Babies who are breastfed for longer in their first six months may be less likely to show signs of ADHD as they grow up, according to a study published in the journal Biological Psychiatry. The research team from the University of Bergen, Norway, found a clear link between how long a child was exclusively breastfed and lower levels of ADHD symptoms between the ages of three and eight.
Why Breast Milk Matters
Breast milk is the main source of food for newborns, specifically designed by nature for each child and is packed with ingredients that help babies grow and their brains develop. These include long-chain fatty acids, amino acids, protective antibodies, and helpful bacteria, all things that play important roles in a child’s early development.
Because of this, scientists have long been curious about how breastfeeding might shape brain development and the immune system in babies. That curiosity is what led the team at Bergen to look more closely at the connection between breastfeeding and ADHD.
“It is well established that psychiatric symptoms and disorders can be influenced by both genetic and environmental factors,” said Berit Skretting Solberg, psychiatrist and researcher at the Department of Biomedicine, University of Bergen, and senior consultant at Betanien Hospital.
What the Researchers Did
The team looked at data from 37,600 families taking part in the Norwegian Mother, Father and Child Cohort Study (known as MoBa). Six months after giving birth, mothers filled out a questionnaire describing how they fed their babies, including whether they breastfed exclusively, did a mix of breast and formula, or introduced other foods and liquids early on.
Using this information, the researchers calculated how many months each child had been exclusively breastfed. They then tracked the kids over time, checking for signs of ADHD at ages three, five, and eight.
What They Found
The results were striking. Children who had been exclusively breastfed for longer (up to six months) showed fewer ADHD symptoms as they got older. “We found that the longer a child was exclusively breastfed (up to six months), the lower the level of ADHD symptoms at ages three, five, and eight years,” said Solberg.
This pattern showed up in both boys and girls. The effect was strongest at ages three and five and slightly weaker by age eight. Any breastfeeding seemed to help, but the benefit grew with how much and how long mothers breastfed, with exclusive breastfeeding for six months showing the strongest effect.
Sorting Out the Genetic Piece
ADHD has a strong genetic component, which makes this kind of research tricky. For instance, mothers with ADHD themselves tend to breastfeed less and are more likely to have children with ADHD. On top of that, babies who already show signs of ADHD can be harder to breastfeed in the first place. “This may partly explain the relationship between lower breastfeeding and increased ADHD symptoms in children,” said Solberg.
To untangle these factors, the researchers adjusted their data to account for known genetic risk of ADHD and family background. They also compared siblings within the same family who had been breastfed differently, as a way to control for shared genes and environment. However, “even after these adjustments, there was a clear but moderate protective effect of the duration of exclusive breastfeeding on later ADHD symptoms,” Solberg explained.
A Few Things to Keep in Mind
Solberg is careful to point out that the MoBa study doesn’t perfectly reflect the wider population. The families who take part tend to be more highly educated and more likely to breastfeed for longer than average. Interestingly, that means the effect could be even bigger in groups where breastfeeding is less common.
As with any observational study, it’s hard to say for certain that breastfeeding directly causes the lower ADHD risk, it’s only possible to say that the two are linked. More research will be needed to fully understand what’s going on. Still, the findings hint that genetics aren’t the whole story when it comes to ADHD.
“In our society, heredity is likely the strongest risk factor for ADHD. However, since ADHD—like other neurodevelopmental disorders—is influenced by multiple factors, our study suggests that the extent of breastfeeding may also help protect against the development of ADHD symptoms in young children.”
Solberg BS, Brantsæter AL, Kvalvik LG, Hartman CA, Xie T, Klungsøyr K, Li L, Larsson H, Gjestad R, Haavik J. Breastfeeding and Development of Attention-Deficit/Hyperactivity Disorder Symptoms Across Childhood. Biol Psychiatry. 2026 Jun 19:S0006-3223(26)01348-X. doi: 10.1016/j.biopsych.2026.06.009