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Vitamins play important roles in metabolism, immune regulation, and neurodevelopment. Recent studies show that deficiencies in vitamins like D, B6, B12, and folate are common in people with ADHD and ASD (autism spectrum disorder), and are associated with behavioral, cognitive, and brain development issues. 

The Study:

A study team based in China has just performed a systematic search of the peer-reviewed medical literature to perform meta-analyses of clinical trials exploring vitamin interventions in the treatment of ADHD and ASD.  

ADHD trials included participants with an official diagnosis. The primary intervention was vitamin supplements, while other treatments, including medications, remained unchanged or were excluded during the study period. ADHD outcomes included measurable changes in ADHD symptoms using validated rating scales and executive function measures. 

Eligible studies included standard or sham control groups, crossover, parallel, or other clinical trial designs. In crossover studies, only first-phase data were analyzed to prevent carryover effects. 

Ten trials with 852 participants met the standards, but meta-analysis showed no significant results. The outcomes varied widely, suggesting a need to distinguish among vitamins. 

Results:

Of the five trials involving 347 participants that specifically evaluated vitamin D supplementation, results indicated a large effect size improvement in ADHD symptoms and executive function measures. The other five studies did not show any observable improvement. 

Key limitations include: 

• Vitamin D supplementation studies were not separately assessed. 

• High heterogeneity persisted in study outcomes, likely due to varying study designs. 

• Participant numbers were relatively small. 

The team concluded, “This meta-analysis supports the use of vitamin supplementation as a promising adjunctive treatment for ASD and ADHD. Vitamin B showed greater benefits in improving symptoms of ASD, while vitamin D was more effective in managing ADHD-related behaviors. These findings suggest that specific vitamins may target disorder-specific symptoms. Despite limitations such as the lack of trials on other vitamins and limited understanding of underlying mechanisms, vitamin therapy remains a low-cost, accessible option.” 

An important limitation of this work is that the positive results for vitamin D were due to two studies from Iran.  So far, no positive study has emerged from a non-Iranian study.

Interpretation: 

The vitamin D findings are intriguing and could be important if replicated outside of Iran. Since supplementation is already widely recommended to those with limited sunlight exposure, clinicians may want to consider monitoring their patients’ vitamin D intake, especially in the winter months. It should be noted, however, that due to the limitations of this study, the results are by no means conclusive, and vitamin D should not be taken as a stand-alone treatment for ADHD. 

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Claims-based real-world data can reveal population-level trends in health among people with neurodevelopmental disorders. This new study examined the prevalence, demographics, and chronic comorbidities of adults and of children and adolescents with ADHD in a large national health plan. It also compared healthcare use and costs between those with and without ADHD. 

A research team in the United States conducted an observational cohort study using claims data from more than 1.9 million adults and nearly 500,000 children and adolescents, comparing individuals diagnosed with ADHD to those without the diagnosis. 

ADHD was diagnosed in 4% of adults and in 5% of children and adolescents. 

Comorbidities By The Numbers: 

Disruptive childhood disorders are behavioral problems marked by ongoing defiance, uncooperativeness, and aggression that affect a child's daily life and relationships. The main types, oppositional defiant disorder (ODD) and conduct disorder (CD), involve persistent anger and argumentativeness in ODD, and more severe actions like aggression, cruelty, and criminal behavior in CD. Without treatment, these common childhood disorders can continue into adulthood and raise the risks of substance use, violence, incarceration, and early death. 

Disruptive childhood disorders were twenty times more frequent among children and adolescents with ADHD than among those without ADHD diagnosis, and fifteen times more frequent among adults with ADHD. 

Bipolar disorder was twelve times more common among children and adolescents with ADHD than those without ADHD, and seven times more common among adults with ADHD. 

Schizophrenia was eleven times more prevalent among children and adolescents with ADHD than those without ADHD, and three-and-a-half times more common among adults with ADHD. 

Anxiety was nine times more frequent among children and adolescents with ADHD than among those without ADHD diagnosis, and more than five times more frequent among adults with ADHD. 

Depression was eight times more common among children and adolescents with ADHD than those without ADHD, and more than five times more common among adults with ADHD. 

Suicidal ideation was eight times more prevalent, and suicide attempt seven times more prevalent, among children and adolescents with ADHD than those without ADHD. Both suicidal ideation and suicide attempt were five times more common among adults with ADHD. 

Gender dysphoria was almost six times more frequent among children and adolescents with ADHD than among those without ADHD diagnosis, and five times more frequent among adults with ADHD.  

Eating disorders were over four times more common among children and adolescents with ADHD than those without ADHD, and five times more common among adults with ADHD. 

Substance-related disorders were over six times more prevalent, and alcohol use disorder was six times more prevalent among children and adolescents with ADHD than those without ADHD, and four and three times more prevalent among adults with ADHD. 

Increased Costs of Medical Care:

These comorbidities and ADHD led to higher medical costs. Children and adolescents with ADHD spent $610 more annually on healthcare than those without, while adults with ADHD had $1,684 higher average yearly expenditures than non-ADHD adults. 

The Take-Away:

This large claims-based analysis of a national commercial insurer found ADHD diagnoses in roughly 4% of adults and 5% of children. It documented substantially higher rates of co-occurring behavioral-health conditions and markedly greater healthcare utilization and expenditures among those with ADHD. The authors report increased odds for several co-occurring diagnoses, as well as higher per-member-per-month (PMPM) spending and per-thousand-per-month (PTPM) utilization, largely driven by greater use of behavioral health services. 

Importantly, these results come from cross-sectional, claims data within a commercially insured population: they describe associations, not causal relationships, and may not generalize to uninsured, publicly insured, or otherwise different populations. These findings, therefore, warrant cautious interpretation and highlight the need for longitudinal and more representative studies to clarify drivers of the increased burden and to inform care and policy.

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Background: 

Since the first in vitro fertilization (IVF) in 1978, assisted reproductive technology (ART) has led to over 10 million births worldwide.  

There are four types of embryo transfers, depending on whether they are fresh or frozen, and on their developmental stage. 

Fresh cleavage stage embryos are transferred on day 2 or 3 following fertilization and typically contain four to eight relatively large, undifferentiated cells. Fresh blastocyst embryos are transferred on day 5 or 6 after fertilization. At this point, they have developed over a hundred cells and have differentiated into two types: the inner cell mass, which develops into the fetus, and the outer cell layer, which forms the placenta. 

Globally, more children are now born through assisted reproductive technology using frozen-thawed embryo transfer than fresh embryo transfer.  

Research suggests that ART-conceived offspring may face increased risks of cardiovascular, musculoskeletal, chromosomal, urogenital diseases, and cancers. Might they also be at increased risk for ADHD? 

Study:

Taiwan’s single-payer health insurance covers over 99% of people and records all their healthcare activity. Since 1998, it has kept an ART database for all couples registered for IVF treatment. 

A Taiwanese research team reviewed all records for the five-year period from 2013 through 2017, ultimately analyzing 3,125 live singleton births from fresh cleavage stages, 1,332 from fresh blastocysts, 1,465 from frozen cleavage stages, and 4,708 from frozen blastocysts, alongside 878,643 naturally conceived singleton births. 

The team controlled for the following potential confounders: pregnancy-induced hypertension, chronic hypertension, diabetes mellitus, gestational diabetes mellitus, unhealthy lifestyle, placenta previa, placenta abruption, preterm premature rupture of membrane, and postpartum hemorrhage. 

Results:

With these adjustments, cleavage stage embryo transfers, whether fresh or frozen, were associated with a seven-fold higher rate of ADHD diagnosis in offspring than natural conception. 

Frozen blastocyst embryo transfers were likewise linked to a seven-fold increase in ADHD diagnoses in offspring compared to natural conception. Notably, fresh blastocyst transfers showed a 19-fold increase, likely due to the smaller number of cases in this category. 

The team concluded, “Compared to natural conception, ART is associated with higher risks, particularly for preterm birth, ADHD, and developmental delay.” 

Conclusion: 

This large national cohort suggests that ART-conceived singletons face higher rates of several adverse outcomes, including preterm birth, ADHD, and developmental delay. Clinicians and prospective parents should therefore weigh these potential associations when counseling and planning care, prioritize optimized ART protocols and perinatal management, and ensure early developmental surveillance for ART-conceived children so concerns can be identified and addressed promptly.

It is important to note that the findings also point to the likely contribution of underlying parental infertility in these developmental outcomes. Future research should aim to disentangle parental- versus procedure-related risks to clarify absolute risk magnitudes. As always, associations of this time should not be interpreted as causal due to the inability of observational studies to rule out all possible confounding factors.

Attention-Deficit/Hyperactivity Disorder (ADHD) is one of the most common neurodevelopmental conditions, yet many young people, especially girls, receive a diagnosis late or not at all. This matters, because a delayed diagnosis often means missed opportunities for support, treatment, and improved long-term outcomes. A recent study by Barclay and colleagues (2024) sheds new light on why ADHD recognition is inconsistent, and what we can do about it.

The Study:

Researchers analyzed data from nearly 10,000 children in the UK Millennium Cohort Study. They compared children whose ADHD was recognized early (ages 5–7), later (ages 11–14), or not recognized at all, despite evidence of symptoms. The team also looked at differences between boys and girls to better understand why diagnosis patterns vary by sex.

Key Findings:

1. Severity Drives Earlier Recognition
   Children who were diagnosed at a younger age often had more visible difficulties: emotional outbursts, peer conflict, conduct issues, and lower cognitive scores. In other words, the “louder” and more disruptive the symptoms, the more likely ADHD was flagged early.
   
   
2. “Quieter” ADHD May Be Overlooked
   Children with stronger prosocial skills or higher cognitive ability were less likely to be recognized, even if they had clear ADHD symptoms. These children may be able to “mask” their difficulties, or adults may misinterpret their struggles as personality quirks rather than signs of ADHD.
   
   
3. Emotional Dysregulation Matters
   Emotional dysregulation—big swings in mood, difficulty calming down, intense frustration—was strongly linked to recognized ADHD in boys, but not in girls. This suggests that clinicians may pay closer attention to these behaviors in boys, while overlooking them in girls.
   
   
4. Co-occurring Conditions Can Influence Diagnosis
   Children with autism were more likely to have their ADHD identified. On the flip side, those who engaged in more physical activity were slightly less likely to be recognized, though the reasons for this are not yet clear.
   
   

What This Means for Clinicians:

The study highlights the importance of looking beyond the “classic” hyperactive child stereotype when considering ADHD. Clinicians should:

• Pay attention to symptoms of emotional dysregulation, even if they are not part of standard diagnostic checklists.
  
  
• Consider ADHD in children with good grades or strong social skills if other symptoms are present.
  
  
• Be mindful of gender differences, since girls may be more likely to internalize symptoms or present with inattentiveness rather than hyperactivity.
  
  

What This Means for Parents and Patients:

If you’re a parent, it’s important to trust your observations. If your child struggles with focus, organization, or emotional regulation—even if they are doing well academically or socially—these could still be signs of ADHD. Advocating for an evaluation can make a big difference.

Moving Forward

This study makes clear that ADHD is not one-size-fits-all. Recognition often depends on how symptoms show up, how disruptive they appear, and even the child’s gender. By broadening our awareness and refining our screening practices, we can ensure that fewer children slip through the cracks and more receive the support they need early in life.

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Parents and teachers often ask: Does ADHD medication actually improve grades and school performance? The answer is: yes, but with important limitations. Medications are very effective at reducing inattention, hyperactivity, and impulsivity but their impact on long-term academic outcomes like grades and test scores is not as consistent.

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In the Classroom

The medications for ADHD consistently: Improve attention, reduce classroom disruptions, increase time spent on-task and help children complete more schoolwork and homework. Medication can help children with ADHD access learning by improving the conditions for paying attention and persisting with work.

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Does Medication Improve Test Scores and Grades?

This is where the picture gets more complicated.  Medications have  stronger effect on how much work is completed but a weaker effect on accuracy. Many studies show that children on medication attempt more problems in reading, math, and spelling, but the number of correct answers doesn’t always improve as much. Some studies find small but significant improvements in national exam scores and higher education entrance tests during periods when children with ADHD are medicated.

Grades improve, as well, but modestly. Large registry studies in Sweden show that students who consistently take medication earn higher grades than those who don’t. However, these gains usually do not close the achievement gap with peers who do not have ADHD.

Keep in mind that small improvements for a group as a whole mean that some children are benefiting greatly from medication and others not at all.  We have no way of predicting which children will improve and which do not. 

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Medication Alone Isn’t Enough

Academic success depends on more than just reducing inattention, hyperactivity and impulsivity. Skills like organization, planning, studying, and managing long-term projects are also critical.  Medication cannot teach these skills.

So, in addition to medication, the patient's treatment program should include educational support (tutoring, structured study skills programs), behavioral interventions (parent training, classroom management strategies), and accommodations at school (extra time, reduced distractions, organizational aids) Parents should discuss with their prescriber which of these methods would be appropriate.

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Conclusions 

ADHD medication is a powerful tool for reducing symptoms and supporting learning. It improves test scores and grades for some children, especially when taken consistently. But it is not a magic bullet for academic success. The best results come when medication is combined with educational and behavioral supports that help children build the skills they need to thrive in school and beyond.

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ADHD is usually framed as a dopamine-and-norepinephrine condition, but recent studies have revealed that serotonin may also play a significant role. To delve deeper into this, we conducted a systematic literature review of studies looking at serotonin, its receptors, and the serotonin transporter (SERT) in relation to ADHD. The result: serotonin appears to be an important piece of the puzzle, but the overall picture is quite complex.

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‍An ADHD & Serotonin Literature Review:

‍The authors searched the literature without time limits and screened thousands of records to end up with 95 relevant publications. Those included animal/basic-science work, neuroimaging, pharmacodynamics, a couple of large genetic/transcriptomic studies (GWAS and a cortico-striatal TWAS), and a few clinical reports. Each paper was graded for quality: 17 high, 59 medium, and 19 low.

The Results:

• Most studies support a serotonergic role. About 81% (77/95) of the papers reported altered serotonin production, binding, transport, or degradation linked to ADHD or ADHD-like behaviors.
  
  
• Multiple lines of evidence: animal models frequently show that changing serotonin levels or receptor activity alters hyperactivity and impulsivity; human imaging and clinical studies provide supportive but smaller and sometimes mixed signals; genetic/transcriptomic work points to serotonin-related pathways among many implicated systems.
  
  
• Receptors and SERT matter: Multiple serotonin receptor subtypes (5-HT1A, 1B, 2A, 2C, 7) and SERT show associations with impulsivity, hyperactivity, attention, or brain activity patterns in ADHD models and some human studies.
  
  
• Mixed and conflicting data: Central measures (brain, CSF) more often show serotonin deficits, while peripheral measures (platelets, plasma) sometimes show higher serotonin — methodological differences likely explain some contradictions.
  
  
• Drugs used for ADHD can affect serotonin: Stimulants and non-stimulant drugs approved by FDA for treating ADHD (e.g., methylphenidate, atomoxetine, extended release viloxazine) or under investigation (centafafadine) have direct or indirect effects on serotonin systems, supporting the idea that monoamines interact rather than acting separately.  Because drugs that mainly affect serotonin are not useful for ADHD it seems likely that a pathway forward for ADHD drug development would be drugs that target multiple neurotransmitter systems.  A complex treatment for an etiologically complex disorder.
  
  

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The Role of Serotonin in ADHD: What's The Take-Away?

As the study points out, the idea that serotonin may play a role in the neurobiology of ADHD is not new, but this literature review “identified multiple individual strands of evidence gathered over several decades and brought them into a more coherent focus”. It concludes that serotonergic neurotransmission is implicated in ADHD.  This doesn’t mean variations in serotonin levels cause ADHD, but that serotonin may be a plausible target for future treatments and research.

ADHD is polygenic and multi-systemic. For now, clinicians and patients should view serotonin as part of a complex network that may contribute to ADHD symptoms.  More research is needed before making treatment decisions based on these findings. 

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Background:

A previous meta-analysis found that children born to mothers with diabetes had a 34% higher risk of developing ADHD compared to those born to non-diabetic mothers.  

However, previous studies suffered methodological limitations, such as small sample sizes, case-control or cross-sectional designs, and insufficient adjustment for key confounders such as maternal socio-economic status, mental health conditions, obesity, and substance use disorders.  

Moreover, many studies relied on self-reported maternal diabetes, and on non-clinical ADHD assessments, such as parental reports or screening tools, which are prone to bias and inaccuracies.  

Furthermore, the role of maternal antidiabetic medication use in relation to ADHD risk has rarely been examined. Antidiabetic medications are effective in controlling high blood sugar during pregnancy, but many can cross the placenta and the blood-brain barrier, raising concerns about potential effects on fetal brain development.  

Study:

To address these gaps, an Australian study team used a large cohort of linked health administrative data from New South Wales to investigate both the association between maternal diabetes and the risk of ADHD and the independent effect of prenatal exposure to antidiabetic medications. 

The study encompassed all mother-child pairs born from 2003 through 2005, with follow-up conducted through 2018 to monitor hospital admissions related to ADHD. That yielded a final cohort of almost 230,000 mother-child pairs. 

The team adjusted for potential confounders including maternal age, socioeconomic status, previous children, pregnancy-related hypertension, caesarean delivery, birth order and plurality, maternal anxiety, depression, schizophrenia, bipolar disorder, substance use (alcohol, tobacco, stimulants, opioids, cannabis), and child factors such as Apgar score, sex, prematurity, and low birth weight. 

Results:

For maternal diabetes overall, there was no significant association with offspring ADHD. That was also true when broken down into pre-existing maternal diabetes and gestational (pregnancy-induced) diabetes.  

In a subset of 11,668 mother-child pairs, including 3,210 involving exposure to antidiabetic medications, there was likewise no significant association with offspring ADHD. 

Conclusion:

The team concluded, “Our findings did not support the hypothesis that maternal diabetes increases the risk of ADHD in children. Additionally, maternal use of antidiabetic medication was not associated with ADHD.” 

This study highlights the importance of high-quality research. A previous meta-analysis linking ADHD and maternal diabetes did not appropriately adjust for confounders and cited many small studies that may have included biased self-report scales. This large, registry-based cohort study of nearly 230,000 mother–child pairs found no evidence that maternal diabetes—whether pre-existing or gestational—or prenatal exposure to antidiabetic medications was associated with subsequent offspring ADHD as measured by hospital-recorded ADHD outcomes. The study’s strengths include its population scale, prolonged follow-up, and extensive adjustment for maternal and perinatal confounders (including maternal mental health and substance-use disorders), which address many limitations of earlier, smaller studies that reported elevated risks.  

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Background: 

The COVID-19 pandemic brought environmental changes that may have influenced ADHD symptoms and contributed to higher diagnosis rates. School closures, the transition to remote learning, and restrictions on outdoor activities led to increased screen time and isolation, both of which can affect attention and behavioral regulation. Children and adolescents, who usually depend on social interactions and structured routines, experienced significant disruptions during this period.  

Method:

South Korea has a nationwide single-payer health insurance system that keeps detailed health records on virtually its entire population. To explore the impact of COVID-19 on ADHD, a Korean research team used a database established by the Korean government that tracked all patients with COVID-19 between 2020 and 2023, nationwide COVID vaccination records, and insurance claims. They included all participants aged 6 through 29 years old. 

The onset of ADHD was determined by diagnosis combined with the prescription of ADHD medication. 

Altogether, the study encompassed almost 1.2 million Koreans, including over 150,000 children (6-12), more than 220,000 adolescents (13-19), and almost 800,000 young adults (20-29). 

The team adjusted for age, sex, income, Charlson Comorbidity Index, and medical visits. The Charlson Comorbidity Index predicts the mortality for a patient who may have a range of 17 concurrent conditions, such as heart disease, AIDS, or cancer. 

Results:

With these adjustments, young adults known to be infected with COVID-19 were about 40% more likely to be subsequently diagnosed with ADHD than their counterparts with no record of such infection. 

Adolescents known to be infected with COVID-19 were about twice as likely to be subsequently diagnosed with ADHD than their counterparts with no record of such infection. 

Children known to be infected with COVID-19 were 2.4 times as likely to be subsequently diagnosed with ADHD than their counterparts with no record of such infection. 

All these results were highly significant, and point to much greater impact on the youngest persons infected. 

Interpretation: 

The team concluded, “our nationwide study revealed that the COVID-19 pandemic significantly influenced ADHD incidence (raising incidence between 2020 and 2023), with SARS-CoV-2 infection identified as a critical risk factor,” and “In particular, early intervention and neurological evaluations are needed for children, adolescents, and young adults with a history of SARS-CoV-2 infection.” 

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Background: 

Children with ADHD often experience deficits in cognitive processes called executive functions. One of the main executive functions is working memory, which is crucial for learning and problem-solving. Issues related to working memory can impact not just academic performance, but also self-esteem, social interactions, and future career prospects. Daily challenges can include completing homework, remembering tasks, and maintaining focus in class, further complicating the learning and social experiences of those with ADHD. 

Physical activity boosts blood flow to the brain. It also assists neural plasticity, meaning it enables networks of nerve cells to reorganize their connections and grow new connections. That helps improve physical skills and potentially academic performance. It is an engaging, easy-to-implement intervention that effectively and sustainably increases children’s participation, overcoming many limitations of other methods. 

Study: 

A Chinese study team set out to perform a systematic search of the published peer-reviewed medical literature to conduct a meta-analysis focusing specifically on the efficacy of physical activity for boosting working memory. 

The inclusion criteria were fourfold. Studies had to: 

• Provide data specific to children and adolescents 18 years old and under. 

• Rely on clinical diagnoses of ADHD. 

• Involve interventions consisting of physical activity or exercise, including but not limited to aerobic exercise, resistance training, and team sports. 

• Have a minimum duration of five weeks. 

• Be randomized controlled trials (RCTs) or controlled non-randomized experimental studies. 

Eleven studies with a combined total of 588 participants met the inclusion criteria. Five were rated high quality. None were rated low quality. 

Results:

Meta-analysis of these eleven studies yielded a medium effect size improvement in working memory. Variability in study outcomes was acceptable (low heterogeneity). There was no indication of publication bias. 

Combined cognitive and aerobic interventions were associated with more than double the effect size of simple aerobic interventions, reaching large effect size (4 studies, 233 participants). 

Subgroup analysis favored a happy medium, suggesting there are points beyond which more is not better:  

• Hour-long interventions were associated with the greatest improvements, with large effect size (3 studies, 180 participants).  

• Interventions carried out no more than twice a week reached large effect size (3 studies, 130 participants).  

• Total weekly intervention time of no more than 25 hours also reported a large effect size (4 studies, 144 participants).  

Take-Away:

Because this work focuses on working memory, not the symptoms of ADHD, one cannot conclude that physical activity could replace current therapies for ADHD.  It does, however, provide strong evidence that physical activity interventions can meaningfully improve working memory in children with ADHD. The most consistent benefits were seen with structured programs of moderate duration and frequency. As with previous studies, the results seem to suggest that interventions excessively long in duration may have diminishing results, highlighting the importance of optimizing session length, frequency, and total intervention time. Before recommending very specific exercises and durations, however, further study is still needed. Future research should refine protocols and explore mechanisms that maximize effectiveness.

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The Background: 

Randomized clinical trials have shown ADHD medications are effective in reducing core ADHD symptoms. Moreover, large observational studies indicate that these medications are associated with lower risks of real-world outcomes, including injuries, crime, transport crashes, suicide attempts, and unnatural-cause mortality. 

Sweden’s ADHD medication use has soared. From 2006 to 2020, children’s use rose almost fivefold, and adults' use more than tenfold. This places Sweden among the highest globally in ADHD prescriptions. 

Research indicates that rising prescription rates are due to changes in diagnostic criteria and their interpretation, parental perception, and greater awareness of ADHD, rather than an actual increase in its prevalence. 

Sweden has a single-payer health insurance system that covers virtually its entire population, as well as a system of national registers that link health care records to other population databases.  

The Study:

A research team based in Sweden used that data to explore how the impact of ADHD medication on self-harm, injuries, traffic crashes, and crime has evolved with the dramatic increase in ADHD prescription rates. The team hypothesized that effects would decrease as medications were prescribed to a broader group of patients, including those with fewer impairments and risky behaviors who might not derive as much benefit from pharmacotherapy. 

The team identified all individuals aged 4 to 64 who were prescribed ADHD medication and living in Sweden in the fifteen years from 2006 through 2020. From this base cohort, they selected four specific cohorts for self-harm, unintentional injury, traffic crashes, and crime, consisting of individuals who experienced at least one relevant event during the study period. 

They used a self-controlled case series (SCCS) design to explore the link between ADHD medication use and outcomes. This approach allows individuals to serve as their own controls, accounting for confounders like genetics, socioeconomic status, or other constant characteristics during follow-up. 

A non-treatment period was defined as a gap of 30 days or more between two consecutive treatment periods. To examine the link between ADHD medication use and outcomes, the team divided follow-up time into consecutive periods for each individual. A new period began after a treatment switch. They estimated incidence rate ratios (IRRs) to compare the outcome event rates during medicated periods with non-medicated periods for the same individual. 

The team examined how ADHD medication outcomes varied with prescription prevalence across three periods: 2006-2010, 2011-2015, and 2016-2020, during which ADHD medication use continuously increased. 

The overall cohort encompassed almost a quarter million ADHD medication users: just over 57,000 for 2006-2010, just over 127,000 for 2011-2015, and slightly over 200,000 for 2016-2020. 

The Results:

ADHD medication use was linked to significantly lower rates of all studied outcomes during the study period. However, as prescription rates increased five to tenfold in the population, the strongest association for reduction in self-harm was observed between 2006 to 2010 (23% reduction in incidence rate) and was slightly reduced (below 20%) in the two more recent periods, though this change was not statistically significant.  

On the other hand, there was a significant decreasing trend in the reduction of incidence rate ratios for unintentional injury, with a 13% reduction in incidence rate in 2006-2010 decreasing over the two more recent periods to half that amount, 7%. For traffic crashes, a 29% reduction in incidence rate significantly diminished by more than half, to 13%. For crime, a 27% reduction in incidence rate from medication use significantly declined to 16%. 

When considering methylphenidate prescriptions only, these effects were partially attenuated for crime. A 28% reduction in the incidence rate for crime in 2006-2010 dropped to 19% in the two most recent periods, but the trend was not statistically significant. Nevertheless, there were no significant differences from the results in the larger cohort in any of the other categories.   

The Interpretation:

These outcomes were consistent with the team’s hypothesis. The researchers concluded, “While ADHD medications are consistently associated with reduced risk of serious real-world outcomes, the magnitude of these associations have decreased over time alongside rising prescription rates. This underscores the importance of continuously evaluating medication use in different patient populations.” 

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