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April 30, 2024
This study investigates how certain genetic disorders, called RASopathies, affect the structure of the brain in children. RASopathies are conditions caused by mutations in a specific signaling pathway in the body. Two common RASopathies are Noonan syndrome (NS) and neurofibromatosis type 1 (NF1), both of which are linked to a higher risk of autism spectrum disorder (ASD) and attention deficit and hyperactivity disorder (ADHD).
The researchers analyzed brain scans of children with RASopathies (91 participants) and compared them to typically developing children (74 participants). They focused on three aspects of brain structure: surface area (SA), cortical thickness (CT), and subcortical volumes.
The results showed that children with RASopathies had both similarities and differences in their brain structure compared to typically developing children. They had increased SA in certain areas of the brain, like the precentral gyrus, but decreased SA in other regions, such as the occipital regions. Additionally, they had thinner CT in the precentral gyrus. However, the effects on subcortical volumes varied between the two RASopathies: children with NS had decreased volumes in certain structures like the striatum and thalamus, while children with NF1 had increased volumes in areas like the hippocampus, amygdala, and thalamus.
Overall, this study highlights how RASopathies can impact the development of the brain in children. The shared effects on SA and CT suggest a common influence of RASopathies on brain development, which could be important for developing targeted treatments in the future.
In summary, understanding how these genetic disorders affect the brain's structure can help researchers and healthcare professionals develop better treatments for affected children.
McGhee CA, Honari H, Siqueiros-Sanchez M, Serur Y, van Staalduinen EK, Stevenson D, Bruno JL, Raman MM, Green T. RASopathies influences on neuroanatomical variation in children. Biol Psychiatry Cogn Neurosci Neuroimaging. 2024 Apr 13:S2451-9022(24)00103-4. doi: 10.1016/j.bpsc.2024.04.003. Epub ahead of print. PMID: 38621478.
Refractive errors, such as myopia (nearsightedness), hyperopia (farsightedness), and astigmatism (distorted vision due to irregular curvature of the eye or lens), are common worldwide. These conditions affect 12%, 5%, and 15% of children, and rise significantly in adults to 26.5%, 31%, and 40%. Additionally, strabismus (misalignment of the eyes) and amblyopia (reduced vision in one eye from uneven image formation, often linked to strabismus) occur globally at rates of 2% and 1.4%, respectively.
Visual impairment can affect children’s concentration in school, and studies suggest a link between eye disorders and ADHD.
To investigate this relationship, two researchers – one based in the US and the other in Israel –carried out a nationwide retrospective cohort study using electronic medical records of all insured individuals aged 5 to 30 who were part of Maccabi Health Services, Israel’s second largest health maintenance organization, between 2010 and 2022.
Of over 1.6 million insured members (2010–2020), inclusion/exclusion criteria and propensity score matching for age and sex were applied, along with a one-year wash-out period between the first eye diagnosis and ADHD diagnosis. In total, 221,707 cases were matched with controls without eye disorders at a 1:2 ratio, resulting in a cohort of 665,121 participants.
Overall, those with any previous eye diagnosis were 40% more likely to have a subsequent ADHD diagnosis. This was slightly higher for females (45%) than for males (35%). It was also slightly higher for children and adolescents (42%) than for adults (37%).
More specifically:
The authors concluded that eye disorders are associated with ADHD. They noted these associations were more marked in females and children and adolescents, although, as noted above, those differences were small. They recommended that primary care providers and neurologists consider risk stratification for early screening, and that ophthalmologists refer high-risk patients for ADHD evaluation.
Acid-suppressive medications, including proton pump inhibitors (PPIs) and histamine-2 (H2) receptor antagonists, are often prescribed during pregnancy to treat heartburn and gastroesophageal reflux disease.
Research shows changes in the gut microbiome can negatively affect neurodevelopment. Since acid-suppressive medications alter gut microbiota, maternal use during pregnancy may impact offspring’s neurodevelopment. Because PPIs and H2 receptor antagonists readily cross the placental barrier, they could potentially influence fetal neurodevelopment.
The link between prenatal exposure to acid-suppressive medications and major neuropsychiatric disorders is not well understood. With the use of these medications during pregnancy rising, it is important to assess their impact on children's long-term neurodevelopment. This study examined whether maternal use of acid-suppressive drugs is associated with increased risk of neuropsychiatric disorders in children, using a large, nationwide birth cohort from South Korea.
South Korea operates a single-payer health insurance system, providing coverage for over 97% of its citizens. The National Health Insurance Service (NHIS) maintains a comprehensive database with sociodemographic details, medical diagnoses, procedures, prescriptions, health examinations, and vital statistics for all insured individuals.
A Korean research team analyzed data from over three million mother-child pairs (2010–2017) to assess the risks of prenatal exposure to acid-suppressing medications. They applied propensity scoring to adjust for maternal age, number of children, medical history, and outpatient visits before pregnancy, to minimize confounding factors. That narrowed the cohort to just over 800,000 pairs, with half in the exposed group.
With these adjustments, prenatal exposure to acid-suppressing medications was associated with 14% greater likelihood of being subsequently diagnosed with ADHD.
Yet, when 151,737 exposed births were compared to the same number of sibling controls, no association was found between prenatal exposure and subsequent ADHD, which suggests unaccounted familial and genetic factors influenced the preceding results.
The Take-Away:
Evidence of these medications negatively affecting pregnancies is mixed, mostly observational, and generally reassuring when these medications are used appropriately. Untreated GERD and gastritis, however, have known risks and associations with the development of various cancers. With no evidence of an association with ADHD (or for that matter any other neuropsychiatric disorder), there is no current evidence-based reason for expectant mothers to discontinue use of acid-suppressing medications.
For years, a persistent concern has shadowed the treatment of Attention-Deficit/Hyperactivity Disorder (ADHD): Does the medication eventually stop working? Patients often report that their symptoms seem to return despite consistent use, leading to "dose escalation" or "medication holidays." A new systematic review from Sam Cortese’s team published in CNS Drugs finally puts these concerns to the test by synthesizing decades of empirical research.
Before diving into the findings, you must understand two often-confused phenomena:
The review analyzed 17 studies covering over 10,000 individuals, and the results provide a much-needed reality check for the clinical community.
The researchers found preliminary evidence that acute tolerance (tachyphylaxis) can occur within a 24-hour window.
The most important finding is that tolerance does not commonly develop to the therapeutic effects of ADHD medication in the long term. In one landmark study following children for up to 10 years, only 2.7% of participants lost their response to methylphenidate without a clear external explanation. Doses, when adjusted for natural body growth, remained remarkably stable over years of treatment.
Consistent with the lack of therapeutic tolerance, the body does not become tolerant to the physical side effects of stimulants. Increases in heart rate and blood pressure typically persist for as long as the medication is taken. This underscores why clinicians must continue monitoring cardiovascular health throughout the entire duration of treatment.
If it’s Not Tolerance, What Is It?
If "tolerance" isn't real, why do some patients feel their medication is failing? The review suggests clinicians look at these alternative explanations:
Why This Matters
These results provide clinicians the confidence to tell patients that their medication is unlikely to "wear out" permanently. Rather than immediately increasing a dose when symptoms flare, the first step should be a "clinical deep dive" into the patient's lifestyle, stress levels, and adherence.
For researchers, the review highlights a major gap: most existing studies are small, dated, or of low quality. There is a dire need for robust, longitudinal studies that track both the brain's response and the patient's environment over several years.
For people with ADHD, while your body might get "used to" the initial "buzz" of a stimulant within hours, its ability to help you focus and manage your life remains remarkably durable over the years.
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