Addiction can develop when reward-seeking changes a teen's brain – Science News for Students

Teens often start using potentially addictive agents, such as alcohol and other drugs, at parties and other social events.
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February 10, 2022 at 6:30 am
It starts innocently enough. A friend offers you the latest e-cigarette sensation. Or maybe they hand you a beer or a hit of some other drug. You try it once. You enjoy the feeling and figure you’re done. For some people, this once is enough. But others may enjoy the experience enough to try it again. And again. After a while, the pleasure it once brought fades. Instead, a craving for the substance emerges. It starts to grow. The person now seeks out a hit — even when they don’t want truly want to.
This is addiction. And it’s a brain disease.
This disease makes it very difficult for someone to stop certain initially pleasurable behaviors. They might involve using nicotine, alcohol or other drugs, even drugs prescribed by a doctor. Gambling, shopping, gaming or social media use can also be addictive. Some people can even become addicted to food in a way that resembles drug abuse.
When someone engages in one of these pleasurable behaviors too often, the brain can change. Other brain networks now turn on a cycle of craving. Soon the behavior is no longer pleasurable. Instead, it is only an escape from the stress the addicted person feels when not doing the behavior.
Addiction often leads to physical and mental harm. For example, nicotine can reprogram parts of a teen’s brain. In some cases, addicting behavior can lead to serious health problems or even death. In others, people may sell off their belongings or abandon friends and family in their quest to satisfy their addiction.
Many addicted individuals claim they can quit at any time. But for someone with a true addiction, quitting that substance or behavior can be impossibly hard. It usually requires help from therapists, along with family, friends and other support groups. And engaging in the once pleasurable behavior later on can lead to a relapse — a seemingly unstoppable craving to do it again and again and again.
What causes casual use to become an addiction? Certain brain circuits create a cycle of craving. People with early-life stressors or a family history of addiction are at greater risk. So are people who start engaging in certain behaviors as adolescents. Even social and cultural pressures appear to play a role.
People who develop an addiction may spend a lifetime fighting it. The good news: Science shows you have control over your chances of becoming addicted.
Nicotine is the drug to which the most teens are exposed. It’s found in tobacco and many vaping products. People who smoke or vape will get a nicotine hit that stimulates their brains. It can give make them feel alert, relaxed or content. People who drink alcohol or use certain other drugs may feel a sense of euphoria — a pleasant intoxication.
That feel-good state is caused by dopamine, explains Dennis McChargue. He is an addiction researcher at the University of Nebraska–Lincoln. Dopamine is a chemical used by nerve cells to communicate with each other. Although the body uses different types of such neurotransmitters, dopamine is strongly linked to positive experiences.
When someone vapes or gets high on alcohol, marijuana or some other drug, their body releases dopamine. This chemical comes from the reward center of the brain, McChargue says. The nucleus accumbens (NU-klee-us Ah-KUM-bens) and dorsal striatum (DOR-sul Stry-AY-tum) are part of this reward center. They play a big role in how much we enjoy experiences. They also are responsible for forming habits. Indeed, scientists refer to addictive substances and behaviors as “habit-forming.”
Early on, the reward center will drive us to repeat a feel-good behavior. Dopamine “gives you a strong [feel-good] boost,” McChargue says. But it disappears pretty quickly, along with those good feelings. And that, he says, “makes you want to get that boost over and over again.”
As someone continues to seek out that boost, their brain starts to change. Neurons in the reward center begin to lose their dopamine receptors. This makes it harder for dopamine-using cells to chat with each other. What’s more, cells that produce dopamine now make less of it. So the dopamine rush keeps getting smaller. That pleasurable feeling is harder and harder to get.
At the same time, another brain region kicks into gear. Called the amygdala (Uh-MIG-duh-lah), it reacts to stress. This part of the brain makes people start to feel what’s known as withdrawal. Symptoms may include irritability, body aches and nausea. A person in withdrawal may feel sweaty and have trouble sleeping. They may struggle to concentrate on anything — except achieving that brain boost again. Only that next hit doesn’t provide the same pleasure. It only reduces the uncomfortable, stressful feelings caused by not having the reward.
Even after physical symptoms of withdrawal have passed, someone who is addicted often fixates on getting another hit or chance for a boost. This is caused by a third brain region. Sitting behind the forehead, the prefrontal cortex is in charge of executive function. That includes organizing thoughts and making decisions. It also includes prioritizing tasks. It even helps control emotions and impulses.
And at this stage of addiction, those thoughts and impulses become laser focused on getting another fix or reward.
Not everyone who uses nicotine or drugs or spends a lot of time shopping or on screens becomes addicted. But certain factors put some people at greater risk of this. One of those is genetics. People who face the most risk of addiction may have been born with one or more genes that make their response to pleasurable things especially rewarding.
“If you have addiction in your family,” McChargue says, “you might be more prone to the effects” of a habit-forming drug or other addictive behavior. Two people might drink the same amount of alcohol or take the same amount of some drug, he notes. Yet their experiences may differ. People with a family history of addiction are more likely to experience a stronger high.
The drug and its dose also can affect whether someone becomes addicted. Strong drugs, such as methamphetamine (Meth-am-FET-uh-meen), begin to change the brain after the very first use, McChargue says.
But just as important is how old someone is when they start using. “If you start earlier, the likelihood of becoming addicted later — in your late teens or twenties — is higher,” he says. Why? The adolescent brain is still developing.
“Even though [teens] look like adults, their brain is not at the adult level until their mid-twenties,” explains Lindsay Squeglia. She is a neuropsychologist at Medical University of South Carolina. This Charleston-based scientist studies how the brain and behaviors are related.
Different parts of the brain develop at different times, she notes. The reward center develops early. This underlies a teen’s impulsive behaviors. The prefrontal cortex acts as the brakes on such reward-driven behaviors. But this part of the brain isn’t mature until around age 25.
From early adolescence to early adulthood, the brain is under constant change. The body prunes back gray matter. These nerve cells are responsible for thoughts and emotions. “That’s totally normal,” Squeglia says. The brain keeps pathways that are regularly used and gets rid of ones that aren’t. These are “use-it-or-lose-it connections,” she explains.
At the same time, the amount of white matter in the brain increases. White matter is made up of neurons wrapped in layers of insulation. White matter makes up “the superhighways in the brain,” Squeglia says. Its insulation speeds up connections between distant brain areas and makes for faster messaging. Changes to both white and gray matter make the brain more efficient.
When teens start using substances such as nicotine, alcohol or other drugs, those normal brain changes become altered. Gray matter decreases faster than it does in non-users. White matter increases, but not as much. This disrupts the superhighway connections. The most impacted networks link the reward center and prefrontal cortex. That makes it even harder for the brain to cut back on rewarding activities. And this can lead to addictive behavior later, in adulthood.
“If kids start using alcohol before age 15, they are four times more likely [than those who start at age 20] to develop problematic alcohol use during their lifetime,” Squeglia says. “The earlier you start,” she notes, “the more problematic use [will be] down the road.”
Some brain changes last well into adulthood. This is especially true in people who start using substances as teens. Over time, Squeglia says, adults who struggle with substance abuse have less white matter and gray matter in their brains. One study found that people who used cannabis as teens but stopped as adults experienced mental-processing problems well into their forties. People who waited until they were adults to first use cannabis didn’t have the same problems.
“Delay,” Squeglia now urges. With each year teens put off using alcohol, the chances of becoming addicted go down by 14 percent, she says. Waiting to use other substances is similarly beneficial. That delay can have a huge impact on your future.
Many teens experiment with habit-forming substances because their friends or families do. But not every teen faces the same social pressures, notes Priscilla Lui. She is a clinical psychologist at Southern Methodist University in Dallas, Texas.
Friends and parents send messages that affect our behaviors, she says. “But often,” she adds, “we don’t really talk about where those messages come from.” Her research finds that culture — such as movies — can influence how teens think about nicotine and use of other drugs.
Lui studies the social and cultural influences on use of potentially habit-forming drugs. Addiction research hasn’t always matched her personal experiences and observations across cultures, she’s noticed. “The belief has been that people are people and cultural differences are just noise,” she says. But that’s why representation of diverse groups in science is so important, she says.
People use substances, particularly alcohol, for one of four main reasons, researchers found back in the 1990s. They want to cope with stress, to enhance their mood, to try to fit in or to socialize with others. Why someone uses addictive substances can affect their experiences. “People who drink to socialize are more likely to self-monitor and be responsible,” Lui says. They are more likely to stick with a friend and switch to water or eat food to avoid getting too drunk. They’re also less likely to leave a drink unattended. (This can be dangerous since someone can slip a drug into that drink.) In contrast, people who drink to fit in may not keep track of how much they consume. That can lead to serious illness and social problems.
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Even where someone grows up can matter. People living in lower-income areas are often inundated with ads for alcohol and cigarettes, Lui says. It can become the norm for people there to then use these substances. These neighborhoods are over-represented by people of color, and that puts them at a disadvantage. “By eighth grade, a lot of people have had exposure to alcohol and even cannabis,” Lui says. Teens who get an early start using substances can set themselves up for long-term problems.
“We need more information,” she says. Researchers need to study how social and cultural factors affect addiction-related behaviors. That will allow doctors to better tailor treatments. What works for one group may be less effective for another, she points out. There may be other risk factors, such as racism or income, that point to which treatment might work best in particular individuals.
Lui and Squeglia are both working to find better treatments, especially for teens with addiction. The motivators for using alcohol or other drugs are different for teens than for adults, Squeglia notes. So adult treatments may not work as well in kids. She’s working to find better ways to prevent the damaging long-term brain changes in teens who suffer from addiction.
The key is to get help early. “Putting a substance in your body makes you more vulnerable to experiencing negative emotions,” McChargue observes. That makes you more vulnerable to wanting to escape from those emotions — and leads you to want to use again. Every time you do this, those negative emotions increase, he says. That makes it harder to stop. That’s why, he says: “The earlier you can get treatment, the better.”
If someone you know has a substance- or behavioral-abuse problem, ask them to seek help. They can reach out to the Behavioral Health Treatment Services Locator (run by the U.S. Substance Abuse and Mental Health Services Administration), or to this hotline: 1-800-662-HELP (4357). And for teens trying to quit vaping, here are some free programs designed just for them.
ad: Short for advertisement. It may appear in any medium (print, online or broadcast) and has been prepared to sell someone on a product, idea or point of view.
addiction: The National Institute of Drug Abuse defines this as a complex chronic disease that is “characterized by drug seeking and use that is compulsive, or difficult to control, despite harmful consequences.” A first exposure to drugs is usually voluntary. But repeated use of certain drugs, NIDA explains, can create changes in the brain that make it hard “to resist intense urges to take drugs.”
addictive: (v. addicted) An adjective to describe something that become habit-forming in an uncontrolled or unhealthy way. This can include a drug or some habit (such as video game playing or phone texting). Such addictions reflect an illness triggered by brain changes that occur after using some drugs or engaging in some extremely pleasurable activities. People with an addiction will feel a compelling need to use a drug (which can be alcohol, the nicotine in tobacco, a prescription drug or an illegal chemical such as cocaine or heroin), even when the user knows that doing so risks severe health or legal consequences.
adolescence: A transitional stage of physical and psychological development that begins at the onset of puberty, typically between the ages of 11 and 13, and ends with adulthood. Someone in that transitional stage is known as an adolescent.
amygdala: An area deep within the brain and near the temporal lobe. Among other things, the amygdala plays a role in emotions. The term comes from the Greek word for an almond, which this region resembles in shape.
behavior: The way something, often a person or other organism, acts towards others, or conducts itself.
cell: (in biology) The smallest structural and functional unit of an organism. Typically too small to see with the unaided eye, it consists of a watery fluid surrounded by a membrane or wall. Depending on their size, animals are made of anywhere from thousands to trillions of cells.
chemical: A substance formed from two or more atoms that unite (bond) in a fixed proportion and structure. For example, water is a chemical made when two hydrogen atoms bond to one oxygen atom.
circuit: A network that transmits electrical signals. In the body, nerve cells create circuits that relay electrical signals to the brain. In electronics, wires typically route those signals to activate some mechanical, computational or other function.
clinical: (in medicine) A term that refers to diagnoses, treatments or experiments involving people.
cortex: The outermost part of an organ, such as the kidney or brain.
culture: (n. in social science) The sum total of typical behaviors and social practices of a related group of people (such as a tribe or nation). Their culture includes their beliefs, values and the symbols that they accept and/or use. Culture is passed on from generation to generation through learning. Scientists once thought culture to be exclusive to humans. Now they recognize some other animals show signs of culture as well, including dolphins and primates.
develop: (n. development) To emerge or to make come into being, either naturally or through human intervention, such as by manufacturing. (in biology) To grow as an organism from conception through adulthood, often undergoing changes in chemistry, size, mental maturity or sometimes even shape.
disrupt: (n. disruption) To break apart something; interrupt the normal operation of something; or to throw the normal organization (or order) of something into disorder.
dopamine: A neurotransmitter, this chemical helps transmit signals in the brain.
dorsal: The back of something, usually an animal.
euphoria: A sense of great joy, excitement, self-confidence and/or intense well-being.
executive function: The term that includes all of the brain functions needed for self-regulation, self-control and problem-solving. Executive function requires good working memory to hold several pieces of information in the brain at once. It also includes multi-tasking, prioritizing, reasoning, focus, concentration, goal setting and controlling impulses.
factor: Something that plays a role in a particular condition or event; a contributor.
gene: (adj. genetic) A segment of DNA that codes, or holds instructions, for a cell’s production of a protein. Offspring inherit genes from their parents. Genes influence how an organism looks and behaves.
gray matter: One of two main types of tissue found in the brain and spinal cord. It consists mainly of nerve cell bodies.
impulsive: (n. impulsivity) Quick to act; not willing to wait. Not waiting for deliberation or a weighing of consequences.
intoxicating: (n. intoxication) An adjective to describe something that can cause a sensory high (such as alcohol or certain other drugs) — or an event or condition that can also cause an extremely pleasurable sensation. The “drug” that does this is known as an intoxicant.
link: A connection between two people or things.
mature: (adj.) Connoting an adult individual or full-grown and fully developed (non-juvenile) form of something. (verb) To develop toward — or into — a more complex and full-grown form of something, be it a living thing, a technology or an idea.
media: A term for the ways information is delivered and shared within a society. It encompasses not only the traditional media — newspapers, magazines, radio and television — but also digital outlets, such as Twitter, Facebook, Instagram, TikTok and WhatsApp. The newer, digital media are sometimes referred to as social media. The singular form of this term is medium.
methamphetamine: A powerfully addictive drug. It is a neural stimulant, which means it makes people’s hearts beat faster and gives them more energy and focus. While most people use methamphetamine to get high, it also can be used to treat disorders such as attention-deficit hyperactivity disorder. Some athletes even use it to enhance their performance during sporting events.
motivator: A thing, event or idea that encourages an animal (or human) to behave or act in a particular way.
nausea: The feeling of being sick to one’s stomach, as though one could vomit.
nerve: A long, delicate fiber that transmits signals across the body of an animal. An animal’s backbone contains many nerves, some of which control the movement of its legs or fins, and some of which convey sensations such as hot, cold or pain.
neuron: The main cell type of the nervous system — the brain, spinal column and nerves. These specialized cells transmit information by producing, receiving and conducting electrical signals. Neurons also can transmit signals to other cells with chemical messengers.
neurotransmitter: A chemical released at the end of a neuron to carry a message to a neighboring cell. This chemical travels across the space between two cells, and then binds to molecules on a neighboring cell to transmit a message. Neurotransmitters are released from neurons, and can bind to neurons or to other types of cell, including those that make up muscles or glands.
nicotine: A colorless, oily chemical produced in tobacco and certain other plants. It creates the “buzz” associated with smoking. Highly addictive, nicotine is the substance that makes it hard for smokers to give up their use of cigarettes. The chemical is also a poison, sometimes used as a pesticide to kill insects and even some invasive snakes or frogs.
nucleus accumbens: An area deep within the front part of the brain that is linked to pleasure and motivation.
peer: (noun) Someone who is an equal, based on age, education, status, training or some other features. (verb) To look into something, searching for details.
physical: (adj.) A term for things that exist in the real world, as opposed to in memories or the imagination. It can also refer to properties of materials that are due to their size and non-chemical interactions (such as when one block slams with force into another).
prefrontal cortex: A region containing some of the brain’s gray matter. Located behind the forehead, it plays a role in making decisions and other complex mental activities, in emotions and in behaviors.
psychologist: A scientist or mental-health professional who studies the human mind, especially in relation to actions and behaviors. 
receptor: (in biology) A molecule in cells that serves as a docking station for another molecule. That second molecule can turn on some special activity by the cell.
reward: (In animal behavior) A stimulus, such as a tasty food pellet, that is offered to an animal or person to get them to change their behavior or to learn a task.
reward center: (Also reward system) A region of the brain that processes the pleasant reactions we get when we get smiles, gifts, pleasurable stimuli (including food) or compliments.
risk: The chance or mathematical likelihood that some bad thing might happen. For instance, exposure to radiation poses a risk of cancer. Or the hazard — or peril — itself. (For instance: Among cancer risks that the people faced were radiation and drinking water tainted with arsenic.)
social: (adj.) Relating to gatherings of people; a term for animals (or people) that prefer to exist in groups. (noun) A gathering of people, for instance those who belong to a club or other organization, for the purpose of enjoying each other’s company.
social media: Digital media that allow people to connect with each other (often anonymously) and to share information. Examples include Twitter, Facebook, Instagram, TikTok and WhatsApp.
stress: (in biology) A factor — such as unusual temperatures, movements, moisture or pollution — that affects the health of a species or ecosystem. (in psychology) A mental, physical, emotional or behavioral reaction to an event or circumstance (stressor) that disturbs a person or animal’s usual state of being or places increased demands on a person or animal; psychological stress can be either positive or negative.
striatum: Also called the corpus striatum, this is a cluster of neurons located in the middle of the brain, at about the level of your temples. It is part of a bigger region known as the basal ganglia. The striatum is important for planning movement and decision making. It also responds to things that are rewarding or pleasurable, such as food or even music.
substance abuse: Another term for drug abuse. It refers to a condition where people may become dependent or even addicted to alcohol, tobacco or other types of drugs (either street drugs or prescription medications). These people do not use drugs to treat a medical condition but as an unhealthy way to alter the way they think, feel or respond to outside stimuli.
symptom: A physical or mental indicator generally regarded to be characteristic of a disease. Sometimes a single symptom — especially a general one, such as fever or pain — can be a sign of any of many different types of injury or disease.
tobacco: A plant cultivated for its leaves, which many people burn in cigars, cigarettes, and pipes. Tobacco leaves also are sometimes chewed. The main active drug in tobacco leaves is nicotine, a powerful stimulant (and poison).
white matter: One of the two main tissue types found in the brain and spinal cord. It consists mainly of bundles of nerve fibers.
withdrawal: (in medicine) An almost disease-like syndrome that can develop after animals (including people) attempt to stop using a drug (including alcohol) to which they have become addicted. Shaking, sweating, trouble sleeping, anxiety, diarrhea, vomiting, abdominal cramping, muscle aches and flu-like symptoms can occur and last for days.
Webpage: National Institute on Drug Abuse. Drugs, brains, and behavior: The science of addiction. June 2020 update.
Journal: B. Lees et al. Effect of alcohol use on the adolescent brain. Pharmacology Biochemistry and Behavior. Vol. 192, May 2020. doi: 10.1016/j.pbb.2020.172906.
Journal: J.A. Silvers et al. Hunting for what works: Adolescents in addiction treatment. Alcoholism: Clinical and Experimental Research. Vol. 43, April 2019. doi: doi:10.1111/acer.13984.
Journal: G.F. Koob & N.D. Volkow. Neurocircuitry of Addiction. Neuropsychopharmacology Reviews. Vol. 35, 2010. doi: 10.1038/npp.2009.110.
Journal: N.L. Benowitz. Pharmacology of nicotine: Addiction, smoking-induced disease, and therapeutics. Annual Review of Pharmacology and Toxicology. Vol. 49, Oct. 3, 2009, p. 57. doi: 10.1146/annurev.pharmtox.48.113006.094742.
Journal: D.A. Dawson et al. Age at first drink and the first incidence of adult-onset DSM-IV alcohol use disorders. Alcoholism Clinical & Experimental Research. Vol. 32, December 2008, p. 2149. doi: 10.1111/j.1530-0277.2008.00806.x.
Journal: B.F. Grand and D.A. Dawson. Age at onset of alcohol use and its association with DSM-IV alcohol abuse and dependence: Results from the National Longitudinal Alcohol Epidemiologic Survey. Journal of Substance Abuse. Vol. 9, 1997, p. 103 doi: 10.1016/s0899-3289(97)90009-2.  
Journal: M.L. Cooper. Motivations for alcohol use among adolescents: Development and validation of a four-factor model. Psychological Assessment. Vol. 6, June 1994, p. 117.  doi: 10.1037/1040-3590.6.2.117.
Alison Pearce Stevens is a former biologist and forever science geek who writes about science and nature for kids. She lives with her husband, their two kids and a small menagerie of cuddly (and not-so cuddly) critters.
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