavioral tasks that require inhibitory control to measure response inhibition: the go-/no-task, and the stop-signal task. Separating these, there was no significant improvement in the go/no-go task performance. All the improvement was concentrated on the stop-signal task.

The authors noted, "A potential limitation of this meta-analysis is that we could not exhaustively model-dependent relationships between moderator variables (e.g., tDCS polarity and electrode placement)," and "Further high-quality studies are needed to investigate potential interactions between technical and functional parameters in tDCS research."

Philipp A.Schroeder, Tobias Schwippel, Ines Wolz, Jennifer Svaldi, "Meta-Analysis Of The Effects Of Transcranial Direct Current Stimulation On Inhibitory Control," BrainStimulation(2020),https://doi.org/10.1016/j.brs.2020.05.006.

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The Neurocognitive Roots of Boredom in ADHD: a Meta-Analysis

Boredom is more than just feeling restless or under-stimulated. It’s a negative emotional state that arises when activities feel meaningless or dull and, for those with ADHD, this negative emotional state might be markedly more intense. Researchers increasingly view boredom as functional: an internal signal pushing people to seek more rewarding and meaningful experiences. But for some, that signal becomes chronic and overwhelming.

People who are highly prone to boredom face a range of psychological and behavioral consequences, including anxiety, depression, difficulty identifying their own emotions (alexithymia), impulsivity, and physical complaints. These struggles often surface in harmful behaviors: overeating, substance use, compulsive internet use, and gambling.

For people with ADHD, boredom can cross into genuine distress. Many describe it as “torture” or “an itchy coat you can’t scratch”,  language that conveys not mild discomfort but an urgent, almost unbearable need to escape. This makes sense given that ADHD involves core difficulties with attention, arousal regulation, and motivation, all of which make sustained engagement harder and boredom far more likely.

The Study:

A recent meta-analysis of 18 studies involving more than 22,000 participants confirmed a moderately strong and consistent positive association (an overall effect size of r = 0.40) between ADHD and self-reported boredom. All but one study found significant results, and there was no evidence of publication bias.

“While the relationship between ADHD and boredom may seem obvious,” the authors state, “this has paradoxically led to the phenomenon being understudied.”

Despite how significant this connection appears to be, the researchers noted it has attracted surprisingly little scientific attention; a gap they attribute to a widespread assumption that boredom in ADHD is simply a byproduct of inattention or impulsivity, and therefore not worth studying on its own terms. They push back on that view, arguing that boredom may be a more fundamental part of the ADHD experience: a bridge between atypical brain function and the behavioral, emotional, and cognitive difficulties that shape long-term outcomes.

The Take-Away: 

Ultimately, addressing the profound boredom experienced by individuals with ADHD requires a multifaceted approach that goes beyond simply treating inattention. Researchers emphasize the need for rigorous studies to determine if stimulant medications actively reduce this intense boredom by repairing underlying brain mechanisms, rather than just as a side effect of improved focus. Beyond medication, tailored psychological therapies may offer promise; psychoeducation can help individuals reframe boredom as a biological signal rather than a personal failure or character flaw. 

Additionally, another approach suggests that rather than solely focusing on treating the individual, systemic issues must be addressed, such as the effects of low-stimulation environments. For example, prioritizing a better "person-environment fit" through smaller class sizes, flexible academic pacing, and/or offering highly stimulating, novel tasks, schools and workplaces can offer meaningful relief from the chronic distress of ADHD-related boredom. 

May 11, 2026

Early Skull Fusion in Infants Linked to Higher ADHD Risk

A new study from Japan suggests that infants born with craniosynostosis are significantly more likely to be diagnosed with ADHD later in childhood. Craniosynostosis is a condition in which the bony plates of the skull fuse prematurely, leading to increased intracranial pressure. 

The Background:

Craniosynostosis affects roughly one in every 2,000 births. When the skull’s natural seams close prematurely, it can restrict brain growth and increase intracranial pressure, potentially reducing blood flow to the brain. Because the condition is relatively rare, it has been difficult to study at scale until now. 

The Study:

To overcome this, researchers tapped into a large Japanese insurance database compiled by JMDC, Inc., which holds records on around 20 million people, or about 15% of Japan’s population. Drawing on two decades of data, the team tracked over 338,000 mother-child pairs. Children with related genetic syndromes or chromosomal conditions such as Down syndrome were excluded to keep the focus on craniosynostosis itself. 

Of the children studied, around 1,145 had craniosynostosis, and 7,325 were diagnosed with ADHD. After accounting for factors like sex, birth year, maternal age, mental health history, pregnancy infections, and birth complications, children with craniosynostosis were found to have roughly 2.4 times the risk of a subsequent ADHD diagnosis compared to those without it. 

To test whether shared family genetics or home environment might be driving the association rather than the skull condition itself, the researchers conducted a separate analysis among siblings. The elevated risk remained at 2.2 times. The consistency of the finding across both analyses strengthens the case for a genuine biological link. 

The Results:

The results point to raised intracranial pressure and restricted cerebral blood flow as plausible mechanisms, though the study’s observational design means causation cannot be confirmed. Ultimately, these findings highlight the need for proactive, long-term care strategies for those born with craniosynostosis. By establishing a solid link between premature skull fusion and a significantly higher risk of ADHD, the research demonstrates that medical care for this condition should not end once the skull's physical structure is addressed.

The Takeaway:

Pediatricians, neurologists, and parents can use this data to implement early, routine behavioral and developmental screening for these children as they grow. This additional support would ensure that those who do develop ADHD can receive timely interventions, educational aids, and therapies, ultimately improving their long-term developmental outcomes.

Population Study Indicates ADHD Drug Treatment May Reduce Contact with Child Welfare Services

Children and adolescents with ADHD come into contact with child welfare services (CWS) far more often than their peers. There are many contributing factors to consider, including the fact that hyperactivity and impulsivity frequently lead to behaviors that are considered disruptive and cause academic and social difficulties. Many of these children are also growing up in households marked by parental conflict and/or single-parent arrangements.  All of these circumstances can compound vulnerability and, historically, increase the likelihood of CWS involvement.

Background: 

In Norway, Child Welfare Services operate at the municipal level and are legally required in every local authority. Their scope spans investigation, family support, and, where necessary, out-of-home placement and ongoing monitoring. Grounds for intervention include abuse, neglect, behavioral or psychosocial difficulties, and inadequate care-giving. Norwegian CWS works closely with health, education, and social services and places a strong emphasis on keeping families together. Compared with systems in countries such as the United States, Poland, Romania, and the Czech Republic, the Norwegian approach sets a lower bar for intervention and leans toward home-based support, while setting a higher bar for out-of-home placements. This model is shared by other Nordic countries, as well as Germany and the United Kingdom. 

Research into whether ADHD medication affects child welfare caseloads is remarkably sparse. A single Danish study previously found that medication treatment accounted for much of an observed decline in foster care cases, but no study had examined medication’s broader impact on CWS involvement, covering both supportive interventions and out-of-home placements. 

Norway’s universal single-payer health system and comprehensive national registers make population-wide research of this kind feasible. Drawing on these resources, a Norwegian research team set out to test whether ADHD medication reduces children’s contact with CWS and their need for out-of-home placement. 

The Study:

This study included all 5,930 children and adolescents aged 5 to 14 who received a clinical ADHD diagnosis from Child and Adolescent Mental Health Services between 2009 and 2011. Each was followed for up to 4 years post-diagnosis, the upper age limit being 18, at which point CWS jurisdiction ends. This group was compared with more than 53,000 peers who had no CWS contact during the same period. 

The results showed a meaningful, though not dramatic, association between medication and reduced CWS contact. At one year, treated children had approximately 7% fewer contacts with CWS; by two years, that figure had risen to around 12%. The effect then narrowed, settling at roughly 7–8% reductions at the three- and four-year marks. 

The picture for out-of-home placements is considerably less convincing. The research team highlighted a 3% reduction at two-year follow-up, but this finding barely crossed the threshold of statistical significance, and no effect was observed at the one-, three-, or four-year follow-up points. 

The Take-Away:

The authors concluded that pharmacological treatment for ADHD is associated with reductions in both supportive CWS services and out-of-home placements among children affected by clinicians’ prescribing decisions in Norway. A more cautious reading of the same data, however, would emphasize an overall reduction in CWS contact of roughly 8%, while treating the out-of-home placement finding as, at best, inconclusive. 

May 4, 2026