January 27, 2025

Norwegian Nationwide Population Study Finds No ADHD- or ASD- Related Benefits From Eating Organic Food During Pregnancy

Background:

Organic farming aims to protect biodiversity, promote animal welfare, and avoid using pesticides and fertilizers made from petrochemicals. Some pesticides are designed to target insects’ nervous systems but can also affect brain development and health in larger animals, including humans.

Many people believe organic food is healthier than conventionally produced food, which might be true for certain foods and health factors. But does eating organic food during pregnancy impact the chances of a child developing ADHD or autism spectrum disorder (ASD)?

In Norway, researchers can use detailed national health records to study these connections on a population-wide level, thanks to the country’s single-payer healthcare system and national registries.

Method:

The Norwegian Mother, Father, and Child Cohort Study (MoBa) invites parents to participate voluntarily and has a 41% participation rate. The study includes:

  • 114,500 children
  • 95,200 mothers
  • 75,200 fathers

For this research, a team tracked 40,707 mother-child pairs from children born between 2002 and 2009. They used questionnaires to measure how much organic food mothers consumed during pregnancy. ADHD and ASD symptoms in children were assessed using validated rating scales.

The final analysis included:

  • 40,586 pairs for ADHD symptoms
  • 40,117 pairs for ASD symptoms

The researchers adjusted for factors like maternal age, education, previous pregnancies, BMI before pregnancy, smoking and alcohol use during pregnancy, birth year and season, and the child’s sex.

Key Findings:
  • There was a weak connection between higher organic food consumption and fewer ADHD symptoms in children. However, this link disappeared when maternal ADHD symptoms were considered (31,411 pairs) or when the analysis was limited to siblings (5,534 pairs).
  • Similarly, weak associations between organic food and fewer ASD symptoms disappeared when focusing on siblings (4,367 pairs).
Conclusion:

The researchers concluded that eating organic food during pregnancy has no meaningful effect on the likelihood of a child developing ADHD or ASD. They stated, “The results do not indicate any clinically significant protective or harmful effects of eating organic food during pregnancy on symptoms of ADHD and ASD in the offspring. Based on these findings, we do not recommend any specific advice regarding intake of organic food during pregnancy.”

Johanne T. Instanes, Berit S. Solberg, Liv G. Kvalvik, Kari Klungsøyr, Maj‑Britt R. Posserud, Catharina A. Hartman, and Jan Haavik, “Organic food consumption during pregnancy and symptoms of neurodevelopmental disorders at 8 years of age in the offspring: the Norwegian Mother, Father and Child Cohort Study (MoBa),” BMC Medicine (2024), 22:482, https://doi.org/10.1186/s12916-024-03685-5.

Related posts

Do Some Foods Cause ADHD? Does Dieting Help?

Do Some Foods Cause ADHD? Does Dieting Help?

If we are to read what we believe on the Internet, dieting can cure many of the ills faced by humans. Much of what is written is true. Changes in dieting can be good for heart disease, diabetes, high blood pressure, and kidney stones to name just a few examples. But what about ADHD? Food elimination diets have been extensively studied for their ability to treat ADHD. They are based on the very reasonable idea that allergies or toxic reactions to foods can have effects on the brain and could lead to ADHD symptoms.

Although the idea is reasonable, it is not such an easy task to figure out what foods might cause allergic reactions that could lead to ADHD symptoms. Some proponents of elimination diets have proposed eliminating a single food, others include multiple foods, and some go as far as to allow only a few foods to be eaten to avoid all potential allergies. Most readers will wonder if such restrictive diets, even if they did work, are feasible. That is certainly a concern for very restrictive diets.

Perhaps the most well-known ADHD diet is the Feingold diet(named after its creator). This diet eliminates artificial food colorings and preservatives that have become so common in the western diet. Some have claimed that the increasing use of colorings and preservatives explains why the prevalence of ADHD is greater in Western countries and has been increasing over time. But those people have it wrong. The prevalence of ADHD is similar around the world and has not been increasing over time. That has been well documented but details must wait for another blog.

The Feingold and other elimination diets have been studied by meta-analysis. This means that someone analyzed several well-controlled trials published by other people. Passing the test of meta-analysis is the strongest test of any treatment effect. When this test is applied to the best studies available, there is evidence that the exclusion of fool colorings helps reduce ADHD symptoms. But more restrictive diets are not effective. So removing artificial food colors seems like a good idea that will help reduce ADHD symptoms. But although such diets ‘work’, they do network very well. On a scale of one to 10where 10 is the best effect, drug therapy scores 9 to 10 but eliminating food colorings scores only 3 or 4. Some patients or parents of patients might want this diet change first in the hopes that it will work well for them. That is a possibility, but if that is your choice, you should not delay the more effective drug treatments for too long in the likely event that eliminating food colorings is not sufficient. You can learn more about elimination diets from Nigg, J. T., and K.Holton (2014). "Restriction and elimination diets in ADHD treatment."Child Adolesc Psychiatr Clin N Am 23(4): 937-953.

Keep in mind that the treatment guidelines from professional organizations point to ADHD drugs as the first-line treatment for ADHD. The only exception is for preschool children where medication is only the first-line treatment for severe ADHD; the guidelines recommend that other preschoolers with ADHD be treated with non-pharmacologic treatments, when available. You can learn more about non-pharmacologic treatments for ADHD from a book I recently edited: Faraone, S. V. &Antshel, K. M. (2014). ADHD: Non-Pharmacologic Interventions. Child AdolescPsychiatr Clin N Am 23, xiii-xiv.

March 20, 2021

Is There Any Hard Evidence in Support of Homeopathic Remedies for ADHD?

Is there any hard evidence in support of homeopathic remedies for ADHD?

According to Vox, "Homeopathy is a $1.2 billion industry in the US alone, used by an estimated 5 million adults and 1 million kids. It's become such a staple of America's wellness industry that leading brands such as Boiron and Hyland's are readily available at high-end health-focused chains like Whole Foods and sprouts, supermarkets like Ralph's, and superstores such as Walmart."

Yet, this highly profitable "wellness" industry has shown little to no interest in supporting randomized clinical trials (RCTs) to test the efficacy and safety of its products.

In a team of Italian physicians, Rana comprehensive search of the medical literature and found only nine RCTs exploring the efficacy and safety of homeopathic remedies for psychiatric disorders that met the selection criteria.

Only two of these RCTs addressed efficacy for ADHD, with a combined 99 participants. Neither reported any significant effect.

Combining them into a small meta-analysis likewise found no significant effect.

But that's not all. According to the study authors, "The paucity of published trials does not allow a reliable estimate of publication bias, which would require a larger number of studies. This is a major issue since it has been reported that, among completed trials of homeopathy registered on ClinicalTrials.gov, only 46% were published within 2 years of completion, and among these, 25% altered or changed their primary outcomes. It is, therefore, possible that the results of the present meta-analysis are distorted because of selective publication."

The authors conclude, "The most surprising result of this meta-analysis is the paucity of available data from RCTs," and "Based on the very few available trials, homeopathy did not produce any relevant effect on symptoms of ADHD ... Ethical considerations should therefore prevent clinicians from recommending HRs [homeopathic remedies], which have a cost either for patients or for health care systems, until when a sufficient amount of solid evidence becomes available."

January 8, 2022

Is There Any Relationship Between Artificial Food Colors and ADHD?

Is There Any Relationship Between Artificial Food Colors and ADHD?

Several meta-analyses have assessed this question by computing the Standardized Mean Difference or SMD statistic. The SMD is a measure that allows us to compare different studies. For context, the effect of stimulant medication for treating ADHD is about 0.9.  SMDs less than 0.3 are considered low, between 0.3 to 0.6 medium, and anything greater than high.


A 2004 meta-analysis combined the results of fifteen studies with a total of 219 participants and found a small association(SMD = .28, 95% CI .08-.49) between consumption of artificial food colors by children and increased hyperactivity. Excluding the smallest and lowest quality studies further reduced the SMD to .21, and a lower confidence limit of .007 also made it barely statistically significant. Publication bias was indicated by an asymmetric funnel plot. No effort was made to correct the bias.


A 2012 meta-analysis by Nigg et al. combined twenty studies with a total of 794 participants and again found a small effect size (SMD =.18, 95% CI .08-.29). It likewise found evidence of publication bias. Correcting for the bias led to a tiny effect size at the outer margin of statistical significance (SMD = .12, 95% CI .01-.23). Restricting the pool to eleven high-quality studies with 619 participants led to a similarly tiny effect size that fell just outside the 95% confidence interval (SMD = .13, CI =0-.25, p = .053). The authors concluded, "Overall, a mixed conclusion must be drawn. Although the evidence is too weak to justify action recommendations absent a strong precautionary stance, it is too substantial to dismiss."

In 2013 a European ADHD Guidelines Group consisting of 21 researchers (Sonuga-Barke et al.) performed a systematic review and meta-analysis that examined the efficacy of excluding artificial colors from the diets of children and adolescents as a treatment for ADHD. While many interventions showed benefits in unblinded assessments, only artificial food color exclusion and, to a lesser extent, free fatty acid supplementation remained effective under blinded conditions. The findings suggest that eliminating artificial food dyes may meaningfully reduce ADHD symptoms in some children, though it should be noted that the positive results were mostly seen in children with other food sensitivities.


The research to date does suggest a small effect of artificial food colors in aggravating symptoms of hyperactivity in children, and a potential beneficial effect of excluding these substances from the diets of children and adolescents, but the evidence is not very robust. More studies with greater numbers of participants, and better control for the effects of ADHD medications, will be required for a more definitive finding.


In the meantime, given that artificial food colors are not an essential part of the diet, parents could consider excluding them from their children's meals, since doing so is risk-free, and the cost (reading labels) is negligible.

June 22, 2021

Exercise as an ADHD Intervention: What Two Recent Meta-Analyses Tell Us

Exercise has attracted growing attention as an intervention for ADHD. As a potential treatment option for ADHD, it is, of course, highly appealing because it can be low- to no-cost, widely accessible, and free of the side effects that can accompany medication. From previous studies, we know that certain types of exercise may be more effective than others, but do we actually know enough for clinicians to prescribe physical activity as a treatment for ADHD? 

The First Study: Effects on Core ADHD Symptoms 

Despite encouraging findings in individual studies, researchers have lacked clear guidance on which types of exercise work best, at what intensity, and for how long. A meta-analysis by Chen et al. set out to address this by pooling data from 20 randomized controlled trials (RCTs) involving 841 children and adolescents aged 4–18, all of which compared exercise interventions against non-exercising control groups. 

The results were cautiously optimistic. Across standardized symptom scales, exercise produced a small improvement in ADHD symptoms overall. Objective cognitive tests showed a moderate improvement. Emotional and behavioral outcomes, however, showed no significant change. 

To understand what was driving differences between studies, the researchers broke results down by exercise type. Therapeutic and alternative exercises (targeted movements and specific techniques such as those prescribed by physical therapists) were associated with moderate symptom improvements. Mind-body practices (such as yoga or tai chi) showed small-to-moderate gains. Conventional aerobic exercise yielded smaller effects, while skill-based competitive sports showed no measurable benefit. Notably, the variability between individual studies remained high throughout, meaning these categories should be interpreted with some caution. 

Results:

The authors recommend that clinicians and parents consider incorporating therapeutic or alternative exercise sessions twice a week, each lasting 60–90 minutes, as a supplemental strategy alongside existing ADHD treatment. They stop short of calling this definitive, noting that future research should clarify how exercise produces its effects and how it might best be combined with medication or behavioral therapy. 

The Second Study: Effects on Inhibitory Control 

A second meta-analysis, by Zhang et al., zoomed in on a specific and particularly relevant cognitive challenge in ADHD: inhibitory control. Inhibitory control refers to the ability to suppress impulsive responses and tune out irrelevant distractions. This capacity underlies much of the restlessness, interrupting, and difficulty staying on task that characterize the condition. 

This analysis drew on 34 studies with over 1,300 participants spanning all age groups, making it broader in scope than the Chen et al. review. Overall, exercise was associated with a moderate improvement in inhibitory control. When the analysis was restricted to RCTs alone, this finding held up. When studies with a high risk of bias were excluded, however, the effect size dropped to small-to-moderate. 

One notable null result: three studies that used EEG to measure brain activity during inhibitory tasks found no significant effects on the neural signatures most closely tied to this process. This suggests exercise may influence behavior without necessarily changing the underlying brain mechanisms researchers expected, or that current methods aren't yet sensitive enough to detect such changes. 

The dosing question produced some of the more practically useful findings. Single exercise sessions yielded only borderline small improvements. Sustained exercise programs, by contrast, showed moderate improvements, and programs with sessions three times per week produced large gains and had the strongest effect between the two meta-analyses. Exercise intensity and total program duration, perhaps interestingly, were not significant factors. 

Results: 

The authors are measured in their conclusions: exercise shows a real but modest benefit for inhibitory control, and frequency appears to matter more than intensity. They caution against overstating the case for exercise as treatment for ADHD overall, as it did not significantly affect hyperactivity or impulsivity as standalone outcomes, and its neural effects remain unclear. 

The Broader Picture

Ultimately, these two meta-analyses support exercise as a meaningful supplemental intervention for ADHD, particularly for attention and cognitive control, while urging realistic expectations. Neither suggests exercise should replace established treatments. Both are limited by high variability across the underlying studies, and both call for better-designed research to sharpen the guidance available to clinicians and families. 

 

 

 

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.