Unfortunate that you're being down-voted for being skeptical, this study does have some issues confounding the results:

"The elevated BLL intervention package includes treatments previously demonstrated to impact later-life outcomes such as: visits from health workers; increased medical care; nutritional assessments and dietary modifications; and referral to the Special Supplemental, Nutrition Program for Women, Infants, and Children (WIC). Prior research documents long-term benefits from programs similar to each of these elements ..."