Men addicted to internet porn site may develop an inability to be turned on by real partners, two new studies say. According to at least two recent studies, "More and more young Italian men are suffering from 'sexual anorexia' and are unable to get erections because of Internet porn use that started in their mid-teens." Marnia Robinson, author of "Cupid's Poisoned Arrow," said a growing number of otherwise healthy young men who were, however, Internet porn addicts developed an inability to be turned on by real partners. "Desperate young men from various cultures, with different levels of education, religiosity, attitudes, values, diets, marijuana use, and personalities are seeking help. They have only two things in common: heavy use of today's Internet porn and increasing need for more extreme material," she said in an article posted on Psychology Today. Most men are astonished to learn that pornography use can be a source of sexual performance problems, she said. "They are amazed that heavy porn use can affect them adversely, that no one told them it could affect them, and that humans have actually masturbated without porn. There is almost total ignorance about the significance for porn users of the recent discoveries of addiction science," she said. Robinson said many have previously been to doctors, undergone various tests, and been declared "just fine" physically. The final diagnosis was generally "performance anxiety." Robinson said the cause appears to be physiological, not psychological. "It's all free, easy to access, available within seconds, 24 hours a day, 7 days a week. Overstimulation of the reward circuitry in the brain is a very real possibility today," she added. Quitting can be quite challenging due to an alarming temporary drop in libido, and some men experience withdrawal symptoms. These include insomnia, irritability, panic, despair, concentration problems, and even flu-like symptoms. Robinson said the brain needs a chance to "reboot," or return to normal dopamine sensitivity A survey of 28,000 users found that many Italian males started an "excessive consumption" of porn sites as early as 14 and after daily use in their early to mid-20s became inured to "even the most violent" images, said Carlo Foresta, head of the Italian Society of Andrology and Sexual Medicine (SIAMS). After developing their sexuality largely divorced from real-life relationships, Foresta said, the effects were gradual but devastating.