March 25, 2022

South Korean nationwide population study finds strong association between low birth weight and subsequent ADHD

Since 1989, South Korea has had a single-payer healthcare insurance system, the Korean National Health Insurance Service. This facilitates nationwide population studies.

A South Korean study team used the national health claims database to retroactively examine the relationship between birth weight and subsequent diagnosis of ADHD for all 2.36 million children born in the country between 2008 and 2012. After excluding children who had since died, who had missing birth weight records, missing income information, or who weighed under400 grams at birth, 2,143,652 children remained in the study cohort.

Gestational age at birth was not available, so could not be taken into consideration.

To reduce the impact of confounding factors, odds ratios were adjusted for sex, history of congenital or perinatal diseases, income, and birth year.

Children with more normal birth weights in the range of 2.5 to 4 kilograms were used as the reference group.

Children with birth weights greater than this reference group were found to be no more likely to develop ADHD than those in the reference group.

At the other end of the spectrum, children with birth weights under a kilogram were 2.2 times more likely to be diagnosed with ADHD than those in the reference group.

That dropped to 1.7 times more likely for those with birth weights from 1 to 1.5 kilograms; 1.5 times more likely in the 1.5-to-2-kilogram range, and 1.4 times more likely in the 2-to-2.5-kilogram range. This dose-response curve, accelerating steeply with lower birth weights, points to a strong association.

For autism spectrum disorder (ASD), the association was even stronger. Again, there was no significant association with higher-than-normal birth weight. But children in the 2-to-2.5-kilogram range were 1.9 times as likely to be diagnosed with ASD; those in the 1.5-to-2 kilogram tranche over three times as likely; those in the 1 to 1.5-kilogram tranche five and halftime as likely, and those under 1 kilogram over ten times as likely.

The authors concluded, "In this national cohort, infants with birth weights of < 2.5 kg were associated with ADHD and ASD, regardless of perinatal history. Children born with LBW [low birth weight] need detailed clinical follow-up."

In Gyu Song, Han-Suk Kim, Yoon-Minho, You-na Lim, Duk-Soo Moon, Seung Han Shin, Ee-Kyung Kim, Joonsik Park, Jeong Eun Shin, Jungho Han, and Ho SeonEun, "Association between birth weight and neurodevelopmental disorders assessed using the Korean National HealthInsurance Service claims data," Scientific Reports (2022)12:2080, published online,

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A recent study delved into the connection between fidgeting and cognitive performance in adults with Attention-Deficit/Hyperactivity Disorder. Recognizing that hyperactivity often manifests as fidgeting, the researchers sought to understand its role in attention and performance during cognitively demanding tasks. They designed a framework to quantify meaningful fidgeting variables using actigraphy devices.

(Note: Actigraphy is a non-invasive method of monitoring human rest/activity cycles. It involves the use of a small, wearable device called an actigraph or actimetry sensor, typically worn on the wrist, similar to a watch. The actigraph records movement data over extended periods, often days to weeks, to track sleep patterns, activity levels, and circadian rhythms. In this study, actigraphy devices were used to measure fidgeting by recording the participants' movements continuously during the cognitive task. This data provided objective, quantitative measures of fidgeting, allowing the researchers to analyze its relationship with attention and task performance.)

The study involved 70 adult participants aged 18-50, all diagnosed with ADHD. Participants underwent a thorough screening process, including clinical interviews and ADHD symptom ratings. The analysis revealed that fidgeting increased during correct trials, particularly in participants with consistent reaction times, suggesting that fidgeting helps sustain attention. Interestingly, fidgeting patterns varied between early and later trials, further highlighting its role in maintaining focus over time.

Additionally, a correlation analysis validated the relevance of the newly defined fidget variables with ADHD symptom severity. This finding suggests that fidgeting may act as a compensatory mechanism for individuals with ADHD, aiding in their ability to maintain attention during tasks requiring cognitive control.

This study provides valuable insights into the role of fidgeting in adults with ADHD, suggesting that it may help sustain attention during challenging cognitive tasks. By introducing and validating new fidget variables, the researchers hope to standardize future quantitative research in this area. Understanding the compensatory role of fidgeting can lead to better management strategies for ADHD, emphasizing the potential benefits of movement for maintaining focus.

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A recent study investigated the presence of autistic-like symptoms in children diagnosed with Attention Deficit/Hyperactivity Disorder (ADHD). Given the overlapping social difficulties in both ADHD and Autism Spectrum Disorder (ASD), distinguishing between the two disorders can be challenging. This study aims to pinpoint specific patterns of autistic symptoms in children with ADHD, comparing them to those with ASD using the Autism Diagnostic Observation Schedule, 2nd edition (ADOS-2).

The research involved 43 school-age children divided into two groups:

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The study highlights the importance of identifying transdiagnostic domains that overlap between ADHD and ASD. The transdiagnostic domain refers to a set of symptoms or behaviors that are common across multiple diagnostic categories rather than being specific to just one. Identifying these domains in mental health practice and in psychological research is crucial to understanding, properly diagnosing, and treating conditions with overlapping features. This understanding could pave the way for tailored treatments addressing the specific needs of children with ADHD, particularly those exhibiting autistic-like symptoms.

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Recent research by Brancati et al. reviews the efficacy and safety of non-stimulant medications for adult ADHD. Atomoxetine, a well-studied non-stimulant, has shown significant effectiveness in treating ADHD symptoms in adults. The review highlights the importance of considering dosage, treatment duration, safety, and the presence of psychiatric comorbidities when prescribing atomoxetine.

Additionally, certain antidepressants, including tricyclic compounds, bupropion, and viloxazine, which possess noradrenergic or dopaminergic properties, have demonstrated efficacy in managing adult ADHD. Antihypertensive medications, especially guanfacine, have also been found effective. Other medications like memantine, metadoxine, and mood stabilizers show promise, whereas treatments like galantamine, antipsychotics, and cannabinoids have not yielded positive results.

The expert opinion section of the review emphasizes that while clinical guidelines primarily recommend atomoxetine as a second-line treatment, several other non-stimulant options can be utilized to tailor treatments based on individual patient needs and comorbid conditions. Despite these advancements, the authors call for further research to develop and refine more personalized treatment strategies for adults with ADHD.

This review underscores the growing landscape of non-stimulant treatment options, offering hope for more personalized and effective management of ADHD in adults.

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