Teen Brain Development: Timeline, Effects, Factors

Emotional center
Reasoning center
Reward centers
Other processes
Healthy practices
Caregiver tips
Learn more

Teens are more likely to engage in high risk behavior, misinterpret social cues, and react rather than act proactively. To understand why, look to adolescent brain development.

Brain development begins during gestation. A newborn’s brain is 25%Trusted Source of its adult size, ultimately reaching 90–95% of its adult size by age 6. Then, until about age 25, the brain undergoes a “remodeling” process.

Unnecessary brain cells are eliminated during this time, says Igor Smelyansky, MD, a neurologist and pain management specialist in Knoxville, Tennessee.

Brain cells needed to live and function strengthen their connections with other cells, he explains.

This process begins in the back of the brain (in the limbic system, or emotional center) and slowly moves forward (toward the prefrontal cortex, or reasoning center).

The remodeling process speeds up during your teenage years, and usually peaks between ages 13–15, he says.

No brain is the same

Just as children’s bodies grow and develop at different ages, rates, and speeds, so do their brains. How that looks (to the outside world) and feels (for them) varies teen-to-teen.

“What’s important is that as a teen you know that your brain is changing and that as a parent you know that your teen’s brain is changing,” says Smelyansky.

“Most brains don’t reach full maturation until 23–25 years of age.”

The emotional centers of the brain (the limbic system)

The brain plays a crucial role in how people of all ages control, process, and express emotions.

More specifically: a part of the brain known as the limbic system.

“The limbic system is a group of interconnected structures located deep inside the brain,” explains Smelyansky.

This includes the:

hippocampus
amygdala
hypothalamus
limbic cortex

These structures work together to:

facilitate memory storage and retrieval
establish your emotional state
link motivation with behavior
regulate autonomic function

The limbic system is the first part of the brain to complete the remodeling process. It’s usually done in early adolescence between ages 10–13.

The reasoning center of the brain (prefrontal cortex)

Colloquially known as the reasoning center of the brain, the prefrontal cortex is responsible for decision-making, self-control, and understanding consequences, explains Smelyansky.

It’s the last area of the brain to remodel and mature.

When the prefrontal cortex is fully developed — which typically happens around age 25 — you’re considered capable of discerning the relationship between your actions and potential short- or long-term consequences.

Until then, adolescents and young adults rely on the amygdala to make decisions, says Smelyansky.

“The amygdala is where primitive emotions, urges, impulses, fears, aggression, and primitive desires are located,” he says.

In practice, this usually looks like acting before thinking things through or otherwise acting impulsively.

The reward center of the brain (mesolimbic system)

Known medically as the mesolimbic system and colloquially as the hedonistic hotspot, the reward center of the brain is in charge of pleasure.

It’s the part of the brain that lets you know when you “like” something, or when something is a net “positive.”

The mesolimbic system connects a part of the brain known as the ventral tegmental area (located in the middle of the brain) to the ventral striatum (located at the forefront of the brain).

This pathway is lined with dopamine-releasing neurons, which fire at an increased rate when you anticipate a reward or source of pleasure.

“Increased release of dopamine is involved in reinforcing and motivating behaviors,” explains Nicole Prause, PhD, a clinical scientist who specializes in neurology.

During adolescence, this pathway undergoes an extensive changeTrusted Source to its structure and function, which results in higher dopamine levels.

As a result, teens are thought to be especially susceptible to substance misuse, alcohol misuse, and other thrill-seeking behaviors.

Other aspects of brain development

There are two other notable processes that occur during brain development that influence how a teen acts, reacts, feels, and thinks: Pruning and myelination.

Pruning occurs when the brain gets rid of synapses it no longer needs. Synapses are structures that allow different neurons to communicate.

Neurons, also called nerve cells, use electrical and chemical signals to communicate with different areas of the brain and body.

Synaptic pruning occurs twice during brain development, once during early childhood (between ages 2–10) and once during late adolescence or early adulthood (teens to late 20s).

Some research suggestsTrusted Source that adolescents may be more likely to take risks during the second synaptic pruning.

Myelination occurs when neurons are wrapped in an insulating layer of protein and fatty substances (myelin). This enables neurons to communicate more efficiently and effectively.

Although myelination begins early in life and continues into adulthood, its production escalates during adolescence. This increases the speed of information flow, which can make everything feel BIG.

When all is said is done, pruning and myelination help teens process and respond to information more quickly, weigh risk and reward, and think more critically.

What can you do to promote healthy brain development?

To start, do what you can to avoid concussions and other head injuries.

“Avoiding injuries to the brain is always important, so it’s best to wear basic head protections (like helmets) when you play tackle or impact sports,” says Prause.

Beyond that, anything that’s good for a teen’s overall health is good for brain development, says Sony Sherpa, MBBS, a holistic health practitioner.

“Teens should prioritize getting 8–10 hours of sleep per night, as this helps the brain absorb information learned throughout the day,” says Sherpa.

“Eating a balanced diet that includes dark green leafy vegetables, fruits, legumes, nuts, and lean proteins is also essential for providing the brain with the nutrition it needs to function optimally,” she says.

“Regular physical exercise and social connection help reduce stress, improve mental focus, and maintain overall brain health,” says Sherpa.

According to the Centers for Disease Control and Prevention (CDC)Trusted Source, teens should aim for at least 60 minutes of moderate or high intensity physical activity per day.

“Taking time for self-care activities, such as meditation or yoga, can help reduce stress and increase resilience,” says Sherpa. “Managing stress levels can be beneficial for concentration and problem-solving skills.”

Finally, engaging in mentally stimulating activities, like solving puzzles and reading, can help promote critical thinking skills, attention span, and overall mental acuity, she says.

How can parents and guardians offer support during this time?

It’s important to understand that your child’s brain is still developing during their teenage years, as well as how the order and speed of that development can impact their ability to make decisions, says Prause.

Remember, the reasoning center of the brain (the prefrontal cortex) develops later in adolescence than the emotional center of the brain (the limbic center).

“The result of this is that teens act quickly with less forethought than older youth and adults as they learn the consequences of such behaviors and have the ability to reduce their impulsivity,” she says.

During this time, she says, it may be useful to keep in mind that your child isn’t ”stupid,” but is still in the process of learning how quickly they can make and act on decisions.

“You can also help facilitate this learning process by explicitly helping them think through the potential consequences of certain decisions,” she says. “Or, by allowing them to make learning errors unlikely to injure them, they will eventually reduce their impulsivity.”

In practice, that might look like you making the following suggestions:

”Before you do that, let’s slow down and think about the potential outcomes.”
”I know this feels really big right now. So let’s step away from it for a few hours, then tonight we can return and make a decision then.”
”Why don’t we sleep on it?”