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December 16, 2024
An international team of researchers has carefully examined the best current evidence and found strong evidence for an association between asthma and ADHD by combining a meta-analysis of prior data with a new analysis of the Swedish population.
The Method:
The meta-analysis identified 46 datasets with a total of more than 3.3 million persons. It computed an unadjusted (odds)'s ratio (OR) of 1.7, which indicates that ADHD patients have about twice the risk of developing asthma compared with people without ADHD. Limiting the meta-analysis to studies that adjusted for confounding factors, 30 datasets with more than a third of a million participants still led to an adjusted (odds)' ratio of 1.5 (95% CI 1.4 - 1.7). The likelihood of obtaining this result by chance in such a large sample would be less than one in ten thousand.
When the team further checked this result against the results for the Swedish population of more than one and a half million persons, the (odds) ratio was almost identical to 1.6. Adjusting for confounding factors reduced it to 1.5 (95% CI 1.41 - 1.48). That means the findings are very robust: asthma and ADHD are associated, with an (odds)'ratio of 1.5, after adjusting for confounding factors.
What does this small but statistically very reliable association between asthma and ADHD mean?
For researchers, it suggests that the two disorders may have common risk factors and that the search for these shared risk factors might lead to improved treatments. These risk factors might also be shared with two other somatic conditions for which ADHD patients are at increased risk: obesity and eczema. Common inflammatory processes may account for this overlap among disorders.
Conclusion:
Clinicians should be aware that children with asthma have an increased risk for ADHD, although, given the small association, systematic screening may not be warranted. But given that ADHD might interfere with asthma medication compliance, the disorder should be considered among noncompliant youth, especially among those who show other evidence of inattention, poor memory, or disorganization.
Samuele Cortese, Shihua Sun, Junhua Zhang, Esha Sharma,Zheng Chang, Ralf Kuja-Halkola, Catarina Almqvist, Henrik Larsson, Stephen VFaraone, "Association between attention deficit hyperactivity disorder andasthma: a systematic review and meta-analysis and a Swedish population-basedstudy," Lancet Psychiatry, Published online July 24, 2018 http://dx.doi.org/10.1016/S2215-0366(18)30224-4.
A new study in the respected journal PLOS One analyzes data from the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) to examine trends in the incidence, prevalence, and disability-adjusted life-years associated with ADHD among adolescents and young adults aged 10 to 24 years between 1990 and 2021.
The GBD 2021, released by the Institute for Health Metrics and Evaluation (U.S.), is a comprehensive global analysis of 371 diseases, injuries, and risk factors – such as ADHD – across 204 countries from 1990 to 2021. Its open-source data are publicly available.
First, a distinction. Incidence measures the number of new cases of a disease that develop in a specific population each year. Prevalence measures the total number of existing cases – both new and pre-existing – in a population each year.
The estimated global incidence of ADHD declined marginally from 12.61 per 100,000 population in 1990 to 11.89 per 100,000 population in 2021, representing an average annual decrease of 0.6% in age-standardized incidence. The rates observed were comparable between males and females.
Regional trends varied: Western Europe had the highest rise in ADHD incidence (0.5% annually), while North Africa and the Middle East saw the largest drop (0.7% annually). Overall, a higher Socio-Demographic Index (SDI) is linked to a greater incidence, although it is far from a perfect fit. Nationally, showed the highest increase in ADHD incidence (1.15% annually), while Qatar showed the largest decrease with an annualized reduction of 1.77%.
The estimated global prevalence of ADHD declined marginally from 2.38% in 1990 to 2.17% in 2021. Again, the decline was similar for males and females, and across all age groups (10-14, 15-19, 20-24). Higher SDI was associated with higher prevalence, but inconsistently.
Disability-adjusted life-years (DALYs) combine years lost from early death and years lived with disability to measure disease burden. Globally, the age-standardized DALYs rate for ADHD decreased slightly from 30.3 per 100,000 population to 26.6 per 100,000 population, for an average annual decline of 0.6%. The decline occurred across age groups and was similar between males and females.
The authors concluded that ADHD rates and related health burdens have generally declined over the past quarter century, though recent patterns are less consistent due to factors like socioeconomic changes and evolving diagnostic standards. Continued research is needed to improve the accuracy and accessibility of ADHD diagnosis and treatment to further reduce its global impact.
Take-Away:
The broader takeaway is one of cautious reassurance. Despite rising public awareness and diagnosis rates in many Western countries, the global picture over 25 years shows a gentle decline in ADHD burden among young people — not a crisis of escalating proportions. That said, the variation between regions suggests that access to diagnosis, cultural factors, and reporting standards are shaping the numbers as much as underlying biology. Progress is real but uneven, and the work of improving equitable access to diagnosis and care is far from finished.
The first few weeks of life are the time when babies are most vulnerable to seizures (known as neonatal seizures). This is partly because of events that can occur during birth, and partly because the newborn brain is naturally in a more excitable state than a mature brain, making it more prone to seizure activity.
Seizures affect roughly 1 to 3 in every 1,000 full-term babies born, and the rate is considerably higher in premature babies, at around 11 to 14 per 1,000. In most cases, seizures at this age are triggered by a specific event or injury affecting the brain. In full-term newborns, the most common cause is a condition called hypoxic-ischemic encephalopathy (HIE), which occurs when the brain is deprived of adequate oxygen and blood flow around the time of birth. Other causes include genetic or metabolic conditions, stroke, bleeding in the brain, and structural abnormalities in how the brain developed. In very premature babies, bleeding into the fluid-filled spaces of the brain (known as intraventricular hemorrhage) is the leading culprit.
Diagnosing seizures in newborns is tricky because many normal or abnormal movements and behaviors in this age group can look like seizures without actually being them. For this reason, monitoring the baby’s brain activity using an electroencephalogram (EEG) – a test that records electrical signals in the brain – is essential to confirm whether a seizure is truly occurring.
Sweden’s single-payer health system provides universal coverage, with national registers linking healthcare and population data. Researchers tracked infants with EEG/aEEG-confirmed seizures born between 2009 and 2020 and compared them to controls without neonatal seizures.
Altogether, 1062 infants with neonatal seizures were matched with 5310 controls.
The team adjusted for birth, mode of delivery, sex, birth weight, and Apgar scores – quick, standardized assessments used to evaluate newborns’ health minutes after birth.
With these adjustments, infants who had neonatal seizures were twice as likely to subsequently be diagnosed with ADHD and three times as likely to be subsequently diagnosed with autism spectrum disorder.
The authors emphasized that because the study was observational, it cannot demonstrate a direct cause-and-effect relationship between neonatal seizures and outcomes. Factors like seizure frequency, genetics, and socioeconomic status are thought to significantly impact the prognosis of affected children, but these could not be included in this study due to data limitations.
Background:
There are currently few long-term treatment options for adult ADHD. Psychostimulants can help reduce symptoms, but their benefits rely on availability, continued use, and are not easily tolerated by some. Cognitive-behavioral therapies have also proven to be helpful, but access is limited because they must be provided by trained specialists. These challenges highlight the need to explore alternative interventions that could provide cognitive and behavioral improvements with fewer side effects.
Exercise has shown potential as a nonclinical intervention for ADHD. Previous research indicates that physical activity can increase cortical volume, enhance brain activation, and boost connectivity in cognitive regions, as well as raise dopamine and norepinephrine levels – effects similar to psychostimulants. Research in children and teens with ADHD has found that both regular exercise programs and even single workout sessions can improve executive functions (mental skills like planning and self-control) and reduce core ADHD symptoms. But whether exercise helps adults with ADHD has remained an open question.
Study:
A Chinese sports medicine research team set out to answer this by reviewing all available peer-reviewed studies on exercise and adult ADHD. They found so few studies on regular exercise programs – only four total, and three of those were small pilot studies just testing whether the approach was feasible – that they couldn’t draw firm conclusions about long-term exercise interventions.
However, they were able to analyze four moderate-to-high-quality studies involving 152 adults with ADHD that tested single exercise sessions. The combined results showed moderate improvements in inhibitory control (the ability to resist impulses and stay focused). Adults not taking medication showed large improvements.
When they looked at four studies involving 170 adults, they found small but consistent improvements in core ADHD symptoms after single exercise sessions. There was little to no variation (heterogeneity) in individual study outcomes, and no sign of publication bias.
Results:
The team concluded, “Overall, these findings offer preliminary evidence on the potential role of exercise as a helpful strategy in the management of adult ADHD,” but cautioned that more well-designed randomized controlled trials are needed to determine the efficacy of both acute and chronic exercise interventions for adult ADHD, with particular emphasis placed on determining the best “prescription” for exercise – what type, how intense, and how often.
They also noted that most existing research has focused narrowly on attention and impulse control, while other important mental abilities like working memory and mental flexibility remain largely unexplored.
Take-Away:
The takeaway here is practical and accessible: you don't need a long-term fitness program to get a cognitive bump from exercise if you have ADHD. Even a single session appears to help — particularly with impulse control. While the research base is still thin and we don't yet know the ideal exercise "prescription," the risk-benefit calculation is hard to argue with. For adults with ADHD who can't access medication or therapy, or who simply want an additional tool, breaking a sweat may be worth building into the routine.
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