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June 22, 2021
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.
Joel T. Nigg, Kara Lewis, Tracy Edinger, Michael Falk, “Meta-Analysis of Attention-Deficit/Hyperactivity Disorder attention-Deficit/Hyperactivity Disorder Symptoms, Restriction Diet, and synthetic Food Color Additives,” Journal of The American Academy of Child & Adolescent Psychiatry (2012), Vol.51, No. 1, 86-97.David W. Schab and Nhi-Ha T. Trinh, “Do Artificial FoodColors Promote Hyperactivity in Children with Hyperactive Syndromes? Aneta-Analysis of Double-Blind Placebo-Controlled Trials,” Developmental and behavioral Pediatrics(2004), Vol. 25, No. 6, 423-434.Edmund J.S. Sonuga-Barke et al., “NonpharmacologicalInterventions for ADHD: Systematic Review and Meta-Analyses of RandomizedControlled Trials of Dietary and Psychological Treatments,” American Journal of Psychiatry(2013), 170:275-289.
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.
Mindfulness has been defined as “intentionally directing attention to present moment experiences with an attitude of curiosity and acceptance.” Mindfulness-based interventions (MBIs) aim to improve mindfulness skills.
A newly-published meta-analysis of randomized controlled trials (RCTs) by a team of British neurologists and psychiatrists explores the effectiveness of MBIs in treating a variety of mental health conditions in children and adolescents. Among those conditions is the attention deficit component of ADHD.
A comprehensive literature search identified studies that met the following criteria:
1) The effects of mindfulness were compared against a control condition – either no contact, waitlist, active, or attention placebo. The waitlist means the control group receives the same treatment after the study concludes. Active control means that a known, effective treatment (as opposed to a placebo) is compared to an experimental treatment. Attention placebo means that controls receive a treatment that mimics the time and attention received by the treatment group but is believed not to have a specific effect on the subjects. Participants were randomly assigned to the control condition.
2) The MBI was delivered in more than one session by a trained mindfulness teacher, involved sustained meditation practice, and it was not mixed in with another activity such as yoga.
Eight studies evaluating attention deficit symptoms, with a combined total of 1,158 participants, met inclusion criteria. The standardized mean difference (SMD) was 0.19, with a 95% confidence range of 0.04 to 0.34 (p = .02). That indicates a small effect size for MBIs in reducing attention deficit symptoms. Heterogeneity was low (I2 = 35, p =.15), and the Egger test showed little sign of publication bias (p = 0.42).
When looking only at studies with active controls, five studies with a total of 787 participants yielded an SMD of 0.13, with a 95% confidence interval of -0.01 to 0.28 (p = .06), indicating a tiny effect size that failed to reach significance. Active controls most commonly received health education, with a few receiving social responsibility training or Hatha yoga.
Overall, this meta-analysis suggests limited effectiveness, especially when compared with active controls. If MBIs are effective for ADHD, their effect on symptoms is very small. Thus, such treatments should not be used in place of the many well-validated, evidenced-based therapies available. Whether longer periods of MBI (training times varied between 2 and 18 hours spread out over 2 to 24 weeks) might result in greater effect sizes remains unexplored
After noting that the association between ADHD and obesity has been called into question because of small sample sizes, wide age ranges, self-reported assessments, and inadequate attention to potential confounders, an Israeli study team set out "to assess the association between board-certified psychiatrist diagnoses of ADHD and measured adolescent BMI [body mass index] in a nationally represented sample of over one million adolescents who were medically evaluated before mandatory military service."
The team distinguished between severe and mild ADHD. It also focused on a single age group.
All Israelis are subject to compulsory military service. In preparation for that service, military physicians perform a thorough medical evaluation. Trained paramedics recorded every conscript's height and weight.
The study cohort was divided into five BMI percentile groups according to the U.S. Centers for Disease Control and Prevention's BMI percentiles for 17-year-olds, and further divided by sex: <5th percentile (underweight), 5th-49th percentile (low-normal), 50th-84th percentile (high normal), 85th-94th percentile (overweight) and ≥95th (obese). Low-normal was used as the reference group.
Adjustments were made for sex, birth year, age at examination, height, country of birth (Israeli or other), socioeconomic status, and education level.
In the fully adjusted results, those with severe ADHD were 32% more likely to be overweight and 84% more likely to be obese than their typically developing peers. Limiting results to Israeli-born conscripts made a no difference.
Male adolescents with mild ADHD were 24% more likely to be overweight, and 42% more likely to be obese. Females with mild ADHD are 33% more likely to be overweight, and 42% more likely to be obese. Again, the country of birth made no difference.
The authors concluded, that both severe and mild ADHD was associated with an increased risk for obesity in adolescents at the age of 17 years. The increasing recognition of the persistence of ADHD into adulthood suggests that this dual morbidity may have a significant impact on the long-term health of individuals with ADHD, thus early preventive measures should be taken.
Background:
Non-suicidal self-injury (NSSI) means intentionally hurting yourself without trying to end your life. Common examples include cutting, scratching, or burning yourself. This behavior is most common in teenagers, affecting 13-20% of adolescents. It’s also called self-harm or deliberate self-injury.
Young people who struggle with managing emotions, act impulsively, or have mental health conditions like depression are more likely to self-harm.
Because ADHD involves impulsivity and often occurs alongside emotional difficulties, researchers have suspected a link between ADHD and self-injury. However, previous studies have tended to be small, unrepresentative, and inconsistent, making it hard to draw clear conclusions.
The Study:
Researchers combined results from 14 different studies involving nearly 30,000 people to get a clearer picture. They looked at children, teenagers, and adults with ADHD from various settings—including hospitals, community programs, and general population studies.
To be included, studies had to confirm ADHD diagnosis through professional evaluation or validated testing methods.
Key findings
Conclusion:
The researchers concluded that roughly one in four people with ADHD have engaged in non-suicidal self-harm. The findings suggest that ADHD and self-harm share overlapping vulnerabilities.
Overall, this meta-analysis strengthens evidence that people with ADHD face a significantly elevated risk of non-suicidal self-injury, likely reflecting overlapping challenges with impulsivity, emotional regulation, and co-occurring mental health conditions. Importantly, this does not mean self-harm is inevitable in ADHD. It does, however, highlight the need for early screening, supportive environments, and targeted mental-health care to help reduce risk and support healthier coping strategies.
Background:
While ADHD is generally linked to negative childhood outcomes, individual variability exists. Researchers have found that factors like cognition, emotion, parenting, and social interactions can help some adversity-exposed children develop better than expected. This variability has driven extensive resilience research, which now views resilience not as a single trait, but as a combination of biological, psychological, social, and ecological processes supporting adaptation.
The Study:
This meta-analysis sought to address several key research gaps. First, while many potential resilience factors have been identified, no previous meta-analysis has quantitatively synthesized evidence focused specifically on children with ADHD. Second, relatively little research has clarified how particular resilience factors relate to specific developmental outcomes. Third, there is currently no integrated conceptual model of resilience processes tailored to children and adolescents with ADHD.
To keep the analysis focused and clinically relevant, the authors examined psychosocial and ecological resilience factors only. Biological factors (such as genetics or cardiovascular health) and non-modifiable demographic characteristics (such as age and sex) were excluded, as they do not readily inform interventions. The analysis also focused strictly on outcomes for children and adolescents with ADHD, excluding adult outcomes and those reported for parents or teachers. Only studies based on clinical ADHD diagnoses were included.
In total, 28 studies involving more than 11,600 participants met the inclusion criteria. Fifteen studies were rated as high quality and 13 as fair quality; none were rated low quality. However, the evidence base was relatively thin for many analyses. Of the 50 components examined, only one included five studies, six included four studies, ten included three studies, and most (33) were based on just two studies. While some components involved large samples, most did not, meaning the findings should be viewed as suggestive rather than definitive.
Results:
Unsurprisingly, academic skills and cognitive functioning – specifically including working memory and intelligence – were strongly associated with better educational outcomes for children and adolescents with ADHD. In contrast, social skills and proactive attitudes or behaviors showed no significant link to educational attainment.
Well-being outcomes showed a different pattern. Proactive attitudes and behaviors, cognitive functioning, and parental resources were associated with small-to-moderate improvements in well-being. Emotional regulation and positive parenting or attachment, however, were not significantly related to well-being in this analysis.
For relationship outcomes, peer relationships – especially close friendships – stood out as particularly important, showing strong associations with better relational functioning. Social skills and positive parenting or attachment were linked to moderate improvements, although positive parenting alone had no significant effect. This suggests that the observed benefit likely stemmed from parental warmth and secure parent–child attachment rather than parenting practices in isolation. Parental resources (such as parental social support) and school-based support (including student–teacher relationships) showed no significant association with relationship outcomes.
The study also examined behavioral symptoms. Externalizing symptoms refer to outward-directed behaviors that affect others or the environment, such as aggression, defiance, impulsivity, hyperactivity, and rule-breaking. Peer relationships were linked to a modest reduction in these behaviors, while positive relationships with adults were associated with a strong reduction. In contrast, disciplinary parenting – particularly harsh punishment – was strongly associated with increased externalizing symptoms.
Internalizing symptoms involve inward-directed distress, such as anxiety, depression, withdrawal, excessive worry, and unexplained physical complaints. Here again, positive relationships with adults were important, showing a moderate association with fewer internalizing symptoms. Emotional regulation was also linked to small-to-moderate improvements.
Conclusion:
Overall, the findings highlight that resilience factors tend to be closely tied to specific outcomes rather than broadly protective across domains. For example, emotional regulation was associated with lower levels of both internalizing and externalizing symptoms but showed no significant link to well-being, educational achievement, or relationship quality. This suggests that emotional regulation may play a particularly important role in protecting mental health in children with ADHD, rather than driving broader developmental gains – consistent with evidence that emotional dysregulation is a core difficulty in ADHD.
Similarly, academic skills, social competence, and prosocial behaviors were linked mainly to their most closely related outcomes. Cognitive functioning was associated with both educational and well-being outcomes, but its impact was much stronger in education and more modest for well-being. Together, these context-specific patterns underscore the importance of designing interventions that target particular resilience factors with strategies tailored to specific developmental goals, rather than assuming that any single factor will promote resilience across all areas of life.
Key takeaway: resilience is individual and resilience isn’t one trait; different types of support help different individuals, in different areas.
Background:
Traditional measures of obesity, like body mass index (BMI) and waist circumference, have been linked to ADHD risk — but they aren’t great at capturing where fat is actually stored in the body. A newer index called relative fat mass (RFM), which combines height and waist circumference, does a better job of estimating overall body fat and predicting metabolic risks like heart disease and metabolic syndrome. Because those conditions share some underlying biological mechanisms with ADHD, researchers wondered whether RFM might also help explain the relationship between obesity and ADHD — particularly in children.
That question is complicated by the fact that ADHD doesn't look the same in boys and girls. Boys tend to display more hyperactive and impulsive behavior, making their ADHD easier to spot. Girls more often show inattention, which is quieter and frequently goes undiagnosed.
The Study:
A new study set out to test whether RFM is associated with ADHD in children, and whether that association differs between sexes. Using data from the National Health and Nutrition Examination Survey (NHANES) collected between 1999 and 2004, the researchers narrowed a large initial pool of over 31,000 participants down to 5,089 children and adolescents aged 6 to 14 who had complete data on height, waist circumference, ADHD screening, and other relevant variables.
After adjusting for age, race/ethnicity, Poverty-Income Ratio, maternal age at delivery, maternal smoking during pregnancy, health insurance coverage, and birth weight, the results revealed a striking split along sex lines.
In boys, higher RFM was associated with lower odds of ADHD. Compared to boys in the lowest fat-mass quartile, those in the second quartile had about 10% lower odds of ADHD, rising to over 30% lower in the third quartile and nearly 40% lower in the highest. In girls, the pattern reversed entirely. While girls in the second quartile showed similar odds to those with the lowest RFM, girls in the third and fourth quartiles had 60% to 70% greater odds of ADHD.
Conclusion & Why This Matters:
In recent years, the relationship between obesity and ADHD has become an increasingly important focus in pediatric neurodevelopmental research. Studies have reported higher rates of ADHD symptoms among children and adolescents with obesity compared with their non-obese peers, and difficulties with peer relationships have also been linked to increased obesity risk (Sönmez et al., 2019). From a neurobiological standpoint, both conditions may involve shared underlying mechanisms, particularly dysfunction in dopaminergic pathways.
The authors concluded that higher body fat levels appear to lower ADHD risk in boys while raising it in girls. This finding highlights why sex-specific analysis matters in ADHD research. The underlying biological reasons for this divergence, however, remain an open question and open the door for future research.
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