When Is The Brain Fully Developed?

brainFor many years, it was thought that brain development is set at a very early age. By the time teen years were reached the brain was thought to be largely finished. However, the scientists have recently discovered, using different techniques, that the brain continues to change into the early 20’s  with the frontal lobes, responsible for reasoning and problem solving, developing fast. Only now it appears that behaviors of young teenagers don’t have to necessarily be the result of raging hormones, but the result of neurobiology. Basically, that means that someone who is considered legally “an adult” (those age 18+), has to make important decisions of their lifetime. Those decisions may be the consequence of underdeveloped  brain and not immaturity as it is widely considered among parents.


Adolescence is the period  between childhood and adulthood encompassed by the changes in physical, psychological, and social development. These changes make this specifical period of time in human’s life a time of vulnerability and adjustment. According to some statistics, there are over 13,000 adolescent deaths in the United States each year, and approximately 70% of  these deaths are consequences of  motor vehicle crashes, unintentional injuries, homicides, and suicides. These worrying statistics show how much behaviors of certain individuals affect not only people around them but also themselves (and sadly, the way their life can end).

During adolescence, the social environment is changing , which leads to numerous conflicts among teenagers and their parents. These changes in social interactions may influence of the rise of emotional reactivity. A number of cognitive and neurobiological hypotheses have been postulated to explain why adolescents engage in the suboptimal choice behavior. In a recent study on a human brain development, Yurgelun –Todd suggests that cognitive brain development during adolescence is associated with progressively greater efficiency of cognitive control and affective modulation. Increased activity in the prefrontal regions is described as a neurobiological explanation for the behavioral changes associated with adolescence. This general pattern of improved cognitive control and emotion  regulation with the maturation of the prefrontal cortex, suggests a linear increase in development from childhood to adulthood. Adolescent behavior is repeatedly characterized as impulsive and risky, although different studies suggest different biological substrates for two types of  behavior.

Some findings suggest that during adolescence, some individuals have the predisposition to engage in risky situations due to developmental neural changes. Therefore, impulsivity is associated with the immature ventral prefrontal development and gradually diminishes from childhood to adulthood.

The Changes Of The Brain During Development

The brain experiences major growth and changing from adolescence until adulthood. There are a couple key ways by which the brain changes during stages of development. Those stages include:


Myelin is a fatty white substance that surrounds the axon of some nerve cells, forming an electrically insulating layer. It  is essential for the proper functioning of the nervous system. The production of the myelin sheath is called myelination or myelinogenesis. This process appears among humans begins in the 14th week of fetal development, although myelin exists in the child’s brain from the moment of  birth. During infancy, myelination occurs quickly and continues to the adolescent stage of  life. The loss of myelin sheath can cause some neurodegenerative autoimmune diseases, including multiple sclerosis, transverse myelitis, central pontine myelinolysis, inherited demyelinating diseases such as leukodystrophy, Charcot – Marie – Tooth disease and many others.

Synaptic Pruning

This process can be described as the process of synapse elimination between early childhood  among many mammals, especially humans. Pruning starts  near the time of birth and it is completed by the time of sexual maturation in humans. The infant brain will increase in size by adulthood, and one of the factors that contribute to this growth is, already mentioned, myelination. The other factor is the growth of synaptic connections between neurons. After adolescence, the volume of synaptic connections decreases again due to synaptic pruning.

Increased Connectivity

The connection between brain regions is more strengthened, making communication more efficient. The brain is able to transmit greater amounts of information between regions.

Executive functions

A great majority of executive functions that human being develops are via the prefrontal cortex. Although many of those functions (such as planning, taking risks, setting our goals, evaluating ourselves) are developed during teenage years, they are still under slight development until our mid  20’s. With that being said, it is important to define prefrontal cortex and its functions.

Prefrontal Cortex

The prefrontal cortex is the cerebral cortex which covers the front part of the frontal lobe. It contains Brodmann areas 9, 10, 11, 12, 46 and 47. Many authors have indicated a link between prefrontal cortex and a person’s personality. The most typical psychological term for functions carried out by the prefrontal cortex area is executive function, which relates to abilities to differentiate among conflicting thoughts, determine good or bad, better and best, same and different, future consequences of current activities, working toward a defined goal, prediction of outcomes, expectations based on actions, and social “control” .

The prefrontal cortex is highly connected with the brain; the dorsal prefrontal cortex is especially interconnected with the regions involved with attention, cognition and action while the ventral prefrontal cortex interconnects with the brain regions involved with emotion. We are going to enumerate some of  its important functions:

Executive Function. The prefrontal cortex is presumed to act as a high-level gating mechanism that enhances goal – directed activations and inhibitions irrelevant activations. This filtering mechanism enables executive control at various levels of processing, including selecting, maintaining, updating, and rerouting activations. It has also been used to explain emotional regulation. Experimental data indicate a role for the prefrontal cortex in mediating normal sleep, dreaming and sleeping deprivation phenomena. When we analyze and think about attributes of other individuals, the medial prefrontal cortex is activated. However, it is not activated when thinking about inanimate objects.

Attention And Memory. A widely accepted theory regarding the function of the brain’s prefrontal cortex is that it serves as a store of short – term memory. This idea was first formulated by Jacobsen in 1936. and most recently, Goldman – Rakic and colleagues (1993). As the brain continues to grow, our memorization and cognitive functions will widely improve over the years.

Decision Making And Complex Planning. The prefrontal region is responsible for complex planning as well. Every time we make a decision, we don’t know that prefrontal region helps us in the process. On the other hand,  it also helps us in the process of complex planning. No wonder that only after we reach a certain age,  we can plan things more easily. It is because our prefrontal cortex  has developed over the years.

Logical Thinking And Organized Thinking. As we get older , it gets much easier to organize things and solve some harder math problems. The organization and logical thinking are also one of the results of developed prefrontal cortex.

Personality Development And Attention. It is interesting how without proper stimulation of our cortex, we may struggle with identity issues and focus on things that matter to us. People with attentional deficits may have abnormalities within the prefrontal region. The same thing happens if we use alcohol or drugs.

Risk Management. As we mentioned at the beginning, some teenagers can’t decide if a risk will have a benefit for them or not. This could be a result of underdeveloped prefrontal regions.

What Are The Detrimental Influences Upon Brain Development?

Many people are exposed to things that may have a detrimental  impact on the development of their brain. Those detrimental influences include alcohol and drug abuse, chronic stress, poor diet, social isolation, sleep problems and even certain relationship troubles. All of these issues affect the daily life of modern young teenagers, and they might become a big problem. That’s exactly why it is strongly recommended for them to minimize exposure to problematic stimuli and scenarios.

Brain Development Promoting

There is some promoting behavior which you can use to stimulate the brain development. These include food choices such as vegetables, fruits, and avoiding fast food, artificial sweeteners and ingesting good sugars, proteins and lipids. There are also cognitive challenges which promote brain development stimulation. It is important to get enough sleep and to balance between stress and relaxation via meditation, exercise and socializing. You can also implement some supplements such as omega – 3 fatty acids, antioxidants.


Neuroscientists agree that the human brain hasn’t really developed until the mid 20’s. As most scientist claim, the brain is fully developed by the age of 25. Our executive functions, memory, and attention, as well as our complex planning and decision making and complex planning, will develop over time. Therefore, we can’t expect teenagers to make good crucial decisions for themselves, simply because their prefrontal cortex isn’t developed yet. Due to the process of myelination, our nerve system will continue developing even after we turn 18. Our brains are constantly adapting to the circumstances we live in, environment and experiences. We can damage the process of  brain development by alcohol and drug abuse, but also with the amount of stress we face every single day. That’s why we need to take care of our lifestyle, because even though we might not notice, it will affect our brain permanently.