Porn and The Brain
You don't inject or inhale porn. It's not a drug, so it can't hurt your brain like one.
Heard that one before? Turns out it's a myth.
1. When researchers compared brain scans of porn users with scans of nonusers, they found that the more porn the person had used, the less his reward center activated when porn images were flashed on a screen. The researchers said, “This is in line with the hypothesis that intense exposure of pornographic stimuli results in a downregulation of the natural neural response to sexual stimuli.”
2. With a dulled reward center, a person can’t feel dopamine’s effects as well as they used to. As a result, the porn a person is using can stop producing the same excitement it did before. This leads many users to go in search of more hard-core material to get a bigger dopamine burst.
3. People with Internet addiction have been found to have less gray matter in several important areas of the brain, including the frontal lobes (which oversee things such as planning, prioritizing, and controlling impulses), the striatum (which is involved with the reward center and with self-control), and the insula (an area involved with feeling empathy and compassion for others). The vast majority of people with porn addictions have Internet addictions.
4. One study showed that even moderate porn use correlated with having reduced gray matter. Though it did not conclusively show that porn had caused the reduction, the study led researchers to conclude that porn use was the most likely explanation. They even subtitled their study “The Brain on Porn”. The study also found a correction between the length of time spent watching porn and the amount of gray matter reduction in the brain’s reward circuitry, which is important in motivation and decision-making. This reduction is also indicative of having a numbed pleasure response. The researchers interpreted the reduction as an effect of porn use.
5. Addiction researchers have found that brain problems seen in Internet addicts, similar to the problems seen among porn users, improved with abstinence and treatment, indicating that the addiction was the problem, not a preexisting condition.
6. Almost every study on addiction has demonstrated atrophy of multiple areas of the brain, particularly those associated with frontal volitional control and reward salience centers. This is true for addictions to drugs such as cocaine, methamphetamine, and opioids, and also for behavioral conditions associated with pathologic overconsumption of food, sex, and the Internet.
7. The journal NeuroImage published a study in 2008 demonstrating that as men are sexually aroused by pornography, the mirror neurons in the brain also fire. This means that the brain naturally imagines the porn viewer in the scene. The man is not merely responding to the naked woman. His brain is mirroring the pornographic scene with the viewer as the main character, heightening arousal.
8. When a person continually strengthens the brain maps linking sexual excitement to porn, those maps enlarge and can crowd out maps linking sexual excitement to a real person or to real sex.
9. In 2005, Dr. Eric Nestler wrote a landmark paper describing addiction as a dysfunction of the reward centers of the brain. Addiction occurs, he explained, when pleasure-reward pathways are hijacked by certain euphoria-inducing activities, such as eating, taking drugs, or having sex. 
1 Simone Kühn and Jürgen Gallinat, “Brain Structure and Functional Connectivity Associated with Pornography Consumption: The Brain on Porn”, JAMA Psychiatry 71, no. 7 ( July 2014), doi:10.1001/jamapsychiatry.2014.93.
3 Daniel H. Angres and Kathy Bettinardi-Angres, “The Disease of Addiction: Origins, Treatment, and Recovery”, Disease-a- Month 54, no. 10 (October 2008), doi:10.1016/j.disamonth.2008.07.002.
4 Matthias Brand, Kimberly S. Young, and Christian Laier, “Prefrontal Control and Internet Addiction: A Theoretical Model and Review of Neuropsychological and Neuroimaging Findings”, Frontiers in Human Neuroscience 8 (May 27, 2014), doi:10.3389/fnhum.2014.00375.
5 Kühn and Gallinat, “Brain Structure”.
6 Tian-Min Zhu et al., “Effects of Electroacupuncture Combined Psycho-Intervention on Cognitive Function and Event-Related Potentials P300 and Mismatch Negativity in Patients with Internet Addiction”, Chinese Journal of Integrative Medicine 18, no. 2 (February 2012), doi:10.1007/s11655-012- 0990- 5.
7 Teresa R. Franklin et al., “Decreased Gray Matter Concentration in the Insular, Orbitofrontal, Cingulate, and Temporal Cortices of Cocaine Patients”, Biological Psychiatry 51, no. 2 ( January 15, 2002), doi:10.1016/s0006-3223( 01)01269-0.
8 Paul M. Thompson et al., “Structural Abnormalities in the Brains of Human Subjects Who Use Methamphetamine”, Journal of Neuroscience 24, no. 26 ( June 30, 2004), doi:10.1523/jneurosci.0713-04.2004.
9 Kyoon Lyoo et al., “Prefrontal and Temporal Gray Matter Density Decreases in Opiate Dependence”, Psychopharmacology 184, no. 2 (December 21, 2005), doi:10.1007/s00213-005- 0198- x.
10 Nicola Pannacciulli et al., “Brain Abnormalities in Human Obesity: A Voxel-Based Morphometry Study”, NeuroImage 31, no. 4 ( July 15, 2006), doi:10.1016/j.neuroimage.2006.01.047.
11 Boris Schiffer et al., “Structural Brain Abnormalities in the Frontostriatal System and Cerebellum in Pedophilia”, Journal of Psychiatric Research 41, no. 9 (2007), doi:10.1016/j.jpsychires.2006.06.003.
12 Kai Yuan et al., “Internet Addiction: Neuroimaging Findings”,Communicative and Integrative Biology 4, no. 6 (November 1, 2011), doi:10.4161/cib.17871.
13 H. Mouras et al., “Activation of Mirror-Neuron System by Erotic Video Clips Predicts Degree of Induced Erection: An FMRI Study”, NeuroImage 42, no. 3 (September 1, 2008), doi:10.1016/j.neuroimage.2008.05.051.
14 Norman Doidge, The Brain That Changes Itself: Stories of Personal Triumph from the Frontiers of Brain Science (New York: Viking, 2007).
15 Clark Watts and Donald L. Hilton, “Pornography Addiction: A Neuroscience Perspective”, Surgical Neurology International 2, no. 1 (February 2011), doi:10.4103/2152-7806.76977.