The Effect of Drugs on the Teenage Brain: Risks, Development, and Support

Adolescence is a critical time of brain development, marked by rapid physical, emotional, and cognitive changes. It is also a period of growing independence, exploration, and often, risk-taking. One of the most significant risks teens face today is the use of drugs, including alcohol, marijuana, nicotine (including vaping), and prescription medications.

Adolescence can be divided into three key stages:

• Early Adolescence (Ages 10 - 14): Characterized by the onset of puberty, noticeable physical changes, and heightened emotional and social awareness.

• Middle Adolescence (Ages 15 - 17): A time when teens become increasingly self-conscious, explore their identity, and prioritize peer relationships.

• Late Adolescence (Ages 18 - 21): Marked by the completion of physical development, more advanced cognitive abilities, and continued exploration of relationships and identity.

These formative years represent a window of opportunity, but also vulnerability. The adolescent brain is still maturing, especially in areas responsible for decision-making, impulse control, and emotional regulation. As a result, drug use during this period can have profound and lasting effects. Several interrelated factors, including genetics, environment, trauma, peer influence, and emotional health, contribute to changes in a young person’s brain structure and function. Although the most serious consequences of substance use often emerge in late adolescence or early adulthood, the patterns and damage are frequently set in motion much earlier. Understanding how substances affect the developing brain can empower parents, educators, and teens themselves to make informed, healthier decisions.

Brain Structure The human brain is not fully developed by the time of puberty. While the cerebral cortex, the outer layer of the brain responsible for higher-level thinking, reaches about 90% of its adult size by age six or seven, structural maturation continues well into a person’s mid-20s.

Between the ages of 10 and 25, the brain undergoes significant changes that influence how adolescents think, feel, and behave. One of the most important developments during this time is the remodeling of the cortex, particularly in areas that manage cognitive control, emotional regulation, and social reasoning.

These brain changes include:

• Synaptic pruning: The brain eliminates unused neural connections, making it more efficient.

• Myelination: Nerve fibers are coated with myelin, speeding up communication between brain regions.

• Reorganization of the prefrontal cortex: This area, critical for planning, decision-making, and impulse control, is one of the last to mature fully.

The folds of the brain, or cortical gyri, continue to change in adolescence, especially in the frontal and parietal lobes, which are responsible for executive function and emotional processing. This means teens are still learning how to weigh consequences, regulate their emotions, and make sound decisions—skills that are especially vulnerable to the effects of drug use.

Limbic System The limbic system, a network of brain structures involved in emotion, motivation, and reward, develops years ahead of the prefrontal cortex, the brain’s center for rational thinking and self-control. This developmental gap contributes to the emotional intensity and risk-taking behaviors often seen in adolescents. The limbic system plays a crucial role in processing emotional experiences, interpreting social cues, determining rewards and punishments, and motivating behavior in response to environmental feedback.

Two key neurotransmitters, dopamine and serotonin, are especially active in this part of the brain during adolescence:

Dopamine is a neurotransmitter closely associated with:

• Pleasure

• Motivation

• Risk and reward processing

• Learning from experience

During adolescence, dopamine levels in the limbic system rise significantly. This heightened activity makes teens more responsive to rewards, which can reinforce risky behaviors, especially in peer-driven environments. Additionally, the increased influx of dopamine to the prefrontal cortex influences how adolescents interpret and respond to their surroundings during decision-making.

Serotonin helps regulate:

• Mood

• Impulsivity

• Aggression

• Stress and tension

While dopamine fuels excitement and reward-seeking behavior, serotonin plays a stabilizing role, helping teens pause, reflect, and regulate emotions. When serotonin levels are imbalanced or poorly controlled, adolescents may experience heightened impulsivity, mood swings, or even aggressive behavior. Deficits in serotonin processing have been linked to impulsivity, depression, and violent behavior in both adolescents and adults.

Common Substances Alcohol: Alcohol can disrupt normal brain development in teens. Teen drinkers are at a higher risk of developing alcohol dependence later in life.

Marijuana: Can impair memory, attention, and learning in adolescents. The teen brain’s plasticity makes it more susceptible to long-term changes from THC exposure.

Nicotine (including Vaping): Nicotine is highly addictive, and vaping has become one of the most common ways teens consume it. Despite marketing that makes vaping appear "safer," some e-cigarettes can expose the brain to equal or even greater levels of nicotine than traditional cigarettes. Exposure during adolescence can interfere with brain development, particularly in areas responsible for attention and learning.

How Common Substances Affect the Brain: Drugs and alcohol flood the brain with unusual amounts of neurotransmitters, signals that tell you what to feel, and weaken its ability over time to feel pleasure naturally. Drugs also favor the more reactive part of the brain called the amygdala, which stimulates anxiety, irritability, and unease, rather than the more rational frontal cortex.

Alcohol: Alcohol doesn’t just cause temporary changes in behavior; it alters the brain's physical structure and function, especially in adolescents. Because the teenage brain is still developing, alcohol can interfere with critical processes such as learning, memory, emotion regulation, and decision-making. Here is how alcohol affects brain development:

• Decreased Gray Matter Volume: Chronic or heavy alcohol use during adolescence leads to reduced gray matter volume, especially in the prefrontal cortex and hippocampus. This loss can impair judgment, learning, and emotional regulation.

• Decreased White Matter Growth and Integrity: Alcohol disrupts the myelination process, weakening the connections between brain regions. This can result in slower thinking, poor coordination, and reduced emotional regulation.

• Increased Cerebrospinal Fluid Volume (CSF) in the Cerebellum: Increased CSF in this region may suggest shrinkage or underdevelopment of cerebellar tissue. This can contribute to poor balance, delayed motor skills, and coordination issues.

• Altered Brain Activation During Executive Functioning: Adolescents who use alcohol show increased activation in the frontal and parietal regions during tasks requiring executive function. Their brains may be working harder to perform tasks that should be efficient.

• Decreased Brain Activation During Reward Sensitivity Tasks: Alcohol use affects the striatum and prefrontal cortex, reducing sensitivity to positive reinforcement. This can lead to increased risk-taking behavior.

• Increased P3 Amplitude During Attention Tasks: Alcohol use is associated with increased P3 amplitude in the brain's fronto-parietal regions, indicating overactivation or compensatory effort during attention-demanding tasks.

Marijuana: THC, the primary psychoactive compound in marijuana, crosses the blood-brain barrier and binds to CB1 receptors in the brain. These are part of the endocannabinoid system (ECS), which regulates:

• Stress response

• Anxiety

• Memory and learning

• Pain perception

• Motivation and reward

• Emotional processing

The ECS plays a central role in neural development, especially during adolescence. When THC binds to CB1 receptors, it disrupts natural ECS signaling, impairing brain development. Chronic or heavy marijuana use during adolescence has been linked to:

• Thinner prefrontal cortex

• Reduced cognitive performance (attention, memory, learning)

• Altered brain connectivity between the prefrontal cortex and hippocampus

• Increased risk of mood disorders

• Impaired motivation ("amotivational syndrome")

Brain imaging shows long-term changes in brain structure in adolescents who use marijuana regularly.

Nicotine (Vaping): Nicotine hijacks the dopamine system, which is responsible for pleasure and motivation. When inhaled, nicotine triggers a powerful dopamine release, creating strong reinforcement for use. Repeated exposure can:

• Lead to addiction by altering dopamine pathways

• Decrease sensitivity to everyday pleasures

• Increase withdrawal symptoms and emotional volatility

Nicotine also affects neurotransmitters that are still maturing during adolescence:

• GABA: regulates anxiety

• Glutamate: involved in learning and memory

• Serotonin: regulates mood

• Acetylcholine: affects attention and learning

Nicotine interacts with nicotinic acetylcholine receptors (nAChRs), which are more sensitive during adolescence. Long-term use has been associated with:

• Increased risk of anxiety and depression

• Impaired emotional regulation

• Disruption of mesolimbic reward pathways

Though vaping may provide short-term focus or calm, it worsens emotional distress over time, creating a cycle of dependence.

Consequences of Addictive Behaviors: Adolescents are naturally drawn to new experiences, which increases the risk of substance use and addictive behavior. Risk factors include:

• Psychological: Low self-esteem, trauma, anxiety, depression

• Individual: Genetic predisposition, impulsivity, sensation-seeking

• Family: Lack of supervision, family substance use, poor attachment

• Social/Environmental: Peer pressure, exposure, lack of activities

• Social Media: Glorification of risky behaviors and substance use

Long-term consequences include:

• Neurobiological: Changes in the brain’s reward system and decision-making centers

• Academic: Decreased performance and goal setting

• Cognitive: Memory, attention, and executive functioning deficits

• Social/Emotional: Difficulty in relationships and identity formation

• Physical Health: Increased risk of respiratory and cardiovascular issues, and substance use disorders

Prevention Strategies:

• Education and awareness

• Family engagement

• Mental health support

• Positive peer and community involvement

• Digital literacy

Substance use in adolescence is not a moral failing; it is a developmental and public health issue. With education, support, and early intervention, we can empower teens to thrive emotionally, socially, and academically.

If you’re concerned about your teen or simply want to take a proactive approach to their mental and emotional health, The Kraft Group Inc. is here to support you. We offer individualized care tailored to the unique developmental needs of adolescents, as well as family-centered services that promote connection, communication, and healing. Together, we can break cycles of substance misuse and build a foundation for lifelong well-being.

Resources:

• SAMHSA’s National Hotline: 1-800-662-HELP (4357) | www.samhsa.gov/find-help/national-helpline

• Crisis Text Line: Text HOME to 741741 | www.crisistextline.org

• Partnership to End Addiction (for Parents): https://drugfree.org

• NIDA for Teens: https://teens.drugabuse.gov

• Your Life Your Voice: https://www.yourlifeyourvoice.org

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