To my complete lack of surprise (though not the researchers'), a survey of over 400 Scottish pensioners (senior citizens) found no association between measured intelligence (these people were part of a group given an intelligence test at 11) and current level of happiness. While intelligence may accrue you certain material benefits, it may also lead to more dissatisfaction.

Preliminary results from the first study of the effect of fish oil on preschoolers indicate dramatic improvement in the performance of underachieving (often disruptive and inattentive) preschoolers.