Adolescent brain development

Adolescent brain development

The brain develops very rapidly in the first 3-5 years of life, and all the structure and building blocks are present by the age of 9. The different centres of the brain develop and become functionally connected over time. The last part to mature is the pre frontal lobe. This happens during adolescence.

Key points to remember

  • a safe environment where teenagers have consistent loving support is vital for the brain to develop well
  • adults who talk to children as they are growing up really help
  • when you are talking to teenagers be careful to check what emotion they are seeing in you, and make sure you always acknowledge their emotions first and then help them to be able to think about what they are feeling
  • young people need adults to believe in them and encourage them
  • teenagers respond better to rewards than to punishment
  • they need clear, consistent boundaries, and very importantly their growing capacity and ability to do things independently needs to be respected

When does brain development happen?

The brain develops very rapidly in the first 3-5 years of life, and all the structure and building blocks are present by the age of 9. The different centres of the brain develop and become functionally connected over time. The last part to mature is the prefrontal lobe. This happens during adolescence. Many things affect brain development including genetics, individual and environmental factors.  

Why does the brain take so long to develop?

Human beings are the only animals that are born completely helpless, and we have the biggest size of adult brain. If we were born with an adult sized brain our heads would not fit through our mothers' hips.

We used to think that once children had gone through puberty and growth had finished, development was complete. Then MRI scanners were invented and they showed that the brain goes on changing for a long time after puberty has finished, and may not be complete until nearly 30 years of age.

The following image shows that the brain doesn't change much in size between 5 and 20 years of age. What changes is the colour. The blue colour shows all the connections happening between all the parts of the brain that are already formed.

Image of brains showing increasing blue colour from 5 to 20 years of age

How does the brain develop?

Some people like to think of the brain in 4 parts:

  1. The spinal cord and the base of the brain that delivers messages to and from all parts of the body and controls what happens in the parts you don’t have to consciously think about like the heart, lungs and digestion.
  2. The cerebellum that controls and coordinates movement and other brain processes.
  3. The amygdala and hippocampus that control emotion and memory.
  4. The cortex which connects up all the senses and thinking part, including the prefrontal cortex which is involved in fine judgement and control.

The brain is thought to develop and connect functionally in stages. The emotional areas of the brain (the limbic system) are present at birth, but regulation of emotions moves from being more of a shared responsibility (with parents) in childhood, to an individual responsibility in adolescence. This process requires new connections to be formed between the cortical or higher level thinking and the emotional areas of the brain. It also leads to adult level decision making, planning and thinking.

Which part of their brain do teenagers use most of the time?

Experiments have been done to show that teens often 'think with their feelings'. Scans of the brain can be done to show different parts lighting up when they are being used. When adults and teens look at faces showing different emotions, the part of their brains that light up are different. Adults use their prefrontal cortex to look at faces and try to decide what emotion is happening. Teenagers use their amygdala rather than their prefrontal cortex most of the time. In other words, they are using their emotions to try and understand emotion.

To understand how this feels, imagine you have lost your keys and you are already late for work. Think about how many times you look for the keys in the same place – 5, 10 even 20 times. You panic – you no longer think with your cortex, you are thinking with your emotions. Remember how it feels if someone tells you to calm down and think sensibly about when you last had them. That is how your teenager feels when they are running on their emotions because their brain hasn't developed that linkage.

Often teens can misinterpret emotions and they see anger when in reality you are feeling anxious. This can often lead to many moments of miscommunication. So when you are talking to teenagers be careful to check what emotion they are seeing in you, and make sure you always acknowledge their emotions first and then help them to be able to think about what they are feeling. 

What can help brain development?

Adults who talk to children as they are growing up really help. A safe environment where they have consistent loving support is vital for the brain to develop well. Young people need adults to believe in them and encourage them. Teenagers respond better to rewards than to punishment. They need clear, consistent boundaries, and very importantly their growing capacity and ability to do things independently needs to be respected.

As their brain grows and gets connected functionally, they need to learn that they don't have to be dependent on their parents but can become interdependent with other adults as they mature. They need opportunities to grow many different skills and to contribute those skills in a way that is valued. The brain develops in a way that produces lots of connections that are then removed if they are not used. So take care to encourage lots of connections to be used.

Another principle is that when connections 'fire together they wire together', so this is a vital time to develop good habits around activities like thinking in a positive way, eating and exercise as that wires together for adulthood. We know that the brain can change throughout life but it is much easier to get the 'wiring right at the start, in teenage times'. It takes a lot of hard work to rewire as adults.

What harms the development of the brain?

It is now well established that if children experience any sort of abuse (verbal, emotional, physical, sexual or neglect), especially in the early years of life, it affects how their brain wires up and functions. Sometimes this is hard to change so it is very important to protect children all through their development. This is especially important at times of peak brain development in those first few years and during the second phase of brain development around puberty and afterwards.

Alcohol is like a poison to the developing brain. It is now well established that when the baby is developing in the mother's womb, alcohol can cause damage. We used to think that it was only if the mother drank a lot of alcohol but now we know that just one drink can cause a lot of damage at certain times of brain development.

It may be the same in the 'second stage' of brain development with all those connections that are happening after puberty. There is now more and more evidence to show that the brain can be very damaged by alcohol at this stage, especially affecting memory. If parents want to help their children's brains to develop well then don't let them have any alcohol until they are at least 18 and later if they started puberty later.

Image
Figure 3 from article 'Dynamic mapping of human cortical development during childhood through early adulthood'. Volume 101, issue 21.
Copyright 2004. National Academy of Sciences, U.S.A.
Our grateful thanks to the National Academy of Sciences, U.S.A. for permission to reproduce the image on this page. Please note this image is copyright and requests to reproduce it elsewhere must be made to the copyright holder. 

This page last reviewed 23 June 2015.
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