December 4, 2023

Meta-analysis finds association between postnatal secondhand smoke and ADHD

Secondhand smoke (SHS) is tobacco smoke inhaled by nonsmokers sharing enclosed spaces with smokers. It contains well over two hundred toxic chemicals, including some toxic metals known to cause serious harm to humans. It is among the most common indoor air pollutants worldwide, with roughly two in five children exposed.

Until now, studies have focused primarily on maternal smoking before childbirth. A Chinese research team set out to explore what, if any, association there might be between childhood exposure to SHS and ADHD. They conducted a comprehensive search of the peer-reviewed literature and identified nine studies with a combined total of over a hundred thousand participants that looked for such effects. The studies were carried out in the United States, Germany, Spain, and the Republic of Korea.

Merging these studies into a meta-analysis, the team found that children exposed to secondhand smoke were 60 percent more likely to develop ADHD. The same overall pattern held true on all three continents.

A further meta-analysis of four of the studies with over 12,000 participants found children exposed to secondhand smoke were 33% more likely to exhibit conduct problems.

The authors concluded, "The results of our meta-analysis suggest that postnatal exposure to SHS may be associated with ADHD in children. Exposure to SHS can also lead to a variety of adverse behavioral outcomes in children. Therefore, parents should stop smoking to create a good growing environment for their children. Further prospective studies should fully adjust for potential confounding factors to determine whether there is a causal relationship between SHS and ADHD."

Anyan Huang, Kusheng Wu, Zemin Cai, Yuhang Lin, Xuanzhi Zhang, and Yanhong Huang, "Association between postnatal second-hand smoke exposure and ADHD in children: a systematic review and meta-analysis," EnvironmentalScience and Pollution Research (2020), https://doi.org/10.1007/s11356-020-11269-y.

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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

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

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