Here’s some headline news for anyone who has been trained that Internet porn use is harmless: Physical evidence of addiction processes is showing up in the brains of avid Internet video-gamers. What’s more, use of online erotica has greater potential for becoming compulsive than online gaming according to Dutch researchers.

According to NIDA head Nora Volkow, MD, and her team these three physical changes define addiction: desensitization (numbing of the brain’s pleasure response), sensitization, and hypofrontality. These same brain changes (which are now showing up in Internet addicts) also show up in pathological gamblers and drug abusers.

For example, cocaine use floods the brain’s reward circuitry with dopamine. Nerve cells respond, more or less quickly, by decreasing their responsiveness to dopamine. As a result, some users feel “off” (desensitization). They crave more intense stimulation (tolerance), and tend to neglect interests, stimuli, and behaviors that were once important to them.

At the same time, because their brains have recorded that cocaine use feels good, they grow hypersensitive to anything they associate with cocaine. White powder, the word “snow,” the neighborhood where they smoked, or friends with whom they used will all trigger spurts of high dopamine in the reward circuitry, driving them to use (sensitization). Also, ΔFosB, a protein that helps preserve intense memories and promotes relapse, accumulates in key brain regions. Incidentally, ΔFosB also rises with sexual activity.

If heavy cocaine use continues, the desensitization of the reward circuitry decreases corresponding activity in the frontal lobes of their brains. Now, the users’ abilities to control impulses and make sound choices weaken, and their frontal cortex may atrophy (hypofrontality). Taken together, decreased pleasure response, marked cravings to use, and compromised impulse control fuel the vicious cycle of addiction.

Behavioral addictions

The study of non-drug addictions is still quite new. Yet already experts have uncovered decisive physical evidence that today’s extreme versions of natural rewards can change the brain in ways that drugs do. “Natural rewards” are activities/substances that entice us because they enhanced our ancestors’ survival, or the survival of their genes.

Moreover, it’s not just a tiny minority with pre-existing disorders who are at risk. Normal, healthy brains can also change. Said a healthy 37-year old, “When I first watched porn online at age 35, I felt like I was going to have an orgasm without an erection. That’s how powerful an effect the it had on me.”

So far, here’s the research scorecard. (Dates indicate when brain-scan research turned up evidence of the last of the three key addiction-related brain changes.)

Pathological gambling – studied for 10 years, and added to the upcoming DSM-5 as an addiction (2010)

Food addiction – (2010)

Internet video-gaming addiction – (2011)

Internet porn addiction – still not studied via brain scans

Incidentally, the reason the Internet addiction studies address addiction to gaming, not porn, is that they were done in countries that block access to porn sites—and have for years (China, 2006 and Korea, 2007). Unlike other countries, they don’t have a lot of heavy porn users.

Here are studies showing the three critical, physical changes in the brains of Internet addicts (two just released in June, 2011):

Numbed pleasure response: Reduced Striatal Dopamine D2 Receptors in People With Internet Addiction (2011)

A reduction of striatal D2 dopamine receptors is the main marker for desensitization of the reward circuitry, a hallmark of all addictions. In this study PET scans of men with and without Internet addiction were compared.

“An increasing amount of research has suggested that Internet addiction is associated with abnormalities in the dopaminergic brain system… [In this study] individuals with Internet addiction showed reduced levels of dopamine D2 receptor availability.”

In this study, college students played Internet video games for 6 weeks. Measures were done before and after. Those subjects with the highest cravings also had the most changes in their brains that indicate early addiction process. The control group, which played a less stimulating game, had no such brain changes.

“These changes in frontal-lobe activity with extended video-game play may be similar to those observed during the early stages of addiction.”

In this study, researchers found a 10-20% reduction in frontal cortex gray matter in adolescents with Internet addiction. Research on other addictions has already established that decreases in frontal-lobe gray matter and functioning reduce both impulse control and the ability to foresee consequences.

“The presence of relatively immature cognitive control, makes [adolescence] a time of vulnerability and adjustment, and may lead to a higher incidence of affective disorders and addiction among adolescents. As one of the common mental health problems amongst Chinese adolescents, internet addiction disorder (IAD) is currently becoming more and more serious. … The incidence rate of internet addiction among Chinese urban youths is about 14%. … These results demonstrated that as internet addiction persisted, brain atrophy … was more serious.” (Also see this earlier Chinese study.)



Online porn and video gaming stimulate the brain in comparable ways

Compare these two quotations. Which is about porn addiction and which is about gaming addiction?

We don’t have sex anymore. We don’t go on date nights or anything together. I feel so guilty because I just can’t take it anymore. Ever since 2 weeks into our marriage I was threatening to divorce him.

Three of my friends did realize they had a problem, but 2 of them said they’ve made attempts to quit, and they literally think there’s nothing they can do about it. *

The characteristics that make Internet porn and video gaming so popular are the same characteristics that give both the power to dysregulate dopamine in some brains. Novelty and ‘stimuli that violate expectations‘ both release dopamine, sending the brain the message that the activity is more valuable than it is. Successful video games deliver a rapid-fire of both novelty and surprise. Each new generation of games exceeds the last in these respects.

Today’s porn also delivers both, and constantly ratchets them up. There’s unending novelty and something more startling always beckoning just beyond the next click. There’s also the dopamine released by the “hunt” for the perfect shot. Novelty, shock and hunting absorb the user’s attention because they raise dopamine levels. Intense focus allows users to override their natural satiety mechanisms and, often, to rewire their brains in ways that take a lot of effort to undo. Addiction is “pathological learning.”

Online gamers are sometimes called “adrenaline junkies.” However, adrenaline (which is released in the adrenal glands) appears to have little effect on addiction processes. Dopamine, not adrenaline, is at the heart of all addictions. Fear and anxiety can enhance addiction processes due to neurochemicals released in the brain (such as norepinephrine), but they don’t cause those processes.

Sexual cues can be more compelling than gaming activities

Mock warfare and risky quests were no doubt high priorities for our ancestors. That’s why we find play rewarding enough to get hooked. Yet reproduction is our genes’ top priority. Like food, sex is essential to genetic success.

In terms of effects on the brain, Internet porn use combines elements of consuming highly palatable food and video gaming’s constant stimulation. Like junk food, Internet erotica is a hyperstimulating version of something we evolved to value highly. Today’s erotica is also delivered via a rapid-fire, mesmerizing medium, very similar to online video games. A double whammy in terms of addictiveness.

It’s worth considering what brain researchers have learned about food. When rats had unlimited access to cafeteria food, nearly all of them showed a rapid drop in D2 (dopamine) receptors (numbed pleasure response), and then binged to obesity. The D2-receptor drop apparently motivates mammals to grab as much as possible while the getting is good—whether high-calorie foods or a willing harem.

Keep in mind that unlimited cafeteria-type food stimulation was not the norm during our evolution, until recently. That’s why unlimited access to junk food is risky to rats and humans. Clicking effortlessly to hundreds of hot, novel mates is also an evolutionary anomaly, and 9 out of 10 of college-age men were already using Internet porn three years ago. Risky, given its inherent addictiveness. Also, reversible. When heavy users give up porn, they report increased pleasure from all aspects of life (often after a miserable withdrawal).

Back to food. In recent years, brain researchers have also turned up evidence of all three key addiction processes in the brains of overeaters:

Numbed pleasure response: A 2010 study showed that overeating blunts the reward circuitry, increasing the risk for future weight gain. After 6 months, the brains of those who had eaten more “pleasurable” foods (i.e., more fattening) showed less response to pleasure than the others.

A 2010 study showed that overeating blunts the reward circuitry, increasing the risk for future weight gain. After 6 months, the brains of those who had eaten more “pleasurable” foods (i.e., more fattening) showed less response to pleasure than the others. Sensitization: A 2011 study found that those who score high on a food addiction test (brain activation in response to pictures of food) show brain responses similar to drug addicts’ responses to drugs.

A 2011 study found that those who score high on a food addiction test (brain activation in response to pictures of food) show brain responses similar to drug addicts’ responses to drugs. Hypofrontality: A 2006 study revealed that obese individuals have brain abnormalities in areas associated with taste, self-control, and reward—including a reduction of gray matter in the frontal lobes (atrophy). It’s likely that overeating causes these changes, as the study mentioned above confirmed brains changes from overeating.

If overstimulation via highly palatable food can cause brain changes in so many humans (30% of Americans are obese, and only about 10% due to metabolic abnormalities according to neuroscientist David Linden), how is it possible that over-stimulation via highly erotic online sexual activity could not change brains? Internet porn use/cybersex is surely no less stimulating than tempting food.

Is history repeating itself?

History is full of examples of “common knowledge” that turned out to be erroneous upon investigation. Consider margarine. Everyone “knew” it was better for you than butter. Experts were so confident of this “fact,” that they didn’t even test it for years, and regularly advised people to substitute margarine for butter.

Finally, experts did test the healthfulness of margarine. It turns out that trans-fatty acids (found in margarine) are among the most dangerous fats. They are far worse for humans than butter.

Critics may claim that it is “unscientific” to suggest that Internet porn can cause addiction processes in the brain just because Internet addiction clearly does. Actually, it’s unscientific to suggest the reverse. All addictions, including behavioral ones (gambling, food, video games) show hypofrontality (atrophy and lack of impulse control). Frankly, what critics now need to supply is solid, scientific evidence showing that Internet porn addiction is an exception to the rule. To suggest there’s still major doubt about its addictiveness is most unscientific, as it presumes there must be some other brain circuitry for porn use that has yet to be discovered.

Sex is healthy, but the assumption that Internet porn use is safe is increasingly tenuous.





* The first remarks are about gaming addiction, the second about porn addiction.