Not interested in sex? Perhaps you have a condition called hypoactive sexual desire disorder, caused by a brain chemical imbalance. That’s the message conveyed in a new “educational campaign” launched last week by the Society of Women’s Health Research with actress Lisa Rinna as a celebrity spokesperson talking about “the brain’s potential role in desire.” On the campaign’s new website, you might conclude that if you’re not fantasizing about sex a lot you should definitely talk to your doctor.