Breastfeeding duration is associated with improved cognitive scores at ages 5 through 14, even after controlling for socioeconomic position and maternal cognitive ability, according to a new study published this week in PLOS ONE by Reneé Pereyra-Elías, Maria Quigley and Claire Carson of the University of Oxford, U.K.

Previous studies have found an association between breastfeeding and standardized intelligence test scores; however, a causal relationship is still debated.

Improved cognitive outcomes could potentially be explained by other characteristics—such as socioeconomics and maternal intelligence—of the women who breastfeed their babies.