By Martha McLaughlin
The understanding that addiction is associated with changes in the brain was slow to come. For years, researchers were only able to examine brains after people had died, and they couldn’t see obvious differences between those who’d suffered from addiction and those who hadn’t.
Fortunately, research tools have improved considerably, and we now have a much greater understanding of how brain systems cause people to become consumed with a substance or behavior. But there’s still plenty to learn.
We know there are differences, for example, between the way that men and women are affected, and there are undoubtedly more gender-related variations to discover. It’s also not always clear which brain changes are a result of addiction and which drugs are a potential cause.
Pleasure and Pain
What we do know is that the human brain is designed so that behaviors that promote the survival of the species are pleasurable and people will want to repeat them. Activities such as eating, sex and social bonding cause an area of the brain called the ventral tegmental area to produce the neurotransmitter dopamine. Neurotransmitters are chemical messengers that affect the body by bonding to receptor cells, like keys fitting into locks.
When dopamine travels through the brain, it bonds to receptors in multiple areas, including one called the nucleus accumbens, which is associated with motivation and emotion. The dopamine surge causes feelings of pleasure and helps people learn to repeat whatever behavior caused it. The greater the surge, the stronger the association. The National Institute on Drug Abuse reports that drugs can release up to 10 times the normal amount of dopamine, and they note that it’s sometimes said, its for that reason, drug abuse is something people learn to do very, very well.1
The human body has ways to restore and maintain balance when it senses something is wrong, and when it’s flooded with too much dopamine, it reacts. It reduces the number of dopamine receptors or makes existing ones less sensitive. That’s why tolerance to a drug develops, causing people to need more of it over time.
It also explains why those suffering from addiction lose interest in other activities, which no longer produce the feelings of pleasure they once did. It appears that one of the reasons that some people are more prone to develop addiction to begin with is that they have a lower amount of a dopamine receptor called D2 than most people do.2
Addiction doesn’t just affect the parts of the brain associated with pleasure, but also parts associated with pain. Among other tasks, the brain region known as the anterior cingulate cortex (ACC) helps people regulate emotions and process conflict. The ACC is smaller and weaker in people dealing with addiction. One expert notes that because of the changes to the ACC, people suffering from addiction have a lowered ability to work through natural challenges and may begin to feel that pain is unsurmountable.3 This contributes to the vicious cycle of people turning to their drug of choice to cope when conflict arises.
Relapse and Recovery
One of the mysteries in addiction research has been what causes relapse in people who’ve appeared to be doing well. Researchers believe they’re closer to understanding a possible biological cause. Animal studies have demonstrated that there seems to be a period of time after drug use stops in which cravings for the drug diminish, but then they spike again, peaking after three months of abstinence.
The cravings appear to be associated with certain receptors in the nucleus accumbens which are missing a subunit, causing them to respond more strongly to drug use cues. When the researchers blocked the receptors, cravings lessened to almost normal levels.4
New addiction treatments are on the horizon, but even without them, the good news is that the brain can heal significantly. The shrinkage of the ACC, for example, is seen to reverse after people recover from addiction. The brain can also make new pathways, breaking old associations and rewiring itself to make new ones.
Addiction treatment can help people understand what to expect at various stages of the recovery process and give them the tools they need to combat cravings and manage negative emotions while the brain rebuilds. A brain that learns addiction can also learn how to escape the trap.
1 “Drugs, Brains, and Behavior: The Science of Addiction.” National Institute on Drug Abuse, Accessed April 13, 2018.
2 Ryback, Ralph. “Could You Be at Risk of Instant Addiction?” Psychology Today, August 18, 2015.
3 Gravagna, Nicole. “How Does Addiction Physically Change The Brain?” Forbes, August 22, 2017.
4 Piore, Adam. “Resetting the Addictive Brain.” Discover, April 2, 2015.