Celebrity sex addicts who race off to the nearest rehab clinic after scandal breaks may hope to cull sympathy for their "disease," but scientists now say that hypersexuality looks notably different from drug addiction, at least in the brain.
Try telling that to "Californication" actor David Duchovny, golf pro Tiger Woods or TV star Charlie Sheen, who have all acknowledged being addicted to their sexual proclivities in one way or another.
Or disgraced former Rep. Anthony Weiner, who, in the battle to be mayor of New York City, is fighting off previously undisclosed reports of sexting women while saying that his problematic behavior is "behind" him.
For the past decade or so, addiction has been a catch-all term associated with people who say their sexual urges are out of control. But a new study examines whether hypersexuality is a medical condition with neurological markers.
Hypersexuality, it turns out, might be more akin to impulse-control disorders like kleptomania or gambling. And the model scientists are using for treating so-called sex addictions as a disease might be all wrong, doctors and clinicians say.
For the first time, researchers at UCLA have measured brain waves in people who say they have trouble regulating their viewing of pornography. They found no evidence that the brain lights up in the same way it does in drug addicts.
The preliminary study "challenges the basic notion of what we believed and thought," said study co-author Dr. Timothy Fong, associate professor of psychiatry at the Semel Institute for Neuroscience and Human Behavior at UCLA and director of its impulse control disorders clinic.
But, he cautioned, "We cannot jump to the conclusion that sex addiction is not real. Instead, we need to understand more about the relationship between sexual desire and sexual behavior."
Researchers looked at data gathered on 52 adults -- 13 women and 39 men -- who had reported repetitive sexual activity that was problematic in their lives. They then used electroencephalography, or EEG, to measure responses in the part of the brain that controls reward and emotional response.
Participants were shown a variety of positive and negative images: dismembered bodies, people preparing food and people skiing. They were also shown images of sex, some romantic and others of explicit intercourse.
The hypothesis was that the brain images would look like previous studies done on people addicted to chemicals like cocaine and alcohol.
When cocaine addicts are exposed to images of the drug, their brains become hyperactive and "light up," Fong said. The worse the addiction, the more activity was seen in the middle brain.
"The surprising part is their brains didn't light up on fire," he said of the sex addicts. "We thought we would see a difference and we didn't.
"In order to define a disease, you have to come up with clear differences between normal functions and when the brain is not functioning normally and then you identify the symptoms," Fong added.
"Instead of platitudes, we are coming up with actual science that might give us a target for treatment."
Data for the study was collected by assistant professor Nicole Prause while she was teaching at another university and then analyzed by her UCLA peers. It appeared in the online edition of the journal Socioaffective Neuroscience and Psychology.
Fong does not deny that sufferers have a "true disease," but it might be that "addiction" is the wrong diagnosis.
"The lines get blurred with personality and culture and treatment," he said. "I hope this is a call to action for researchers, community advocates and families. We need to learn more about the relationship between physiology and sexual behavior and to come up with a way to engage in healthier sex."
Psychiatrists like Fong want to know whether there are "biological origins" of hypersexuality in the brain: "Why does it happen in some people and not in others?"
"If you think about why sex is so different than alcohol or cocaine, is that it is part of a basic function in life, it's like eating," Fong said. "But at the same time, we are creating a culture of sex that is entertainment."
About 4 to 6 percent of the population struggles with some kind of hypersexuality, Fong said.
The term sex addict has been so ubiquitous that magazines like Marie Claire have run lists of the "most famous" sex addicts, starting with President John F. Kennedy and including men like comedian Russell Brand, as well as television's Dr. Drew alumni Amber Smith and Kendra Jade Rossi.
In the case of Weiner, he was reportedly treated for three days at a psychiatric clinic in Houston after his resignation from Congress in 2011.
But he told New York's Daily News, "It wasn't an addiction thing -- it was just a place to get away and to meet people -- who might be able to help," he said.
Researchers and those in the clinical world have been at odds for years over what exactly constitutes hypersexuality and if it is, indeed, a true addiction.
The diagnosis of hypersexuality failed to make this year's DSM-5, the latest version of the Diagnostic and Statistical Manual of Mental Disorders.
But field studies in 2012 showed that the five criteria used to describe a hypersexuality diagnosis are reliable: "excessive time" consumed by sexual fantasies, planning or engaging in sex; repetitive engagement in response to anxiety, depression, boredom or irritability; repetitive engagement in response to stresses; inability to control urges and behaviors; engaging in sexual behaviors while disregarding risk for harm to self or others.
Rory C. Reid, assistant professor of psychiatry at UCLA, said this latest research comes from a "theoretical model" and does not take into account years of clinical experience.
Reid was not part of the study, but he addresses its limitations in a critique that has been widely circulated among psychiatrists.
"I know patients who come in and say they lost their job because they could not stop looking at porn at work, even though human resources gave them three warnings," Reid told ABCNews.com. "They've had serial extramarital affairs and anonymous unprotected sex and have chlamydia. Their marriages are coming apart and they feel unable to stop themselves.
"They don't care what we call it: 'Call it chicken pox, but help me.' This is a legitimate problem, and it's wreaking havoc in their lives."
That, he said, is why the study is controversial, because it "attacks the explanation for why they have this. ... We should be able to look at the brain and find pathology if it's a disease."
And perhaps rehab therapists are using the wrong model to treat those seeking help for hypersexual behavior. "What the study says is maybe a disease model isn't a good fit to explain this problem," he said.
Reid and Fong say more research needs to be done to help the medical community understand how to help these people.
"The bigger question that the study brings up is what is an addiction?" Reid said. "Answering that question is a Pandora's box waiting to happen. We have been debating it for years. Why haven't we figured this out after we have spent millions?
"There are two camps. One is the scientist -- who suggests it's a pathology and a true disorder you can see. And the other community are sex addiction therapists who say, 'Well, it looks like a duck and smells like a duck, it's probably a duck."
But Reid said it may be a completely different animal.
"We need a better explanation," he said. "And if there is a better theory, we need to understand it so we can go after it, because it will mean better treatment."