A recent study has found that breastfeeding is linked to fewer behavioral problems in children. I stress linked because there’s no causative finding.
The findings suggest that, at least in term children, longer duration of breast feeding is associated with fewer parent-rated behavioural problems in children aged 5 years.
Among term children, for example, those who were breast-fed for at least four months had a 29% chance of having an abnormal “behavior score”, compared with 35% for those who had not been breast fed for that long. From the abstract, the study appears to have been observational, since it was based on interviews and questionnaires. Therefore any causative relationship (whether or not it exists) is not established by the study, since there could be many cofounders, such as religion or income.
What you can do.
Because there were no causative findings, probably the best thing you can do is find people who breastfeed and emulate their lives as closely as possible (I say this slightly tongue-in-cheek). Short of that, it’s hard to recommend much else.