Meg Meeker, MD, on Teenagers and the STD nobody is talking about: Most people are aware of the physical repercussions of sex–we e now have 35 known STDs (in 1960, we only had two); teenagers make up one-third of the U.S. population, but they carry 50 percent of STDs; one in four teens has an STD. (Over 80% of those infections have no symptoms, so they can go undetected, which is dangerous for the teen, their future sexual partners and their future children.) You may be familiar with those numbers, but few are aware of the emotional repercussions teen sex can have. For the thousands of teens I’ve treated and counseled, many of them—yes, teen boys too—have depression related to sexual activity. You rarely hear the correlation made, but I consider depression an STD with effects as devastating as HPV, chlamydia or any physical infection.