A study from the University of Bergen announced on June 26 shows an association between exclusive breastfeeding up to six months of age and a reduced risk of attention-deficit/hyperactivity disorder (ADHD) symptoms in children from ages three to eight.
Researchers examined data from 37,600 families participating in the Norwegian Mother, Father and Child Cohort Study. Mothers provided information through a questionnaire six months after birth regarding the duration of exclusive breastfeeding, partial breastfeeding, and when other foods or liquids were introduced. This information was used to calculate how long each child was exclusively breastfed.
"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. The association appeared in both boys and girls and was strongest at ages three and five. All forms of breastfeeding showed some effect on lowering ADHD symptoms, but the effect increased with longer duration and intensity, with exclusive breastfeeding up to six months showing the strongest association.
The study also considered genetic factors associated with ADHD. Researchers noted that mothers with ADHD symptoms tend to breastfeed less than others and are more likely to have children who show signs of ADHD. Additionally, children exhibiting early ADHD symptoms may be more difficult for mothers to breastfeed. "This may partly explain the relationship between lower breastfeeding and increased ADHD symptoms in children," said Solberg.
To address possible confounding factors, researchers adjusted for known genetic risks for ADHD as well as sociodemographic variables. Sibling analyses compared different patterns within families. "Even after these adjustments, there was a clear but moderate protective effect of the duration of exclusive breastfeeding on later ADHD symptoms," Solberg explained.
Solberg cautioned that participants in this cohort tend to have higher education levels than average Norwegians and are more likely both to breastfeed at all and for longer durations than is typical nationally. She said it is possible that "the effect could be even greater in groups where breastfeeding is less common." However, she emphasized caution about drawing firm conclusions: "As with other observational studies, it is difficult to draw firm conclusions about causality." Solberg added that while heredity remains a strong risk factor for developing ADHD in society today, their findings suggest environmental factors such as extent of breastfeeding may also play a role.
