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Inflammatory bowel disease (IBD) consists of 2 main subtypes: Crohn’s disease and ulcerative colitis. Typical symptoms include abdominal pain, diarrhea, and rectal bleeding. Both are incurable, increase the risk of colorectal cancer, and often affect other organs as well.
A single earlier study suggested a weak link between childhood-onset IBD and ADHD.
A Danish research team used its country’s national registers – based on a single-payer national health insurance system that encompasses virtually the entire population – to include all 3,559 patients diagnosed with pediatric-onset IBD from 1998 through 2018.
The team then matched these individuals five-to-one on age, age of diagnosis, year of diagnosis, sex, municipality of residence, and time period, with 17,795 individuals from the same pool who were free of IBD.
ADHD was identified based on two criteria: clinical diagnoses in patient records, and methylphenidate stimulant prescriptions in the medications register.
Overall, the team found no significant association between pediatric-onset IBD and ADHD. The same was true for both Crohn’s disease and ulcerative colitis.
There were no differences in outcomes for boys or girls.
There was also no significant association found using only ADHD diagnoses or only methylphenidate prescriptions.
Among children and adolescents with IBD onset under age 14, there was a borderline significant association, but it was a negative one: They were less likely to subsequently be clinically diagnosed with ADHD or to receive prescriptions for methylphenidate.
The team concluded, “Remarkably, we found a reduced risk of receiving methylphenidate and being diagnosed with ADHD, which merits further investigation.”
Rebecca Kristine Kappel, Tania Hviid Bisgaard, Gry Poulsen, and Tine Jess, “Risk of Anxiety, Depression, and Attention-Deficit/ Hyperactivity Disorder in Pediatric Patients With Inflammatory Bowel Disease: A Population-Based Cohort Study,” Clinical and Translational Gastroenterology (2024), 15:e00657, https://doi.org/10.14309/ctg.0000000000000657.
In December 2016, the U.S. Food and Drug Administration (FDA) warned “that repeated or lengthy use of general anesthetic and sedation drugs during surgeries or procedures in children younger than 3 years or in pregnant women during their third trimester may affect the development of children’s brains.” The FDA adds, “Health care professionals should balance the benefits of appropriate anesthesia against the potential risks, especially for procedures lasting longer than 3 hours or if multiple procedures are required in children under 3 years,” and “Studies in pregnant and young animals have shown that using these drugs for more than 3 hours caused widespread loss of brain nerve cells.”
That raises a concern that such exposure could lead to increased risk of psychiatric disorders, including ADHD.
Noting “There are inconsistent reports regarding the association between general anesthesia and adverse neurodevelopmental and behavioral disorders in children,” a South Korean study team conducted a nationwide population study to explore possible associations through the country’s single-payer health insurance database that covers roughly 97% of all residents.
The team looked at the cohort of all children born in Korea between 2008 and 2009, and followed them until December 31, 2017. They identified 93,717 children in this cohort who during surgery received general anesthesia with endotracheal intubation (a tube inserted down the trachea), and matched them with an equal number of children who were not exposed to general anesthesia.
The team matched the unexposed group with the exposed group by age, sex, birth weight, residential area at birth, and economic status.
They then assessed both groups for subsequent diagnoses of ADHD.
In general, children exposed to general anesthesia were found to have a 40% greater risk of subsequently being diagnosed with ADHD than their unexposed peers.
This effect was found to be dose dependent by several measures:
All three measures were highly significant.
The authors concluded, “exposure to general anesthesia with ETI [endotracheal intubation] in children is associated with an increased risk of ADHD … We must recognize the possible neurodevelopmental risk resulting from general anesthesia exposure, inform patients and parents regarding this risk, and emphasize the importance of close monitoring of mental health. However, the risk from anesthesia exposure is not superior to the importance of medical procedures. Specific research is needed for the development of safer anesthetic drugs and doses.”
Although ADHD was conceived as a childhood disorder, we now know that many cases persist into adulthood. My colleagues and I charted the progression of ADHD through childhood, adolescence, and adulthood in our "Primer" about ADHD,http://rdcu.be/gYyV. Although the lifetime course of ADHD varies among adults with the disorder, there are many consistent themes, which we described in the accompanying infographic. Most cases of ADHD startin uterobefore the child is born. As a fetus, the future ADHD person carries versions of genes that increase the risk for the disorder. At the same time, they are exposed to toxic environments. These genetic and environmental risks change the developing brain, setting the foundation for the future emergence of ADHD.
In preschool, early signs of ADHD are seen in emotional lability, hyperactivity, disinhibited behavior, and speech, language, and coordination problems. The full-blown ADHD syndrome typically occurs in early childhood, but can be delayed until adolescence. In some cases, the future ADHD person is temporarily protected from the emergence of ADHD due to factors such as high intelligence or especially supportive family and/or school environments. But as the challenges of life increase, this social, emotional, and intellectual scaffolding is no longer sufficient to control the emergence of disabling ADHD symptoms. Throughout childhood and adolescence, the emergence and persistence of the disorder are regulated by additional environmental risk factors such as family chaos along with the age-dependent expression of risk genes that exert different effects at different stages of development. During adolescence, most cases of ADHD persist and by the teenage years, many youths with ADHD have onset with a mood, anxiety, or substance use disorder. Indeed, parents and clinicians need to monitor ADHD youth for early signs of these disorders. Prompt treatment can prevent years of distress and disability. By adulthood, the number of comorbid conditions has increased, including obesity, which likely has effects on future medical outcomes.
The ADHD adult tends to be very inattentive by showing fewer symptoms of hyperactivity and impulsivity. They remain at risk for substance abuse, low self-esteem, occupational failure, and social disability, especially if they are not treated for the disorder. Fortunately, there are several classes of medications available to treat ADHD that are safe and effective. And the effects of these medications are enhanced by cognitive behavior therapy, as I've written about in prior blogs.
Youths with disabilities face varying degrees of social exclusion and mental, physical, and sexual violence.
A Danish researcher used the country's extensive national registers to explore reported sexual crimes against youths across the entire population. Of 679,683 youths born from 1984to 1994 and between the ages of seven and eighteen, 8,039 (1.2 percent) were victims of at least one reported sex crime.
The sexual offenses in question included rape, sexual assault, sexual exploitation, incest, and indecent exposure. Sexual assault encompassed both intercourse/penetration without consent or engaged in with a youth not old enough to consent (statutory rape).
The study examined numerous disabilities, including ADHD, which was the most common one. It also performed a regression analysis to tease out other covariants, such as parental violence, parental inpatient mental illness, parental suicidal behavior or alcohol abuse, parental long-term unemployment, family separation, and children in public care outside the family.
In the raw data, youths with ADHD were 3.7 times more likely to be a victim of sexual crimes than normally developing youths. That was roughly equal to the odds for youths with an autism spectrum disorder or mental retardation, but considerably higher than for blindness, stuttering, dyslexia, and epilepsy (all roughly twice as likely to be victims of such crimes), and even higher than for the loss of hearing, brain injury, or speech or physical disabilities.
Looking at covariate, family separation, having a teenage mother, or being in public care almost doubled the risk of being a victim of sexual crimes. Parental violence or parental substance abuse increased the risk by 40 percent, and parental unemployment for over 21 weeks increased the risk by 30 percent. Girls were nine times more likely to be victimized than boys. Living in a disadvantaged neighborhood made no difference, and living in immigrant neighborhoods actually reduced the odds of being victimized by about 30 percent.
After adjusting for other risk factors, youths with ADHD were still almost twice as likely to be victims of reported sex crimes than normally developing youths. All other youths with disabilities registered significantly lower levels of risk after adjusting for other risk factors: for those who were blind, 60 percent higher risk; for those with autism, hearing loss, or epilepsy, 40 percent higher risk. Communicative disabilities - speech disability, stuttering, and dyslexia - actually turned out to have protective effects.
This points to a need to be particularly vigilant for signs of sexual abuse among youths with ADHD.
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.”
Children and adolescents with ADHD tend to be less active and more sedentary than their typically developing peers. This is concerning, since physical activity benefits mental, physical, and social development. For youth with ADHD, being active can improve symptoms like inattention, working memory, and inhibitory control.
A major barrier to physical activity for children and adolescents with ADHD is limited motor competence. This stems from challenges in developing basic motor skills and more complex abilities needed for sports and advanced movements.
Difficulties in developing fundamental movement skills – such as locomotor (running, jumping), object-control (throwing, catching), and stability skills (balancing, turning) – can reduce motor competence and limit physical activity. These basic movements are learned and refined with practice and age, not innate abilities.
To date, research on the link between ADHD and motor competence has remained inconclusive. This systematic review and meta-analysis by a Spanish research team therefore aimed to determine whether children and adolescents with ADHD differ in motor competence from those with typical development (TD).
Studies had to include children and adolescents diagnosed with ADHD. They had to involve a full motor assessment battery, not just one test, and present motor competence data for both ADHD and TD groups.
The team excluded studies involving participants with other neurodevelopmental disorders or cognitive impairments, unless separate data for the ADHD subgroup were reported.
Meta-analysis of six studies combining 323 children and adolescents found that typically developing individuals were twelve times more likely to score in the 5th percentile of the Movement Assessment Battery for Children as their peers diagnosed with ADHD. They were also three times more likely to score in the 15th percentile (five studies, 289 participants). Results were consistent across the studies (low heterogeneity). All included studies were randomized.
Meta-analysis of five studies totaling 198 participants using the Test of Gross Motor Development reported significant deficits in both locomotor skills and object control skills among children and adolescents diagnosed with ADHD relative to their typically developing peers. In this case, however, results were inconsistent across studies (very high heterogeneity), and one of the studies was unrandomized. Because the team published only unstandardized mean differences, there was no indication of effect sizes.
Meta-analysis of two studies encompassing 164 participants using the Bruininks-Oseretsky Test of Motor Proficiency similarly yielded significant deficits among children and adolescents diagnosed with ADHD relative to their typically developing peers, but in this case with low heterogeneity. Notably, one of the two studies was not randomized.
Moreover, the team made no assessment of publication bias.
The team concluded, “The findings of this review indicate that children and adolescents with ADHD show significantly lower levels of motor competence compared to their TD peers. This trend was evident across a range of validated assessment tools, including the MABC, BOT, TGMD, and other standardized test batteries. Future research should aim to reduce methodological heterogeneity and further investigate the influence of factors such as ADHD subtypes and comorbid conditions on motor development trajectories.”
However, without a publication bias assessment, reliance on unrandomized studies in two of the tests, no indication of effect size in the same two tests, and small sample sizes, these results are at best suggestive, and will require further research to confirm.
Executive function impairment is a key feature of ADHD, with its severity linked to the intensity of ADHD symptoms. Executive function involves managing complex cognitive tasks for organized behavior and includes three main areas: inhibitory control (suppressing impulsive actions), working memory (holding information briefly), and cognitive flexibility (switching between different mental tasks). Improving executive functions is a critical objective in the treatment of ADHD.
Amphetamines and methylphenidate are commonly used to treat ADHD, but can cause side effects like reduced appetite, sleep problems, nausea, and headaches. Long-term use may also lead to stunted growth and cardiovascular issues. This encourages the search for non-invasive methods to enhance executive function in children with ADHD.
Neurological techniques like neurofeedback and transcranial stimulation are increasingly used to treat children with neurodevelopmental disorders. Neurofeedback is the most adopted method; it is noninvasive and aims to improve brain function by providing real-time feedback on brainwave activity so participants can self-regulate targeted brain regions.
The systematic search and meta-analysis examined children and adolescents aged 6–18 with ADHD. It included randomized and non-randomized controlled trials, as well as quasi-experimental studies that reported statistical data such as participant numbers, means, and standard deviations. Studies were required to use validated measures of executive function, including neurocognitive tasks or questionnaires. They also had to have control groups.
A meta-analysis of ten studies (539 participants) found a small-to-medium improvement in inhibitory control after neurofeedback training, with no publication bias and minimal study heterogeneity*. Long-term treatment (over 21 hours) showed benefits, while short-term treatment did not. However, publication bias was present in the long-term treatment studies and was not addressed.
A meta-analysis of seven studies with 370 children and adolescents found a small-to-medium improvement in working memory after neurofeedback, with no publication bias overall but high heterogeneity. A dose-response effect was observed: treatments over 21 hours showed benefits, while shorter ones did not. However, publication bias was present in the long-term treatment studies and was not addressed.
The study team also looked at sustained effects six months to a year after conclusion of training. Meta-analysis of two studies totaling 131 participants found a sustained small-to-medium improvement in inhibitory control, with negligible heterogeneity. Meta-analysis of three studies combining 182 participants found a sustained medium improvement in working memory, with moderate heterogeneity and no sign of publication bias.
The team concluded, “NFT is an effective intervention for improving executive function in children with ADHD, specifically inhibitory control and working memory. This approach demonstrates a more pronounced impact on working memory when extended beyond 1000 min [sic], with inhibitory control following closely behind. Furthermore, the evidence suggests that NFT may have sustained effects on both working memory and inhibitory control. Given the relatively small number of studies assessing long-term effects and the potential for publication bias, further research is necessary to confirm these effects.”
Moreover, because 1) RCTs are the gold standard, and the meta-analyses combined RCTs with non-RCTs, and 2) data from neurocognitive tasks was combined with data from more subjective and less accurate questionnaires, these meta-analysis results should be interpreted with further caution.
*Heterogeneity refers to the rate of variation between individual study outcomes. High heterogeneity means that there was substantial variation in the results. When a meta-anaylysis has high heterogeneity, it suggests that the studies differ significantly in their populations, methods, interventions, or outcomes, making the combined result much less reliable.
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