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July 2, 2025

Swedish nationwide population study identifies top predictors of ADHD diagnoses among preschoolers

Most preschool-aged children diagnosed with ADHD also exhibit comorbid mental or developmental conditions. Long-term studies following these children into adulthood have demonstrated that higher severity of ADHD symptoms in early childhood is associated with a more persistent course of ADHD. 

The Study: 

Sweden has a single-payer national health insurance system that covers virtually all residents, facilitating nationwide population studies. An international study team (US, Brazil, Sweden) searched national registers for predictors of ADHD diagnoses among all 631,695 surviving and non-emigrating preschoolers born from 2001 through 2007.  

Preschool ADHD was defined by diagnosis or prescription of ADHD medications issued to toddlers aged three through five years old.  

Predictors were conditions diagnosed prior to the ADHD diagnosis. 

A total of 1,686 (2.7%) preschoolers were diagnosed with ADHD, with the mean age at diagnosis being 4.6 years. 

The Numbers:

Adjusting for sex and birth year, the team reported the following predictors, in order of magnitude: 

  • Previous diagnosis of autism spectrum disorder increased subsequent likelihood of ADHD diagnosis twentyfold. 
  • Previous diagnosis of intellectual disability increased subsequent likelihood of ADHD diagnosis fifteenfold. 
  • Previous diagnosis of speech/language developmental disorders and learning disorders, as well as motor and tic disorders, increased subsequent likelihood of ADHD diagnosis thirteen-fold. 
  • Previous diagnosis of sleep disorders increased subsequent likelihood of ADHD diagnosis fivefold. 
  • Previous diagnosis of feeding and eating disorders increased subsequent likelihood of ADHD diagnosis almost fourfold. 
  • Previous diagnosis of gastroesophageal reflux disease (GERD) increased subsequent likelihood of ADHD diagnosis 3.5-fold. 
  • Previous diagnosis of asthma increased subsequent likelihood of ADHD diagnosis 2.4-fold. 
  • Previous diagnosis of allergic rhinitis increased subsequent likelihood of ADHD diagnosis by 70%. 
  • Previous diagnosis of atopic dermatitis or unintentional injuries increased subsequent likelihood of ADHD diagnosis by 50%. 

The Conclusion: 

This large population study underscores that many conditions present in early childhood can help predict an ADHD diagnosis in preschoolers. Recognizing these risk factors early may aid in identifying and addressing ADHD sooner, hopefully improving outcomes for children as they grow

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South Korean Nationwide Population Study Finds ADHD Diagnosis Associated With Greater Odds of Subsequent Diagnosis of Major Psychiatric Disorders

Background: 

ADHD is commonly accompanied by psychiatric comorbidities that complicate its diagnosis and treatment. Roughly two out of three affected children and adolescents have one or more comorbid psychiatric disorder. 

Because the peak age of ADHD onset is typically a decade or more earlier than those for schizophrenia, depressive disorder, or bipolar disorder, it is essential to explore these comorbidities over an extended period. Populations studies help researchers identify broader patterns and trends within an entire population and includes adults as well as children. This type of study provides unique insights into the population at large, rather than a sample group.

In earlier studies the maximum follow-up period was twelve years, insufficient in view of the roughly ten years between onset of ADHD and onset of major psychiatric disorders. Also, previous nationwide population studies have included less than 150,000 participants. 

The Study:

This study, relying on data from South Korea’s universal single-payer health insurance system, included over one and a half million individuals. Persons previously diagnosed with depression, bipolar disorder, tic disorder, or schizophrenia were excluded. 

382,434 individuals had been diagnosed with ADHD, while 1,169,279 were without an ADHD diagnosis.  

Propensity score matching ensured that potential confounders, both sociodemographic and clinical, were equalized for the ADHD and control groups. After matching, there were 353,898 individuals in each group. 

After these adjustments, individuals in the ADHD group were at least an order of magnitude more likely to subsequently be diagnosed with  psychiatric disorders than their peers without an ADHD diagnosis: 

  • Almost eleven times more likely to be diagnosed with depressive disorder. 
  • More than twelve times as likely to be diagnosed with bipolar disorder. 
  • Over thirteen times more likely to be diagnosed with schizophrenia. 

Conclusion:

The Korean study team concluded, “Overall, our findings suggest that upon prolonged examination, the risk of subsequent diagnoses of other psychiatric disorders in individuals with ADHD appears to be higher than that reported previously. … Therefore, patients with ADHD should be carefully screened for the presence of other psychiatric symptoms on a regular basis from an earlier age … It is advisable to have a follow-up period extending beyond 10 years to sufficiently identify the occurrence of comorbid disorders in patients with ADHD.” 

February 18, 2025
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NEWS STUDY: Focus Group Study of Primary Teachers' Perceptions of Children with ADHD who Struggle Socially

Children with ADHD often face challenges in social interactions, leading to long-term consequences if not properly addressed. While various interventions exist, many fail to consider the broader social context in which these children interact. A recent study conducted in Bergen, Norway, explored how primary school teachers perceive their role in supporting children with ADHD who struggle socially and the strategies they use to assist them.

Investigating Teacher Perspectives

Researchers conducted semi-structured interviews with five focus groups of primary school teachers. Using reflexive thematic analysis, they identified two major themes:

  1. Understanding Individual Needs in Context – Teachers emphasized that every child is unique, and ADHD should not define a student's social struggles. They highlighted the importance of considering the child’s specific social challenges within their broader environment.
  2. Adapting Strategies Through Continuous Assessment – Teachers described their work as a dynamic and flexible process, adjusting their approaches based on the child's evolving needs. This included providing subtle background support as well as direct guidance in social interactions.
A Personalized Approach to Social Support

Rather than relying on standardized interventions, teachers tailored their strategies to foster an inclusive and supportive social environment. Their methods included both active participation in social situations and behind-the-scenes efforts to encourage peer inclusion and understanding.

Rethinking ADHD and Social Development

This study underscores the need to move beyond labels and recognize children with ADHD as individuals with distinct social needs. Teachers play a crucial role in shaping these children’s experiences, using flexible and personalized approaches to promote positive social interactions. By integrating social context and individualized support, educators can help children with ADHD build meaningful connections and navigate their social world more effectively.

February 12, 2025
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Meta-analysis Reports Mild Association Between Junk Food and ADHD in Children and Adolescents

Background:

“Junk food” is a shorthand for highly processed foods and beverages with low nutritional value and dietary fiber that are typically high in added sugars, starches, and additives intended to boost flavor, color, texture, and shelf life. 

Previous studies examining such an association have yielded contradictory or inconclusive results. 

Method:

An Iranian research team therefore conducted a systematic search of the peer-reviewed medical literature to run a meta-analysis of data from studies published to date. 

Meta-analysis of nine studies, with a combined total of over 58,000 persons, found that children and adolescents who consumed more junk foods were about 25% more likely to exhibit ADHD symptoms. Restricting this to the seven studies rated good or high quality (7+ out of 10 on the Newcastle–Ottawa Quality Assessment Scale) produced the same exact outcome.  

The result was consistent across individual studies, with low heterogeneity. There was no sign of publication bias. 

Breaking this down by subtype of junk food: 

  • Combining six studies with over 52,000 total participants, sugary beverages including soft drinks were associated with the same 25% increase in ADHD symptoms. Heterogeneity was moderate. 
  • Combining three studies with over 1,600 total participants, solid sweets and candies were associated with a greater than one-third increase in ADHD symptoms. There was no variation in outcome among the three studies. 
  • Combining three studies with over 22,000 total participants, other heavily processed foods were associated with a 17% increase in ADHD symptoms. Again, there was no variation in outcome among the three studies. 

The team used data adjusted for confounders: “We used … adjusted OR [odds ratios] for the meta-analysis.” 

This outcome, while suggestive, should be interpreted cautiously due to limitations: 

  • ADHD symptoms were rated by parents or caregivers using standardized questionnaires. ADHD diagnoses by qualified medical professionals are the gold standard, and were not used. 
  • Junk food consumption was likewise estimated by parents or caregivers through answers to questionnaires. There was no direct measurement of consumption. Answers were categorical, making it impossible to look for dose-response relationships. 
  • Even if the association holds with further study, it is unclear whether impulsivity associated with ADHD leads to greater consumption of junk foods, or junk food consumption somehow harms development of the nervous system, or the relationship is due to unmeasured confounding by other variables.   

Conclusion:

The team concluded, “This meta-analysis of observational studies adds strong evidence linking the consumption of junk foods, particularly, sweetened beverages/soft drinks and sweets/candies, with ADHD symptoms in children and adolescents. However, the study did not evaluate the causality of the relationship. So, to identify causality and the dose–response effects of junk food consumption on the development of ADHD, further studies are warranted.” 

February 10, 2025
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Meta-analysis Finds Young People with ADHD Are More Likely to be Lonely Than Non-ADHD Peers

A research team based in London (U.K.) has just released the first meta-analysis to explore whether young people with ADHD experience greater loneliness compared to young people without ADHD.  

There has been a lot of research into social-emotional functioning in ADHD focusing on social networks and peer functioning problems, with little inquiry into young people’s experience of and satisfaction with their relationships.  

The team noted, “This is an important distinction as loneliness, or perceived social isolation, is the subjective feeling of distress due to a perceived deficit in the quantity and quality of one’s social relationships. An individual may be objectively socially isolated but may not have a negative perception of their relationships and equally, someone may find their social relationships lacking despite having a large social network … As loneliness and social isolation (e.g., number of friends or size of social network) have been found to be weakly correlated, it is important to capture the loneliness experience of the young person rather than relying on just the objective measures of social isolation.” 

Loneliness is a public health concern, as it predicts increases in depression, anxiety, self-harm, and suicidal ideation. 

The team performed a systematic search of the peer-reviewed medical literature to identify quantitative studies that compared loneliness among young people under 25 diagnosed with ADHD with non-ADHD matched controls. The search excluded studies in which participants had intellectual disabilities and/or other neurodevelopmental conditions such as autism spectrum disorder. 

Meta-analysis of 15 studies with a combined 6,281 participants found that young people with ADHD experienced greater loneliness than their non-ADHD peers with a small-to-medium effect size. There was no sign of publication bias, but very high variation (heterogeneity) in outcomes across the studies.  

Removing one small outlier study, the remaining 14 studies with 6,099 participants brought heterogeneity down to moderate levels, and yielded a medium effect size increase in perceived loneliness among young people with ADHD.  

Conclusion: 

“The findings in this study highlight the importance of understanding loneliness in this population as young people with ADHD report significantly higher levels of loneliness compared to their non-ADHD peers, and loneliness in young people with ADHD is associated with a range of mental health difficulties,” the researchers stated. “More resources should be focused on loneliness as a separate construct from social isolation and peer difficulties.” 

February 7, 2025
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Exploring the Impact of ADHD Treatment on Empathy and Narcissism

A recent study published in Alpha Psychiatry sheds light on the connection between ADHD, empathy, and narcissistic traits. Researchers aimed to evaluate how pharmacological treatments—specifically psychostimulants—affect empathy deficits and pathological narcissism in adults with ADHD. These findings could have important implications for enhancing treatment outcomes and improving social functioning.

Study Overview:
The study involved 75 adult ADHD patients who were treated with either methylphenidate or atomoxetine. Researchers assessed levels of narcissistic traits and empathy using validated tools such as the Pathological Narcissism Inventory (PNI) and the Empathy Quotient (EQ). Measurements were taken before treatment and after three months of therapy.

Key Findings:

  • Narcissistic Traits: Patients showed a significant reduction in grandiosity and vulnerability scores, with total PNI scores decreasing after treatment.
  • Empathy Levels: Empathy improved significantly, as reflected by higher post-treatment EQ scores.
  • Overall Impact: These changes suggest that psychostimulant treatment positively influences brain circuits related to empathy and narcissistic tendencies, potentially leading to better interpersonal relationships.

Why It Matters:
Adults with ADHD often struggle with social interactions, partly due to empathy deficits and personality traits like narcissism. By addressing these challenges through psychostimulant treatment, patients may experience better social and emotional well-being. This study underscores the importance of viewing ADHD treatment as not just a way to manage symptoms but also a means to improve overall quality of life.

Takeaway
Effective ADHD treatment goes beyond managing attention and hyperactivity. By improving empathy and reducing narcissistic traits, psychostimulants can foster healthier relationships and enhance social functioning. This research highlights the need for comprehensive care that considers the broader psychological and interpersonal effects of ADHD.

February 4, 2025
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Meta-analysis Suggests Music Training May Be a Useful Tool for Inhibition Control

According to Fosco et al. (2019), “Inhibitory control has long been considered a central neurocognitive process in ADHD, with ADHD groups typically showing medium-sized impairments relative to their typically-developing peers on common inhibition paradigms.” 

Learning to play a musical instrument requires effective coordination of physical movements and sound signals to produce music. Musical training involves repetitive practice, perfecting connections between perceptions, muscular actions, and cognition. 

Noting that listening to music activates the brain’s reward circuits in both children and adults, that “Being internally motivated during learning experiences increases learning capacity and efficiency, and this greater engagement is reflected in increased electrical brain activity following musical training,” and that “Training music in a social environment increases positive feelings of bonding through shared emotions and group synchrony,” a Montreal-based research team carried out a systematic review and meta-analysis of the peer-reviewed medical literature from 1980 to 2023 to learn what effect music training might have on inhibition control. 

Outcomes:

The team found eight randomized controlled trials (RCTs) and 14 other longitudinal studies that met search criteria, including: 

  • Music training was with neurotypical children and adolescents 
  • The experimental group was trained using music alone 
  • Studies were longitudinal, with either active or passive controls 
  • Studies included a performance-based inhibition control measure as an outcome 

Meta-analysis of all 22 longitudinal studies with a combined total of 1,734 participants yielded a small-to-medium effect size improvement in inhibitory control. Variation (heterogeneity) in outcomes between individual studies was small, and there was no sign of publication bias. Restricting the analysis to the eight RCTs with a combined total of 641 participants, however, yielded a medium-to-large effect size improvement, with negligible heterogeneity, meaning the outcome was consistent across RCTs. 

The Take-Away: The team concluded, “Music training plays a privileged role compared to other activities (sports, visual arts, drama) in improving children’s executive functioning, with a particular effect on inhibition control.”   I cannot, however, recommend this as a therapy for ADHD until RCTs show it reduces symptoms of ADHD and/or real world impairments associated with the disorder.

February 3, 2025
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Population Study Finds No ADHD- or ASD- Related Benefits From Eating Organic Food During Pregnancy

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.”

January 27, 2025
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Meta-analysis Finds Little or No Link Between Assisted Reproductive Technologies and ADHD

Background:

Infertility affects about one in six couples worldwide. To address this, medical experts have developed Assisted Reproductive Technologies (ART), including In Vitro Fertilization (IVF) with or without Intra-Cytoplasmic Sperm Injection (ICSI).

Some research suggests that children conceived through ART might have higher rates of intellectual disabilities, cerebral palsy, cancer, and neurological issues compared to children conceived naturally. However, studies looking at a possible link between ART and ADHD have produced mixed and conflicting results.

Until now, there hasn’t been a meta-analysis examining the connection between ART and ADHD. A South Korean research team has conducted the first systematic review and meta-analysis on this topic. Their final analysis included eight studies with a total of over ten million participants, comprising six cohort studies and two cross-sectional studies.

Method:

The research focused on two types of studies:

  1. Cohort Studies: These follow two groups (one exposed to ART and one not exposed) over time to see if a specific outcome, like ADHD, occurs.
  2. Cross-Sectional Studies: These compare the prevalence of ADHD at a single point in time between those exposed to ART and those who weren’t.

Both types of studies are observational, meaning they don’t involve controlled experiments and can be influenced by confounding factors.  So they can document interesting associations, not causality.  The studie were mostly large-scale national studies and used clinical ADHD diagnoses.

Key Findings:
  • Cohort Studies: Meta-analysis of six cohort studies, involving nearly 8 million participants, found no link between ART and ADHD. However, there was high variability (heterogeneity) in the results from individual studies.
  • Cross-Sectional Studies: Meta-analysis of two cross-sectional studies, covering over 2.3 million participants, also found no link between ART and ADHD. Heterogeneity was moderate.
  • Adjustment for Confounding: A separate analysis of three studies that adjusted for confounding factors (like socioeconomic status or parental health) involved more than 7.5 million participants. It found a very small association, with ART-conceived children being 8% more likely to develop ADHD. There was no variability among these studies.
Conclusion:

The researchers concluded that while there may be a small association between ART and ADHD, the effect is minimal, and the results are influenced by differences in study designs. They advised interpreting these findings with caution, noting, “The limited effect size and inherent heterogeneity underscore the need for cautious interpretation.”

January 24, 2025
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Taiwan nationwide population study documents link between ADHD and periodontitis in adolescents

Population Study Documents Link Between ADHD and Periodontitis in Adolescents

Background:

Periodontitis, commonly known as gum disease, is a condition where the gums become inflamed. If untreated, it can cause the gums to pull back from the teeth, exposing their base, which may eventually lead to loose teeth or tooth loss. While this condition mostly affects adults, it’s also common among teens who don’t floss or brush their teeth properly.

Until now, only a few small studies have looked at a possible link between ADHD and gum disease. A team in Taiwan recently conducted a nationwide study to explore this connection.

Taiwan has a universal health insurance program, introduced in 1995, that provides medical care to nearly all (99.7%) residents. The Taiwan National Health Research Database collects and oversees all insurance claims, making it an excellent resource for large-scale studies.

Methods:

The researchers used the database to identify teens aged 12 to 19 with ADHD (diagnosed by a psychiatrist) who had no history of gum disease between 2001 and 2011. These teens made up the ADHD group. They matched each ADHD participant with four teens who didn’t have ADHD or gum disease, creating a control group. The groups were matched by age, gender, enrollment date, family income, place of residence, and other health conditions (like obesity, diabetes, smoking, depression, and substance use).

All diagnoses of gum disease were confirmed by board-certified dentists.

The study included:

  • 16,211 teens with ADHD
  • 162,110 matched controls
Key Findings:
  • Teens with ADHD were 2.3 times more likely to develop gum disease than those in the control group without ADHD.
  • There were no significant differences between boys and girls or among teens from different income levels (low, medium, or high).
  • ADHD medications, mainly methylphenidate, didn’t affect the likelihood of developing gum disease. This was true for both short-term and long-term users compared to non-users.
Conclusion:

The researchers concluded that teens with ADHD have a higher risk of developing gum disease later on, even after accounting for other risk factors like smoking, diabetes, and depression. They stated, “ADHD is an independent risk factor for developing periodontitis.”

January 23, 2025
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Meta-Analysis: Physical Activity for Children and Adolescents with ADHD

Attention Deficit Hyperactivity Disorder (ADHD) is a prevalent neurodevelopmental disorder that significantly impacts children’s academic performance, social interactions, and overall quality of life (QoL). While medication is the standard treatment, it often comes with side effects and may not always provide sufficient benefits. A new systematic review and meta-analysis aims to investigate whether physical activity can offer a viable and effective alternative or complement to medication.

About the Study
This protocol, developed in line with the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols (PRISMA) guidelines, focuses on randomized clinical trials involving children and adolescents (ages 3–18) diagnosed with ADHD or hyperkinetic disorder. The study's goal is to evaluate the effects of physical activity on:

  • Quality of life (QoL)
  • Executive functions
  • ADHD symptoms
  • Functional impairments

Unlike earlier reviews, which often included non-randomized trials or imposed limits on activity types, this analysis takes a more robust and inclusive approach. It is the first of its kind to examine QoL as an outcome while also incorporating trial sequential analysis—a method to assess evidence strength over time.

Why Physical Activity?
Physical activity is believed to impact the same brain systems targeted by ADHD medications, particularly the catecholaminergic system. This overlap suggests that exercise could play a key role in managing symptoms, potentially reducing reliance on medication or enhancing its effects.

Methodology Highlights

  • The review will adhere to principles outlined in the Cochrane Handbook for Systematic Reviews of Interventions.
  • It incorporates the latest research and focuses on randomized trials to ensure high-quality evidence.
  • No restrictions are placed on the frequency or intensity of physical activity interventions, making the findings broadly applicable.

Significance and Dissemination
The results of this systematic review will provide critical insights into how physical activity could improve outcomes for children and adolescents with ADHD. It is also notable as the first review in this field to prioritize quality of life—a crucial, often-overlooked measure of treatment success.

The findings will be published in peer-reviewed journals and presented at relevant conferences to inform clinicians, educators, and families.

Conclusion
As concerns about the limitations of ADHD medication grow, exploring alternatives like physical activity becomes increasingly important. This systematic review has the potential to shape future treatment strategies, offering children with ADHD a chance for better symptom management and a higher quality of life.

January 21, 2025
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