Today, with pornography only ever a few clicks away, a multitude of attitudes to sex imagery abound. Regardless of what porn aficionados have to say, Swedish researchers maintain that excessive porn consumption affects the brain.

Like every other gratifying experience, watching sexual images releases high levels of the neurotransmitter dopamine, which is often referred to as the "happiness drug" and is a key ingredient in the brain's reward system. It is known to create vivid memories and spur a strong desire to relive the same stimulation again.

Neuroscientist Predrag Petrovic, an associate professor of psychiatry at the Karolinska Institute, Stockholm, has long studied the brain's reward system and maintains that high consumption of pornography affects the brain in a similar way to other habits.

"This is the very purpose of the reward system. So it is no surprise if some images get stuck, especially when it concerns such strong instincts as sex and reproduction. Pornography is also widespread to such an extent today, that it may no longer be regarded as a 'natural' stimulus," Predrag Petrovic said, as quoted by the Swedish daily Dagens Nyheter.

Petrovic is more inclined to use the term "abuse" when talking about viewing porn, when it starts to forgo other activities one would like to do instead.

"Excessive consumption almost always leads to an altered brain, no matter what you are doing. However, pornography does not create a [physical] dependency in the same way as drug abuse because no external substances are involved," Predrag Petrovic noted.

A 2014 study by the Max Planck Institute showed that men who watched a lot of porn had a smaller amount of gray matter in a specific area of the frontal lobe, which is activated when people try to control their behavior. According to Petrovic, it is debatable whether this is a matter of a cause-or-effect.

"Actually, the causation could be reversed here, in that some people consume more porn since they had a poor ability to control impulses from the offset," Petrovic said.

Niklas Långström, a professor of child and adolescent psychiatry at the Karolinska Institute, who specializes in the treatment of sex offenders and various types of aggressive behavior, concurred that existing studies are so methodologically flawed that it makes it virtually impossible to draw causational conclusions, comparing it to the chicken-or-the-egg problem.

Although it is difficult to establish a direct connection between pornography and a penchant for violence, which is often maintained, porn consumption nevertheless seems to affect end users' sexual habits and preferences. For instance, a 2016 survey by an international team of researchers including Niklas Långström found porn consumers to make sexual debuts earlier, have more sexual partners and casual relations. Additionally, there are testimonies from women who admittedly feel pressured into certain types of sexual positions commonly seen in porn films.

However, the contrary view can also be argued. Sexual experience makes consumers seek out a certain type of pornography. Porn surfing was found to be powered by a thrill that researchers maintained was particularly common among young people who have not managed to acquire many sexual experiences of their own.

Indeed, getting to the bottom of how excessive porn surfing alters the brain is difficult, let alone being able to prove it with experimental studies.