Sex addiction is a recurring theme in movie plots and TV series, in the real lives of movie and TV actors, even in discussions about whether this politician or that one may suffer from some form of the disorder. All of this presupposes that sex addiction is real. But experts are at odds about whether it is actually a medical phenomenon they can diagnose and treat in their patients.

“I will unequivocally say that sex addiction does not exist,” sex therapist and licensed marriage and family therapist Ian Kerner, Ph.D., author of She Comes First, tells SELF. “There was a big attempt by the addictionology community to get sex addiction into the most recent version of the Diagnostic and Statistical Manual, [released in 2013], under the category of hypersexuality,” he adds. “It was rejected by the American Psychological Association for lack of enough research and empirical data.”

On the other hand, the 2017 version of the International Classification of Diseases, compiled by the World Health Organization, includes excessive sexual desire and nymphomania under “Other sexual dysfunction not due to a substance or known physiological condition.”

In Kerner’s corner is the American Academy of Sexuality Educators, Counselors, and Therapists, which in December 2016 released a statement emphasizing their belief that sex addiction isn’t real. “[AASECT] does not find sufficient empirical evidence to support the classification of sex addiction or porn addiction as a mental health disorder and does not find the sexual addiction training, treatment methods, and educational pedagogies to be adequately informed by accurate human sexuality knowledge,” the statement reads in part.

Michael Aaron, Ph.D., a sex therapist in New York City and author of Modern Sexuality, helped write that statement. “Sex addiction is this nebulous umbrella term, and it’s problematic,” he tells SELF.

The fundamental problem is that experts can't nail down a definition for what "sex addiction" really is, and therefore disagree on whether it is even a diagnosable disorder.

According to the American Society of Addiction Medicine, “Addiction is a primary, chronic disease of brain reward, motivation, memory, and related circuitry. Dysfunction in these circuits leads to characteristic biological, psychological, social, and spiritual manifestations….Without treatment or engagement in recovery activities, addiction is progressive and can result in disability or premature death.”

When you’re addicted to something, you pursue it “pathologically,” ASAM notes. “Impulsivity turns to compulsivity, you have an inability to stop, and there’s preoccupation: You can only think about the thing itself,” certified sex therapist and certified sex addiction therapist and supervisor Alexandra Katehakis, Ph.D.(c), M.F.T., clinical director of the Center for Healthy Sex, tells SELF. As someone who believes in sex addiction but is an AASECT-certified sex therapist, she can see both sides of the debate, she says.

“Certainly, sex can become out of control. But when you use the word ‘addiction,’ you’re using a comparison to the way the brain is affected by drugs and alcohol,” Kerner says.

While some experts say sex doesn't lead to comparable neurological effects, many sex addiction therapists disagree. “With drugs and alcohol, an external substance alters the neurochemistry of the body. With things like compulsive sex, internal mechanisms are creating neurobiological and neurochemical [changes],” Katehakis says.

That’s fundamentally true, as seen during the normal sexual response cycle. When you’re excited, physiological changes, like the release of the neurotransmitter dopamine, abound. According to Katehakis, people can get hooked on the rush, whether that’s due to sex or drugs: “[These actions] form deeper neural pathways as they become habituated. Humans have very malleable brains, so these become adaptive patterns.”