Another study, another outcome that makes you say, "Duh!"
I couldn't find the article referenced on WSJ.com so here's what that chaps at Joystiq had to say about it:
Game companies are worried about gamers growing up and growing bored said the Wall Street Journal earlier this week (available only through subscription). A study of "lapsed console gamers" by consulting and research firm Frank N. Magid Associates shows where gamers lose the faith. The first drop occurs as males enter the 18-34 demo, where those playing console games once a week drops from 78 percent (12-17 year-olds) to 42 percent. At 35-44 the playing drops to 24 percent.