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.