Here is the article that ran last week: http://www.psmag.com/navigation/books-and-culture/horrible-consequences-reading-banned-books-78715/#.U2tjKJfmv2U.twitter. A study of Texas teens "found no connection between reading edgy books and mental health issues or delinquent behavior." Indeed, the converse was true with these kids: they were more likely to be involved in as volunteers in their community.
The concluding paragraph contains a sentiment I have often shared with others when discussing banned books and whether readers should be permitted to read books with edgy or dark content: “Consuming edgy material … may provide teachable moments to discuss ethical issues between parents and children...Banning such material may be counterproductive in removing these teachable opportunities.”"
I recall many discussions with the former residents of the back bedroom based on books they were reading. The did provide wonderful parenting moments. Some of the books I shared with my middle school students provided plenty of teachable moments as well.
This study is small in scale and should be replicated, but it is a boon to be able to point to some research that addresses directly the concerns of many who challenge and seek to ban books.