June 24, 2021

Associations between ADHD and autoimmune diseases

A Norwegian team based at the University of Bergen recently performed a population study using the country's detailed national health registries. With records from more than two and a half million Norwegians, the team examined what, if any, associations could be found between ADHD and nine autoimmune diseases: ankylosing spondylitis, Crohn's disease, iridocyclitis, multiple sclerosis, psoriasis, rheumatoid arthritis, systemic lupus erythematosus, type 1 diabetes, and ulcerative colitis.

After adjusting for age and maternal education, the team found no association between ADHD and five of the nine autoimmune disorders: type 1 diabetes, rheumatoid arthritis, iridocyclitis, systemic lupus erythematosus, and multiple sclerosis. In the case of ankylosing spondylitis, it found no association with males with ADHD, but a negative association with females. Females with ADHD were less likely to have ankylosing spondylitis. The adjusted odds ratio (AOR) was 0.56 (95% CI 0.32-0.96).

Positive associations were found for only three autoimmune diseases. The strongest was for psoriasis, with adjusted odds ratios of 1.6(95% CI 1.5-1.7) for females and 1.3 (95% CI 1.2-1.4) for males. When further adjusted for education, smoking, and body mass index (BMI), however, the adjusted odds ratio for females with ADHD dropped to 1.3 (95% CI 1.0-1.6).

The second-strongest association was with Crohn's disease. But here it was only among women. The odds ratio, in this case, was 1.4 (95% CI 1.2-1.8). Males with ADHD were less likely to have Crohn's disease, with an odds ratio of 0.71 (95% CI 0.54-0.92).

Finally, females with ADHD were slightly more likely to have ulcerative colitis, with a barely significant odds ratio of 1.3 (95% CI 1.1-1.5), while no such association was found for males with ADHD, whose odds ratio was a statistically non-significant 0.9.

Given the large sample size of over two and a half million, this is no underpowered study. It found no association between ADHD and the generic category of autoimmune disorders. Furthermore, it is a stretch to argue that there are any clear and clinically meaningful links between ADHD and any of the specific disorders that were analyzed in this study. The small and often opposite effect sizes may simply reflect limitations with the data (presumed autoimmune disorders were identified based on drugs prescribed), or other unidentified confounding factors.

Tor‐Arne Hegvik, Johanne TelnesInstanes, Jan Haavik, Kari Klungsøyr, Anders Engeland, “Associations between attention‐deficit/hyperactivity disorder and autoimmune diseases are modified by sex: a population‐based cross‐sectional study,” European Child & Adolescent Psychiatry, vol. 27 (2018),663-675.

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Inflammation and Childhood ADHD: Platelet-to-Lymphocyte Ratios

Dose-response Association Found Between Platelet-to-Lymphocyte Ratio (PLR) and Childhood 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.

April 15, 2025

Meta-analysis of Two Nationwide Population Studies Finds No Harm to Offspring from Taking ADHD Medications During Pregnancy

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." 

From Meds to Mindfulness: What Actually Works for Adult ADHD?

A new large-scale study has shed light on which treatments for attention-deficit/hyperactivity disorder (ADHD) in adults are most effective and best tolerated. 

Researchers analyzed 113 randomized controlled trials involving nearly 15,000 adults diagnosed with ADHD. These studies included medications (like stimulants and atomoxetine), psychological therapies (such as cognitive behavioral therapy), and newer approaches like neurostimulation.

The Findings

Stimulant medications (lisdexamfetamine and methylphenidate) as well as selective norepinephrine reuptake inhibitors (SNRI) (atomoxetine) were the only treatments that consistently reduced core ADHD symptoms—both from the perspective of patients and clinicians. It may be worth noting that atomoxetine, while effective, was less well tolerated, with more people dropping out due to side effects.

Psychological therapies such as CBT, mindfulness, and psychoeducation showed some benefits, but mainly according to clinician ratings—not necessarily from the patients themselves. Neurostimulation techniques like transcranial direct current stimulation also showed some improvements, but only in limited contexts and with small sample sizes. Interestingly, none of the treatments—medication or otherwise—made a clear impact on long-term quality of life or emotional regulation. 

Conclusion 

So, what does this mean for people navigating ADHD in adulthood? Stimulant medications remain the most effective treatment for managing ADHD symptoms day-to-day but nonstimulant medication are not far behind, which is good given the problems we’ve had with stimulant shortages. This study also supports structured psychotherapy as a viable treatment option, especially when used in conjunction with medication. 

The study emphasizes the importance of ongoing, long-term research and the need for treatment plans that are tailored to the individual ADHD patient– Managing adult ADHD effectively calls for flexible, patient-centered care.

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