It’s a common and erroneous belief that addiction equals “harm” to the brain, or that addiction is caused by “damage” to the brain. While certain addictive substances (meth, alcohol) can be neurotoxic, addiction is caused by a specific constellation of brain changes that are not necessarily classified as “brain damage”. Debunking the damage as addiction meme, nicotine (delivered via cigarettes) is considered by some to be the most addictive substance, yet nicotine is a brain enhancer and has other possible health benefits (“most addictive” means that a greater percentage of users eventually become addicts). See articles about nicotine’s possible benefits: Nicotine: An Unlikely Brain Enhancing Drug.
Addiction is primarily a disorder of learning & memory – in that many (but not all) addiction-caused brain changes employ the same mechanisms as involved in learning and memory: Addiction as a Learning Disorder. That said, brain changes such as desensitization or hypofrontality may involve changes not strictly under the umbrella of learning (loss of grey matter, lowered metabolism, decreased functional connectivity).
Addiction researchers agree that those who develop behavioral addictions experience brain changes similar to those with drug addictions. This doesn’t mean that every single cellular and biochemical alteration is exactly the same in everyone with an addiction. Instead, it means that all addictions share a few key brain abnormalities. Four major brain changes are involved with both drug and behavioral addictions, as outlined in this paper published this year in The New England Journal of Medicine: “Neurobiologic Advances from the Brain Disease Model of Addiction (2016)“. This landmark review by the Director of the National Institute on Alcohol Abuse and Alcoholism (NIAAA) George F. Koob, and the director of the National Institute on Drug Abuse (NIDA) Nora D. Volkow, not only outlines the brain changes involved in addiction, it also suggests in its opening paragraph that sex addiction exists:
“We conclude that neuroscience continues to support the brain disease model of addiction. Neuroscience research in this area not only offers new opportunities for the prevention and treatment of substance addictions and related behavioral addictions (e.g., to food, sex, and gambling)….”
In simple, and very broad, terms the major fundamental addiction-caused brain changes are: 1) Sensitization, 2) Desensitization, 3) Dysfunctional prefrontal circuits (hypofrontality), 4) Dysfunctional stress circuits. All 4 of these brain changes have been identified among the 50 neuroscience-based studies on frequent porn users & sex addicts:
- Sensitization (cue-reactivity & cravings): Brain circuits involved in motivation and reward seeking become hyper-sensitive to memories or cues related to the addictive behavior. This results in increased “wanting” or craving while liking or pleasure diminishes. For example, cues, such as turning on the computer, seeing a pop-up, or being alone, trigger intense hard to ignore cravings for porn. Some describe a sensitized porn response as ‘entering a tunnel that has only one escape: porn’. Maybe you feel a rush, rapid heartbeat, even trembling, and all you can think about is logging onto your favorite tube site. Studies reporting sensitization or cue-reactivity in porn users: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25.
- Desensitization (decreased reward sensitivity): This involves long-term chemical and structural changes that leave the individual less sensitive to pleasure. Desensitization often manifests as tolerance, which is the need for a higher dose or greater stimulation to achieve the same response. Some porn users spend more time online, prolonging sessions through edging, watching when not masturbating, or searching for the perfect video to end with. Desensitization can also take the form of escalating to new genres, sometimes harder and stranger, or even disturbing. Remember: shock, surprise or anxiety can jack up dopamine. Some studies use the term “habituation,” which may involve learning mechanisms or addiction mechanisms. Studies reporting desensitization or habituation in porn users/sex addicts: 1, 2, 3, 4, 5, 6, 7, 8.
- Dysfunctional prefrontal circuits (weakened willpower + hyper-reactivity to cues): Alterations in prefrontal functioning and connections between the reward circuit and the frontal lobe lead to reduced impulse control, yet greater cravings to use. Dysfunctional prefrontal circuits show up as the feeling that two parts of your brain are engaged in a tug-of-war. The sensitized addiction pathways are screaming ‘Yes!’ while your ‘higher brain’ is saying, ‘No, not again!’ While the executive-control portions of your brain are in a weakened condition the addiction pathways usually win. Studies reporting “hypofrontality” or altered prefrontal activity in porn users: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17.
- Dysfunctional stress circuits – which can result in even minor stress leading to cravings and relapse because it activates powerful sensitized pathways. Studies reporting dysfunctional stress responses in porn users/ sex addicts: 1, 2, 3, 4, 5.
Are these the only brain changes? No. Each of these broad-brush indicators reflects multiple subtler addiction-related cellular and chemical alterations—just as the scan of a cancer tumor wouldn’t show associated subtler cellular/chemical changes. Most of the subtler changes can’t be assessed in human models due to the invasiveness of the technologies required. However, they have been identified in animal models (see this March, 2018 op-ed by the head of NIDA, Nora D. Volkow What Does It Mean When We Call Addiction a Brain Disorder?).
Sensitization is believed to be the core brain change, as it makes you crave it, whatever “it” is, and involves nearly the same mechanisms as early sexual conditioning. Watch – Adolescent Brain Meets Highspeed Internet Porn (2013), which is about sexual conditioning via internet porn during adolescence. In fact, the Cambridge university brain scan study (and 20 others in this list) found sensitization (greater cue reactivity or cravings) in compulsive porn users.
That said, each drug uniquely affects physiology, and drugs may alter the brain in ways that behavioral addictions do not. In addition, drugs such as cocaine and meth raise dopamine far higher (at first) than levels attainable with natural rewards. It’s quite possible that drugs, due to their toxicity, can cause permanent damage to dopamine systems, which behavioral addictions do not.
That’s why it’s incorrect when websites or speakers state that Internet porn is just like meth or crack cocaine. Such analogies lead people to think that that porn use can cause damage just like meth use. For some, kicking porn addiction may be harder than kicking drug addiction, but this does not indicate it causes greater neurological damage. The difficulty in ending an addiction may simply correlate with the level of neuroplastic change caused by use.
Even more annoying are those who say that behavioral addictions cannot exist, or that they are “compulsions,” but not true addictions. Such statements have no scientific basis, since the same molecular switch triggers both behavioral and chemical addictions. The master switch that triggers addiction-related changes is the protein DeltaFosB. High levels of consumption of natural rewards (sex, sugar, high-fat) or chronic administration of virtually any drug of abuse cause DeltaFosB to accumulate in the reward center.
Addiction neuroplasticity can be summarized as: continued consumption → DeltaFosB → activation of genes → changes in synapses → sensitization and desensitization. (See The Addicted Brain for more detail.) It appears that addiction-related brain changes eventually lead to loss of executive control (hypofrontality) and an altered stress response, other major features of addiction.
DeltaFosB’s evolutionary purpose is to motivate us to “get it while the getting is good!” It’s a binge mechanism for food and reproduction, which worked well in other times and environments. These days it makes addictions to junk food and Internet porn as easy as 1-2-3.
Note that addictive drugs only cause addiction because they magnify or inhibit mechanisms already in place for natural rewards. This is why the American Society of Addiction Medicine unambiguously states that food and sex addictions are true addictions.
Sensitization of addiction pathways is one brain change that may persist in both drug and behavioral addictions. In simple terms, these pathways represent strong memories, which when triggered, crank up the reward circuitry, and thus cravings.
Will sensitization fade over time? Eric Nestler thinks so. He does a lot of research on the brain mechanisms of addiction. Here’s a Q&A from his website. He has particularly studied DeltaFosB, the protein and transcription factor (meaning it controls the activation of genes) mentioned above.
09. Can the changes in your brain be reversed?
A. “There is no evidence that changes in the brain associated with drug addiction are permanent. Rather, we believe that these changes can be reversed, although this can take a long time, often many years and the reversal requires “unlearning” many of the bad habits (compulsions) associated with addiction.”
But the changes do generally linger for some unknown amount of time. It’s clear that DeltaFosB accumulates during above-normal levels of eating and sexual activity. We wonder if the positive changes that recovering porn users generally see at about 4-8 weeks may be related to declines in DeltaFosB.
From an article called “The Pleasure Principle” in Science magazine:
Nestler and his colleagues have found at least one molecule that appears to be specific for addiction, however. The protein, called [DELTA]-FosB, builds up in the reward pathway after repeated exposure to drugs and sticks around longer than other proteins–for as long as 4 to 6 weeks after the last dose. The protein increases an animal’s sensitivity to drugs and can also induce relapse if injected.
DeltaFosB also builds up in mice addicted to wheel running (a behavioral addiction closer to compulsive porn use).
The question is, “Does the accumulation of DeltaFosB cause changes in the genes—which hang around much longer than does DeltaFosB itself? Even ‘forever’ in some brains? If so, do these genetic changes occur primarily with drugs and not with exaggerated natural rewards like Internet porn?
Many serious drug addicts recover and eventually live life without cravings. However, if those same addicts were administered their drug of choice in circumstances they associate with its use, how many would binge, or perhaps become a practicing addict again? Who knows?
Clearly, addicts sometimes relapse after periods of abstinence. One opinion is that their brains are permanently sensitized (by DeltaFosB) to react to the addiction, and exposure reactivates these old pathways. Under this model, the brain has been permanently altered, but “damage” may be too strong a word. A former porn addict may be sensitized (likely to relapse) to porn or related cues and may need to stay away from porn. Indefinitely. But would you say his brain is damaged? No.
The following excerpt is from one of Nestler’s papers, and he suggests that DeltaFosB might someday be used as a bio-marker for the level of addiction and recovery.
If this hypothesis is correct, it raises the interesting possibility that levels of ΔFosB in nucleus accumbens or perhaps other brain regions could be used as a biomarker to assess the state of activation of an individual’s reward circuitry, as well as the degree to which an individual is ‘addicted’, both during the development of an addiction and its gradual waning during extended withdrawal or treatment. The use of ΔFosB as a marker of a state of addiction has been demonstrated in animal models. Adolescent animals show much greater induction of ΔFosB compared with older animals, consistent with their greater vulnerability for addiction.
Note that adolescents show much greater accumulation of DeltaFosB. (They also produce higher levels of dopamine.) Starting Internet porn at age 11-12 is perhaps a worst case scenario for our limbic brains.
Also see Why are cravings (a rush) still triggered after rebooting?
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