Why does Anthony Weiner keep doing it?

The lewd behavior that New York mayoral candidate Anthony Weiner engaged in suggests he is struggling with more than bad behavior and could be dealing with a variety of issues driving his problematic sexual behavior, experts said.

But doctors, clinical psychologists and sex therapists differ on the role of biology, as well as issues such as anxiety, depression and insecurity.

Fred Berlin, director of the Sexual Behaviors Consultation Unit at Johns Hopkins Hospital, said many of his patients exhibit behavior similar to Weiner’s, although he and other experts cautioned that they could not speak to the former congressman’s specific situation.

“It’s driven behavior,” said Berlin, a psychiatrist who has been treating patients for more than 30 years. “People are feeling they are pushed to act a certain way even though their intellect and their conscience may be telling them otherwise.”

Berlin said he has treated patients with problematic sexual behavior from all backgrounds and levels of society. People with this type of behavior are energized by a powerful biological force, he said. Other factors, such as anxiety or depression, may play a role.

“But fundamentally, there is a driver there that they are not resisting for whatever reason,” he said. “It really is about sex.”

He likened it to someone who is going on a diet to lose weight. That person may be convinced they want to stop overeating when they’re not hungry, he said. But when they get hungry, they may not be able to stop themselves and end up gorging. The person is genuinely sorry afterward, he said, and then the cycle repeats.

In 2011, Weiner resigned from Congress after he admitted to sending lewd pictures of himself to young women. On Tuesday, he acknowledged that under the pseudonym “Carlos Danger,” he again sent graphically explicit texts and images to young women more than a year after stepping down from political life.

Berlin and others said that in the past five to six years, they have seen a significant increase in the number of patients with problematic sexual behavior related to the Internet, including inappropriate chatting, accessing inappropriate images and engaging in virtual relationships.

In addition to making it easier for people to say and do things they might not otherwise, the Internet has become a delivery system through which someone can get access to an unlimited number of partners and sexual fantasies, said Michael Radkowsky, a District of Columbia psychologist who treats couples and individuals with sexual issues. The human brain is wired to look for sex and sexual partners, he said.

“Our brains have all these receptors looking for sex, and there’s the Internet providing all sorts of opportunities for sex. Wham, plugs right in.”

Experts disagree on whether this type of behavior should be considered an addiction.

The American Psychiatric Association considered including “hypersexual disorder” in its most recent edition of the guidebook that psychiatrists and other mental health clinicians use to diagnose mental disorders.

Among the symptoms associated with that behavior, according to preliminary criteria, are recurrent and intense sexual fantasies, sexual urges or sexual behaviors over a period of at least six months that interfere with other important activities; are in response to stressful life events; or are undertaken while disregarding risk for physical or emotional harm to self and others.

The issue sparked huge controversy, experts said, and ultimately, the behavior was not included in the updated Diagnostic and Statistical Manual of Mental Disorders, or DSM-5.

David Kupfer, chair of the DSM-5 task force, said the disorder may interfere with a person’s life, “but the empirical evidence on the condition was not strong enough to support including it in DSM at this time.”

A recent study from the University of California at Los Angeles questioned the validity of sex being addictive. Past research has shown that when addicts view pictures of their drug of choice, their brain activity spikes. Psychiatrist Nicole Prause thought she might see the same type of response in possible sex addicts when viewing images of people having sex -- but she didn’t.

Rather than an addiction, hypersexuality could mean possessing a high libido coupled with other factors such as impulsivity, said Prause.

Whatever it’s called, experts also disagree on other issues involved in the behavior.

“With men like Anthony Weiner, it’s rarely about the sexual component. There are usually other issues, like grandiosity -- thinking that rules don’t apply -- or certain personality characteristics,” said Rachel Needle, a West Palm Beach, Fla. clinical psychologist and certified sex therapist of the American Association of Sexuality Educators, Counselors and Therapists.

To treat people like Weiner, one also needs to understand what role the sexual behavior is playing, she said. “What is it helping him with controlling anxiety? Or feeling not good about himself?”

Thinking that rules don’t apply to them is a common personality characteristic of people in power, not just in politics, but also in sports, she said, citing the problems of golf star Tiger Woods, who apologized for cheating on his wife in 2010 after weeks of tabloid reports of marital infidelity with as many as a dozen women.

Hani Miletski, a Bethesda, Md. sex therapist, agrees that other issues besides sex are often involved.

“It never happens in a vacuum. There are always other things going on,” she said.