March 22, 2021
A relatively new area of ADHD research has been examining the association between ADHD and eating disorders (i.e., anorexia nervosa, bulimia nervosa, and binge-eating disorder). Nazar and colleagues conducted a systematic review and meta-analysis of extant studies.
They found only twelve studies that assessed the presence of eating disorders among people with ADHD and five that examined the prevalence of ADHD among patients with eating disorders. Although there were few studies, the total number of people studied was large, with 4,013 ADHD cases and 29,404 controls for the first set of studies and 1,044 eating disorder cases and 11,292 controls for the second set of studies. The meta-analyses of these data found that ADHD people had a 3.8-fold increased risk for an eating disorder compared with non-ADHD controls. The level of risk was similar for each of the eating disorders. Consistent with this, their second meta-analysis found that people with eating disorders had a 2.6-fold increased risk for ADHD compared with controls who did not have an eating disorder. The risk for ADHD was highest for those with binge-eating disorder (5.8-fold increased risk compared with controls).
This bidirectional association between ADHD and eating disorders provides converging evidence that this association is real and, given its magnitude, clinically significant. The results were similar for males and females and pediatric and adult populations.
We cannot tell from these data why ADHD is associated with eating disorders. Nazar et al. note that other work implicates both impulsivity and inattention in promoting bulimic symptoms, whereas inattention and hyperactivity are associated with craving. The association may also be due to the neurocognitive deficits of ADHD, which could lead to a distorted sense of self-awareness and body image.
Given that ADHD is also associated with obesity, some obese ADHD patients may have an underlying eating disorder, such as binge-eating, which has been associated with obesity in prospective studies. Also, lisdexamfetamine is FDA-approved for treating both binge eating and ADHD, which suggests the possibility that the two conditions share an underlying etiology involving the dopamine system. We do not know if treating ADHD would reduce the risk for eating disorders, as that hypothesis has not yet been tested. But such an effect would seem likely if ADHD behaviors mediate the association between the two disorders.
Nazar, B. P., Bernardes, C., Peachey, G., Sergeant, J., Mattos, P. & Treasure, J. (2016). The risk of eating disorders comorbid with attention-deficit/hyperactivity disorder: A systematic review and meta-analysis. Int J Eat Disord 49,1045-1057.
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This New York Times article, “5 Takeaways from New Research about ADHD”, earns a poor grade for accuracy. Let’s break down their (often misleading and frequently inaccurate) claims about ADHD.
The Claim: A.D.H.D. is hard to define/ No ADHD Biomarkers exist
The Reality: The claim that ADHD is hard to define “because scientists haven’t found a single biological marker” is misleading at best. While it is true that no biomarker exists, decades of rigorous research using structured clinical interviews and standardized rating scales show that ADHD is reliably diagnosed. Decades of validation research consistently show that ADHD is indeed a biologically-based disorder. One does not need a biomarker to draw that conclusion and recent research about ADHD has not changed that conclusion.
Additionally, research has in fact confirmed that genetics do play a role in the development of ADHD and several genes associated with ADHD have been identified.
The Claim: The efficacy of medication wanes over time
The Reality: The article’s statement that medications like Adderall or Ritalin only provide short-term benefits that fade over time is wrong. It relies almost entirely on one study—the Multimodal Treatment Study of ADHD (MTA). In the MTA study, the relative advantage of medication over behavioral treatments diminished after 36 months. This was largely because many patients who had not initially been given medication stopped taking it and many who had only been treated with behavior therapy suddenly began taking medication. The MTA shows that patients frequently switched treatments. It does not overturn other data documenting that these medications are highly effective. Moreover, many longitudinal studies clearly demonstrate sustained benefits of ADHD medications in reducing core symptoms, psychiatric comorbidity, substance abuse, and serious negative outcomes, including accidents, and school dropout rates. A study of nearly 150,000 people with ADHD in Sweden concluded “Among individuals diagnosed with ADHD, medication initiation was associated with significantly lower all-cause mortality, particularly for death due to unnatural causes”. The NY Times’ claim that medications lose their beneficial effects over time ignores compelling evidence to the contrary.
The Claim: Medications don’t help children with ADHD learn
The Reality: ADHD medications are proven to reliably improve attention, increase time spent on tasks, and reduce disruptive behavior, all critical factors directly linked to better academic performance.The article’s assertion that ADHD medications improve only classroom behavior and do not actually help students learn also oversimplifies and misunderstands the research evidence. While medication alone might not boost IQ or cognitive ability in a direct sense, extensive research confirms significant objective improvements in academic productivity and educational success—contrary to the claim made in the article that the medication’s effect is merely emotional or perceptual, rather than genuinely educational.
For example, a study of students with ADHD who were using medication intermittingly concluded “Individuals with ADHD had higher scores on the higher education entrance tests during periods they were taking ADHD medication vs non-medicated periods. These findings suggest that ADHD medications may help ameliorate educationally relevant outcomes in individuals with ADHD.”
The Claim: Changing a child’s environment can change his or her symptoms.
The Reality: The Times article asserts that ADHD symptoms are influenced by environmental fluctuations and thus might not have their roots in neurobiology. We have known for many years that the symptoms of ADHD fluctuate with environmental demands. The interpretation of this given by the NY Times is misleading because it confuses symptom variability with underlying causes. Many disorders with well-established biological origins are sensitive to environmental factors, yet their biology remains undisputed.
For example, hypertension is unquestionably a biologically based condition involving genetic and physiological factors. However, it is also well-known that environmental stressors, dietary
habits, and lifestyle factors can significantly worsen or improve hypertension. Similarly, asthma is biologically rooted in inflammation and airway hyper-reactivity, but environmental triggers such as allergens, pollution, or even emotional stress clearly impact symptom severity. Just as these environmental influences on hypertension or asthma do not negate their biological basis, the responsiveness of ADHD symptoms to environmental fluctuations (e.g., improvements in classroom structure, supportive home life) does not imply that ADHD lacks neurobiological roots. Rather, it underscores that ADHD, like many medical conditions, emerges from the interplay between underlying biological vulnerabilities and environmental influences.
Claim: There is no clear dividing line between those who have A.D.H.D. and those who don’t.
The Reality: This is absolutely and resoundingly false. The article’s suggestion that ADHD diagnosis is arbitrary because ADHD symptoms exist on a continuum rather than as a clear-cut, binary condition is misleading. Although it is true that ADHD symptoms—like inattention, hyperactivity, and impulsivity—do vary continuously across the population, the existence of this continuum does not make the diagnosis arbitrary or invalidate the disorder’s biological basis. Many well-established medical conditions show the same pattern. For instance, hypertension (high blood pressure) and hypercholesterolemia (high cholesterol) both involve measures that are continuously distributed. Blood pressure and cholesterol levels exist along a continuum, yet clear diagnostic thresholds have been carefully established through decades of clinical research. Their continuous distribution does not lead clinicians to question whether these conditions have biological origins or whether diagnosing an individual with hypertension or hypercholesterolemia is arbitrary. Rather, it underscores that clinical decisions and diagnostic thresholds are established using evidence about what levels lead to meaningful impairment or increased risk of negative health outcomes. Similarly, the diagnosis of ADHD has been meticulously defined and refined over many decades using extensive empirical research, structured clinical interviews, and validated rating scales. The diagnostic criteria developed by experts carefully delineate the point at which symptoms become severe enough to cause significant impairment in an individual’s daily functioning. Far from being arbitrary, these thresholds reflect robust scientific evidence that individuals meeting these criteria face increased risks for the serious impairments in life including accidents, suicide and premature death.
The existence of milder forms of ADHD does not undermine the validity of the diagnosis; rather, it emphasizes the clinical reality that people experience varying degrees of symptom severity.
Moreover, acknowledging variability in severity has always been a core principle in medicine. Clinicians routinely adjust treatments to meet individual patient needs. Not everyone diagnosed with hypertension receives identical medication regimens, nor does everyone with elevated cholesterol get prescribed the same intervention. Similarly, people with ADHD receive personalized treatment plans tailored to the severity of their symptoms, their specific impairments, and their individual circumstances. This personalization is not evidence of arbitrariness; it is precisely how evidence-based medicine is practiced. In sum, the continuous nature of ADHD symptoms is fully compatible with a biologically-based diagnosis that has substantial evidence for validity, and acknowledging symptom variability does not render diagnosis arbitrary or diminish its clinical importance.
In sum, readers seeking a balanced, evidence-based understanding of ADHD deserve clearer, more careful reporting. By overstating diagnostic uncertainty, selectively interpreting research about medication efficacy, and inaccurately portraying the educational benefits of medication, this article presents an overly simplistic, misleading picture of ADHD.
Recent research suggests that inflammation may play a role in ADHD. Inflammation, marked by elevated proteins and cytokines, affects brain development and structure. Evidence suggests it plays a role in the development of ADHD, making the study of inflammatory markers crucial.
The platelet-to-lymphocyte ratio (PLR) is a cost-effective test for predicting outcomes of chronic inflammation and neuroimmune diseases. Studies show PLR may be an important inflammatory marker in the pathophysiology of ADHD in children.
The Study:
A Chinese study team used the National Health and Nutrition Examination Survey (NHANES) database maintained by the National Center for Health Statistics of the United States to investigate the association between PLR and ADHD in children aged 6–14.
The team identified ADHD through prescriptions of ADHD medications.
After exclusions for missing information, the study encompassed 1,455 children.
The authors adjusted for the following potential confounders: sex, age, race, poverty-to-income ratio, maternal age at childbirth, smoking during pregnancy, asthma, health insurance status, dietary inflammatory index, monocyte count, segmented neutrophil count, eosinophil count, and basophil count.
They also split the PLR results into quartiles, with the first quartile having the lowest readings.
Prescriptions of ADHD medications were twice as frequent among children in the second quartile as they were among children in the first quartile. They were four times as frequent among children in the third quartile than among children in the first quartile.
Conclusion:
The team concluded, “These findings further support the potential role of inflammation in the onset and development of ADHD, providing preliminary evidence for PLR as a potential biomarker for ADHD and suggesting its possible use in identifying high-risk populations. However, considering the limitations of this study, future research should be designed as larger-scale, prospective, multi-center randomized controlled trials to validate these findings and further explore the relationship between inflammatory mechanisms and ADHD.”
In other words, this study suggests that while high PLR values may serve as a potential biomarker for ADHD, particularly in specific high-risk groups, further research is needed to confirm these findings and fully understand the role of inflammation in ADHD development. Larger, more robust studies will be crucial to validating PLR as a reliable tool for identifying at-risk populations.
ADHD is the most prevalent neurodevelopmental disorder. Nearly 1% of pregnant women in the Nordic countries and more than 1% in the United States are prescribed ADHD medications, ranking these among the most commonly used medications during pregnancy. However, the safety of exposing a fetus to ADHD medications is still uncertain, prompting many expectant mothers to stop using them out of fear for their unborn child’s well-being.
The Study:
A European research team conducted a comprehensive nationwide study on the safety of ADHD medications during pregnancy using populations from Sweden and Denmark. The Swedish population was studied first, followed by inclusion of a separate study of the Danish population. Results were then combined through meta-analysis. Nordic countries, with their single-payer national health insurance systems and national population registers, facilitate the tracking of residents’ health from birth to death, thus providing robust data for such studies.
The team accounted for various potential confounders, including maternal age, year of delivery, whether the mother was a first-time parent, self-reported smoking during pregnancy, and any psychiatric history. They also considered psychiatric inpatient or outpatient treatment received within two years before pregnancy, as well as the dispensing of other psychotropic medications during pregnancy, including antidepressants, antipsychotics, antiseizure medications, and anti-anxiety medications. Additionally, they examined the highest level of maternal education and civil status at delivery (married or cohabiting compared to single, divorced, or widowed).
Out of 861,650 Swedish children, 2,257 were exposed to ADHD medications during pregnancy. Another 3,917 were born to mothers who discontinued ADHD medications before pregnancy.
Children exposed to ADHD medications had lower rates of ADHD, autism spectrum disorder, and overall neurodevelopmental disorders; however, none of these differences were significant.
Limiting the analysis to siblings to control for family environmental influences and genetics likewise found no significant differences.
A meta-analysis combining the Swedish results with a separately conducted nationwide population study in neighboring Denmark similarly found no significant differences between children exposed to ADHD medications during pregnancy and children born to mothers who discontinued ADHD medications before pregnancy.
Conclusion:
The team concluded, “Overall, our study provides reassuring evidence that continuing ADHD medication during pregnancy does not increase the risk of long-term NDDs [neurodevelopmental disorders] in offspring."
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