Reliable figures for the number of diagnosed sex addicts are difficult to come by, but the Society for the Advancement of Sexual Health, an education and sex-addiction treatment organization, estimates that between 3 and 5 percent of the U.S. population—or more than 9 million people—could meet the criteria for addiction. Some 1,500 sex therapists treating compulsive behavior are practicing today, up from fewer than 100 a decade ago, say several researchers and clinicians, while dozens of rehabilitation centers now advertise treatment programs, up from just five or six in the same period. The demographics are changing, too. “Where it used to be 40- to 50-year-old men seeking treatment, now there are more females, adolescents, and senior citizens,” says Tami VerHelst, vice president of the International Institute for Trauma and Addiction Professionals. “Grandfathers getting caught with porn on their computers by grandkids, and grandkids sexting at 12.”…

Although sex addicts sometimes describe behavior akin to obsessive-compulsive disorder, research hasn’t directly correlated the two. But a growing body of research shows how hypersexual disorder can fit into other forms of addiction. At the Promises treatment centers, clinicians have observed a number of sex addicts who have relapsed with drugs or alcohol in order to medicate the shame they felt. Severe depression can also follow after an addict starts to confront the condition. “I realized I was not comfortable in my own skin,” says Valerie, who checked herself into four months of treatment for sex addiction at Del Amo, a private behavioral-health hospital in Torrance, Calif. “My depression came from the fear I was going to be alone for the rest of my life. Fighting the obsession and rumination, the fear of loneliness and abandonment.”

Sex addicts are compelled by the same heightened emotional arousal that can drive alcoholics or drug addicts to act so recklessly, say addiction experts. Research shows that substance abusers and sex addicts alike form a dependency on the brain’s pleasure-center neurotransmitter, dopamine. “It’s all about chasing that emotional high: losing yourself in image after image, prostitute after prostitute, affair after affair,” says the Sexual Recovery Institute’s Weiss. “They end up losing relationships, getting diseases, and losing jobs.”