When I see gee-whiz news reports about science, even in very reputable publications like The Economist, I think to turn to Peter Norvig's article "Warning Signs in Experimental Design and Interpretation"
There is an interesting comment in the Discover post, where Carl Zimmer (author of popular science book on parasites) points out several studies from all around the world (Jamaica, China, Indonesia, Philippines) where they found children got smarter after de-worming:
http://blogs.discovermagazine.com/notrocketscience/2010/06/2...