January 20, 2022
Taiwan's National Birth Registration database tracks every birth. Using all entries from 2005, random sampling was used to create the Taiwan Birth Cohort Study of 24,200 mother-infant pairs, which were geographically distributed and represented 12 percent of all births.
As this was an eight-year longitudinal study, there were dropouts, and 17,256 pairs completed the study. After excluding cases with fetal distress, smoking or alcohol use during pregnancy, and missing information on covariates, the final study population was 16,376.
Participants' addresses during gestation were geocoded to the township level, and local air pollution data was retrieved for the years 2004 to 2006 from air quality monitoring stations administered by Taiwan's Environmental Protection Administration. Every hour, each station records levels of nitric oxide (NO), nitrogen dioxide (NO2), nitrogen oxides (NOx), sulfur dioxide (SO2), carbon monoxide (CO), and particulate matter of diameter 10 μm or less (PM10).
The Taiwanese research team addressed several potential confounding factors: sex, maternal age, delivery method (cesarean section or not), birth in summer (June-August), urban or rural residence, and annual household income.
Because ADHD is primarily observable as hyperactivity rather than inattention among young children, the team focused on relating symptoms of hyperactivity to levels of air pollutants.
After adjusting for covariates, the team found no significant association between PM10 and SO2 levels and hyperactivity disorder. Nitrogen oxide levels, on the other hand, were associated with more than 25 percent higher odds of hyperactivity.
Breaking that down further, they found no significant association with NO2, and that the 25 percent higher odds were exclusive with nitric oxide (NO), a pollutant emitted by internal combustion engines in cars, trucks, and busses. NO is a free radical, meaning it has an unpaired electron that can damage the body because of its strong chemical reactivity.
The authors noted, "Our study has some limitations. First, hyperactivity was diagnosed based on a parent-reported physician or specialist diagnosis. Although we did not inquire which specialists made these diagnoses, they must have been a pediatrician, psychiatrist, or special education teacher. ... Second, the calculated exposure to ambient air pollutants was not an accurate personal exposure because it did not take indoor air pollutant levels and time-activity patterns into consideration. Applying personal environmental monitoring in such a large sample is impractical, especially when the subjects are pregnant."
Nevertheless, they emphasized, "this is the first study attempting to discover which component of NOx is more critical to the development of hyperactivity in offspring."
Ping Shih, Ching-Chun Huang, Shih-Chun Pan, Tung-Luang Chiang Yue Leon Guo, "Hyperactivity disorder in children related to traffic-based air pollution during pregnancy," Environmental Research(2020),188: 109588, https://doi.org/10.1016/j.envres.2020.109588.
There has been consistent evidence of an association between ADHD and subjectively reported sleep problems even in patients not medicated for the disorder. There have also been studies using wrist-worn actigraphy (a wrist watch-like device that measures gross motor activity) and sleep lab-based polysomnography that measure objective sleep parameters.
What has been missing are large population-based cohort studies to explore the prevalence rates of different sleep disorders and medical prescriptions in ADHD.
Methods Used:
Sweden has a single-payer health insurance system and a series of national population registers that track virtually its entire population. Using the Swedish Total Population Register, a local research team created a cohort of all 6,470,658 persons born between 1945 and 2008. They linked this to the Swedish National Patient Register, which includes inpatient hospitalizations from 1975 to 2013, and outpatient specialist diagnoses from 2001 to 2013, to identify diagnoses of sleep disorders. They also linked to the Prescribed Drug Register, covering 2005 to 2013, to identify prescriptions for sleep medications.
Summary of Findings:
Overall, persons with ADHD were eight times more likely to be diagnosed with any sleep disorder relative to normally developing peers. Broken down by age, adolescents with ADHD were 16 times more likely to receive such diagnoses, young adults (18-30) twelve times more likely, children and mid-age adults (31-45) eight times more likely, and older adults six times more likely.
Broken down by specific sleep disorder diagnoses, relative to normally developing peers, persons with ADHD were:
As for sleep medication, relative to normally developing peers, persons with ADHD were:
Conclusion:
The team concluded, “Our findings also suggest that greater clinical attention should be directed towards addressing sleep problems in individuals with ADHD. This entails implementing proactive measures through sleep education programmes and providing both pharmacological and non-pharmacological approaches such as cognitive behavioural therapy and parental sleep training.”
Attention is a critical determinant of academic achievement, influencing domains such as language, literacy, and mathematics. To explore whether physical activity can improve attention in children with ADHD, an international team conducted a meta-analysis of peer-reviewed studies. The goal was to evaluate the impact of various physical activity regimens on attention-related outcomes in this population.
The researchers performed a comprehensive search of the medical literature to identify studies examining the effects of physical activity on attention in schoolchildren with ADHD. They included 10 studies with a total of 474 participants in their meta-analysis. The studies evaluated two main types of physical activity:
Additionally, they examined variations based on the frequency, duration, and type of control groups used in the studies. To assess consistency, they also analyzed heterogeneity (variability of outcomes) and checked for potential publication bias.
Key findings from the meta-analysis include:
The authors concluded that mentally engaging exercise is more effective than aerobic exercise in improving attention problems in schoolchildren with ADHD. Furthermore, higher frequency and longer duration of physical activity do not necessarily yield better outcomes.
This research underscores the importance of tailoring physical activity interventions to emphasize cognitive engagement over intensity or duration. By refining strategies, educators and parents can better support children with ADHD in achieving academic success. But take note: given the results from controlled studies, it seems clear that if there is a positive effect of exercise, it is very small so should not replace standard treatments for ADHD.
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Previous studies have examined how stimulant medications affect the brain in controlled settings, but less is known about their impact in real-world conditions, where children may not always take their medication consistently or may combine it with other treatments. A new study leverages data from the Adolescent Brain Cognitive Development (ABCD) study to explore how real-world stimulant use impacts brain connectivity and ADHD symptoms over two years.
Changes in Brain Connectivity Researchers used brain imaging data from the ABCD study to examine the functional connectivity—communication between brain areas—of six regions within the striatum, a brain area involved in motivation and movement control. They focused on how stimulant use influenced connectivity between the striatum and other networks involved in executive functioning and visual-motor control.
The study found that stimulant exposure was linked to reduced connectivity between key striatal areas (such as the caudate and putamen) and large brain networks, including the frontoparietal and visual networks. These changes were more pronounced in children taking stimulants compared to those who were not medicated, as well as compared to typically developing children. Importantly, this reduction in connectivity seemed to regulate certain brain networks that are typically altered in children with ADHD.
Symptom Improvement In addition to brain changes, 14% of children taking stimulants experienced a significant reduction in ADHD symptoms over the two-year period. These children showed the strongest connectivity reductions between the right putamen and the visual network, suggesting that stimulant-induced connectivity changes may contribute to improvements in visual attentional control, which is a common challenge for children with ADHD.
Why This Matters This study is one of the first to examine how stimulant use in real-world conditions affects brain networks in children with ADHD over time. The findings suggest that stimulants may help normalize certain connectivity patterns associated with ADHD, particularly in networks related to attention and control. These insights could help clinicians better understand the potential long-term effects of stimulant treatment and guide personalized approaches to ADHD management.
Conclusion Stimulant medications appear to alter striatal-cortical connectivity in children with ADHD, with some changes linked to symptom improvement. This research highlights the potential for stimulant medications to impact brain networks in ways that support attention and control, highlighting the importance of understanding how real-world medication use influences ADHD treatment outcomes.
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