January 16, 2024
Infants begin to transition from breast or formula milk to solid food at about six months of age, as they gradually develop interest in food and the ability to chew.
The American Academy of Pediatrics recommends breastfeeding for the first six months. The European Society of Pediatric Gastroenterology Hepatology and Nutrition recommends initiation of supplementary food around that time. The World Health Organization (WHO) has set a 2025 goal of getting most mothers worldwide to breastfeed exclusively through the first six months of infancy.
Noting that “inconsistent findings have been reported in previous national survey-based studies,” a South Korean study team conducted a nationwide population study to explore the relationship between breastfeeding and subsequent rates of ADHD.
South Korea has a mandatory single-payer national health insurance system – the National Health Insurance Service (NHIS) – that covers virtually the entire population. Detailed and consistent NHIS records facilitate nationwide population studies.
One NHIS program is the National Health Screening Program for Infants and Children (NHSPIC), which includes periodic examinations by trained pediatricians up to six years of age.
Using these national records, the team identified a cohort of over 1.1 million infants. These same records show that a little over a third (36%) received nothing but formula milk feeding during their first six months. About a fifth (21%) received a mix of formula and breast feeding. Almost a half (43%) were exclusively breastfed.
ADHD diagnoses were made by physicians during hospital visits.
The team adjusted for a series of confounders that were found to influence outcomes: sex, year of examination, residence, socioeconomic status, preterm birth, birth weight, and body measurements (weight, microcephaly) at examination (4–6 months of age).
With these adjustments, partial breastfeeding was associated with a small but significant (9%) reduction in the odds of infants later being diagnosed with ADHD, relative to infants receiving only formula milk feeding.
Exclusive breastfeeding was associated with a much larger 23% reduction in the odds of infants later being diagnosed with ADHD, relative to exclusive formula feeding.
What’s especially noteworthy is the dose-response pattern that suggests that breastfeeding may have a protective effect.
A separate analysis comparing infants who began transitioning to supplementary solid food before versus after six months found absolutely no difference in the odds of subsequently being diagnosed with ADHD.
A similar pattern emerged for autism spectrum disorder on all counts, again reflecting a dose-response pattern, pointing to what may be a broader beneficial effect of breastfeeding for healthy neurologic development.
The team concluded, “The risk of ADHD and ASD [autism spectrum disorder] considerably decreased with breastfeeding, and this tendency was more prominent in children who received EBF [exclusive breastfeeding] than in those who received PBF [partial breastfeeding]. Our study strengthens and supports the idea that breastfeeding is beneficial in preventing NDDs [neurodevelopmental disorders] in children. We suggest that breastfeeding be encouraged and recommended to promote good neurodevelopmental outcomes.”
Jong Ho Cha, Yongil Cho, Jin-Hwa Moon, Juncheol Lee, Jae Yoon Na, and Yong Joo Kim, “Feeding practice during infancy is associated with attention-deficit/ hyperactivity disorder and autism spectrum disorder: a population-based study in South Korea,” European Journal of Pediatrics (2023), https://doi.org/10.1007/s00431-023-05022-z.
Background:
Our understanding of Attention-deficit/hyperactivity disorder (ADHD) has grown and evolved considerably since it first appeared in the DSM-II as “Hyperkinetic Reaction of Childhood.” This study aimed to find the disorder’s placement within the modern psychopathology classification systems like the Hierarchical Taxonomy Of Psychopathology (HiTOP).
The HiTOP model aims to address limitations of traditional classification systems for mental illness, such as the DSM-5 and ICD-10, by organizing psychopathology according to evidence from research on observable patterns of mental health problems.. Is ADHD best categorized under externalizing conditions, neurodevelopmental disorders, or something else entirely? A recent study by Zheyue Peng, Kasey Stanton, Beatriz Dominguez-Alvarez, and Ashley L. Watts takes a closer look at this question using a symptom-focused approach.
The Study:
Traditionally, ADHD has been associated with externalizing behaviors, such as impulsivity and hyperactivity, or with neurodevelopmental traits, like cognitive delays. However, this study challenges the idea of placing ADHD into a single category. Instead, it maps ADHD symptoms across three major psychopathology spectra: externalizing, neurodevelopmental, and internalizing.
The findings reveal that ADHD symptoms don’t fit neatly into one box. For example, symptoms like impulsivity, poor school performance, and low perseverance were strongly associated with externalizing behaviors. On the other hand, cognitive disengagement (e.g., daydreaming, blank staring) and immaturity were closely linked to neurodevelopmental challenges. Interestingly, cognitive disengagement also showed ties to internalizing symptoms, such as anxiety or depression.
This research underscores the complexity of ADHD. Rather than treating ADHD as a single, unitary construct, the study advocates for a symptom-based approach to better understand and treat individuals. By acknowledging that ADHD symptoms relate to multiple psychopathology spectra, clinicians and researchers can move toward more nuanced classification systems and targeted interventions.
Conclusion:
Ultimately, this study highlights the need for modern systems to move beyond rigid categories and adopt a more flexible, symptom-focused framework for understanding ADHD’s place in psychopathology.
The Background:
Caffeine and its primary breakdown compounds – paraxanthine, theophylline, and theobromine (also the primary alkaloid in chocolate) – readily cross the placenta and tend to linger due to the underdevelopment of fetal caffeine metabolizing enzymes.
Could accumulating caffeine metabolites harm the developing fetal brain? Studies to date have come to contradictory conclusions, some finding an association, others finding none.
Norway has a national single-payer health insurance system with a national health registry comprehensively tracking virtually all residents.
The Methods:
An international study team used Norways’s registry, and its Mother, Father, and Child Cohort Study (MoBa) to explore the relationship between maternal and paternal coffee consumption and offspring neurodevelopmental difficulties (ND), including symptoms of ADHD as determined from validated rating scales, using 58,964 mother-child pairs and 22,576 father-child pairs, covering the decade 1999-2008.
Unadjusted results indicated a strong association between maternal coffee consumption before and during pregnancy with offspring ADHD, but none with paternal coffee consumption. Superficially, that might seem like compelling evidence.
Yet after adjusting for education, income, smoking, and alcohol, “previously significant effects attenuated towards zero and some associations switched from being positive to negative.”
Then, after further adjusting for genetic confounding, ADHD symptoms at 1.5 years, 3 years, 5 years (on both of two different rating scales), and 8 years (including separate measures of inattention and hyperactivity symptoms) all became indistinguishable between offspring from mothers consuming coffee during pregnancy and offspring of mothers abstaining from coffee during pregnancy.
Conclusion:
The team concluded, “This study applied several conventional and genetic epidemiological approaches to investigate the potential relationship between maternal coffee consumption during pregnancy and offspring NDs [neurodevelopmental difficulties]. When considering the results of the conventional and genetic epidemiological analyses, as well as the broader literature, we conclude that there is little evidence that maternal coffee consumption during pregnancy is strongly causally related to offspring NDs.”
More specifically, the team found no evidence of any causal relationship with offspring ADHD.
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.”
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