Did you ever wonder when does the brain fully develop? Although 18-year-olds are considered the limit of “adulthood,” having an adult brain is not related to biological age, nor is brain maturation. The brain is a complex organ that is part of the central nervous system (CNS) and is the largest and best-known part of the brain. It is located in the anterior and superior parts of the cranial cavity and is present in all vertebrates. Inside the skull, the brain floats in a transparent liquid, called a cerebrospinal fluid, which performs both physical and immunological protective functions.
Although it is necessary to exercise the brain or otherwise atrophy, like muscles, nevertheless it is not a muscle. It is not composed of myocytes – muscle cells – but millions of neurons, interconnected by axons and dendrites, to regulate each of the functions of the body and mind. From breathing to eating, to sleep, the ability to reason, to fall in love or argue with someone, everything goes through brain control.
Have you ever thought about brain plasticity? As we experience the world, we practice habits and learn new information, our brain changes, develops new connections, and repairs those that have been broken. As we age, our experiences and knowledge allow our brains to stay active, developing, and learning.
In the following lines, we will expose the maturity of our brain, and we will also try to answer when does the brain fully develops. Thanks for continuing reading.
1 – When Does the Brain Fully Develop?
Pediatrician Jay Giedd of the Bethesda National Institute of Mental Health (USA) in a 2007 study found that the human brain was under construction until late adolescence, although at this stage, neurons and nerve connections do not develop, they will “elude” until the reasoning of adulthood is reached.
All brains do not follow the same pace of evolution as they mature. The study seems to confirm that girls reach brain maturity sooner than boys. Although the factors that determine this phenomenon are not yet clear.
Girls Are Older Than Boys
Jay Giedd, who has conducted a 13-year study of a large sample of children and adolescents aged 4 to 26, found that girls are older than boys. For example, brain volume in boys peaks around age 15, while for girls it is almost 12 years old. In terms of brain maturity, a girl reaches full maturity based on brain development between 21 and 22 years of age. In the case of boys, however, it appears that the brain continues to develop and does not reach full maturity before the age of 30.
He also found that in smarter youths (boys or girls), brain maturation occurs at an earlier age. The discovery shows that the so-called “age of reason” is not reached at age 18, as is commonly believed, but many years later and usually depends on the particular individual as well as his sex. The research results can explain scientifically, among other things, why there are four times more road accidents involving young people than adults.
The Parental Effect in Childhood and Adolescence
According to Giedd, in addition to intelligence and gender characteristics, an enriched environment and stimulating activities can promote maturation of the prefrontal cortex and self-regulating abilities, but it is also important to underline the role of parental effect in childhood and adolescence.
There is much scientific evidence to support the link between parental neglect and lack of affection in children and a greater incidence of problems related to poor self-control at a later stage. It is highly likely that affective deficiencies prevent proper development of the prefrontal cortex, which would promote antisocial, reckless, or addictive behaviors.
2 – At What Age Does the Human Brain Mature?
A study from the London Institute of Cognitive Neuroscience, conducted in April 2011, suggests that the brain continues to develop after childhood and puberty and that it is not fully mature before age 30, and that does not even complete until it reaches its peak at age 40. The results contradict earlier theories that indicated much earlier brain maturation.
The results of the research suggest that the prefrontal cortex is the region with a longer developmental period. This area of the brain is important for higher cognitive functions such as planning and decision making. In addition, she plays a key role in social behavior, empathy and interaction with other individuals, and certain personality traits.
Magnetic resonance images taken from participants in various studies show that the cortex region continues to change until people reach the age of 30 and in some cases even 40 years. In the opinion of scientists, this region begins to change during early childhood, then restructures at the end of adolescence, and does not cease after, but continues to change.
*** The Prefrontal Cortex
Modern mammals, primates, and some cetaceans have a much more developed brain than primitive mammals. Thus, in addition to emotions, they manage a process of better understanding that is directly related to the development of the cerebral cortex, where we find one of the greatest developments of the brain on the evolutionary scale.
The neocortical or neocortex system, especially its frontal region, is the place where these higher intellectual processes take place and allow us to acquire knowledge, develop societies, cultures, and technologies. Most of the cerebral cortex of animals are engaged in sensory and motor functions, the opposite occurs in humans: the bulk of his brain is not engaged, but it is available for the realization of a future, not a program. The neocortex becomes the main focus of attention in lessons that require problem generation or problem-solving, information analysis and synthesis, the use of reasoning, critical and creative thinking.
Studies show that this area of the brain, so linked to reasoning, turns out to be the last to mature.
*** Not All Brains Mature at the Same Pace
When one speaks of maturity in absolute terms, time plays a fundamental role because, at birth, the human being does not have as many neurons or synaptic connections as in adulthood. Nor does he have the life experience necessary to inform these neurons and to model the synapses that allow him to reflect on the environment he has known during his life. Psychological maturity is a continuous process, the person does not reach maturity at a given moment, it is a gradual process.
However, maturity, just like intelligence, can vary a lot from one individual to another, which means that sometimes a younger person has a more mature behavior than the older one. Nobody is born mature. Our experiences, our intelligence, our sexual condition, and the way our parents raised us contribute to the way our character and our emotional development are shaped. So, even from this perspective, it is not easy to answer when does the brain fully develops.
What Is an Emotionally Mature Person?
An emotionally mature person is a stable subject who tolerates frustration, accepts responsibility for his or her own actions without taking refuge behind excuses, or has sufficient mental amplitude to reflect on the opinions of others. To have this emotional maturity, it is essential that our cerebral neocortex have an adequate degree of development.
All the evidence that neuroscience offers us confirms that our brain continues to develop after childhood and at puberty and that it is not “done” until we are over 30 years old. And for the moment, all this evidence has already led, to give just one example, in the United Kingdom, where psychologists have “delayed” the age of the end of adolescence to 25 years, to determine the method of administration of treatment to young people.
The latest findings may explain why some adults sometimes act like teenagers, experiencing sudden tantrums or mood swings when they fail to cope. This would also explain why some people have difficulty choosing, planning, and persevering in the tasks they initiate. These skills would be acquired once the brain is fully mature.
3 – The Brain Matures After 30 Years…
Leah Somerville, a neurologist at Harvard University in an article published in Neuron magazine in December 2016, explains in detail this riddle: when is the brain already something definitive? When is its development finished? When does the brain fully develop?
It happens that the human brain reaches its “adult” volume at 10 years, but the neurons that compose it continue to change for years, the development continues. The connections between neighboring neurons are rearranged, while new connections appear between the most widely separated areas of the brain.
New Links Are Formed at 30 Years Old, or Even Longer
Finally, this reorganization slows down, a sign of the maturation of the brain. But this happens at different rates in different parts of the brain and at different ages. Development in the occipital lobe, in the posterior part of the brain, decreases to 20 years. In the frontal lobe, in the anterior part of the brain, new links are formed at 30 years old, or even longer. This challenges the notion of what a “finished” brain really means. When does the brain fully develop?
If our brain changes anatomically, its activity also changes. In children, the neighboring brain regions usually work at the same time. But in adulthood, the most separated regions are those that end up synchronizing. According to neuroscientists, this “long-distance” harmony would allow the adult brain to work more efficiently and process more information.
*** The Differences Between the Adolescent Brain and the Adult Brain
Nevertheless, the development of these long-distance neural networks remains a mystery, and we do not know how they influence human behavior. In fact, some children already have this type of adult brain neuron network, but they are still children.
For its part, the adolescent brain is able to perform cognitive tests, as well as that of adults. In addition, a teenager’s emotions are too intense and can lead to a fall in these tests. The researchers suggest that the problem lies in the fact that the adolescent’s brain does not yet have a strong brain system that allows him to contain his emotions.
But that’s not all, and we know that there are young adults (aged 18 to 25) who still do not have a brain system of the adult brain capable of containing emotions, which makes them adolescents “at the cerebral level.
*** The Unknown Maturation of the Human Brain
Brain maturation can be a problem because of its long process and diversity among individuals. At the political level, for example, it has been proposed to reduce the voting age to 16 years. Yes, it is true that at the level of logical reasoning at this age, the adolescent brain and the adult brain are similar, but in politics, emotions have a powerful influence (even in adults).
Somerville suggests that more research is needed on the maturation and development of the adult brain, with large-scale follow-up studies of up to 20 years or more. It is not enough to make one-off comparisons between different people using brain imaging tests, you have to see these changes over time.
As the most recent scientific data shows, the brain is a very complex system and its maturation is not the same in all people. Obviously, we need more researches to find out when does the brain fully develops.
4 – When does the brain fully develop? Maybe never?
According to an article by researchers at Princeton University published in the journal Trends in Cognitive Sciences in February 2015, it was discovered that the adult brain continues to make neurons in the hippocampus, a region of the brain linked to learning. in memory, until the death of the individual. What is not yet known is how and why these new nerve cells are born.
According to research conducted on laboratory mice, it is increasingly evident that stressful experiences, such as lack of sleep, social rejection, or exposure to predator odors, slow the growth of nerve cells in the body. mammalian brain. On the contrary, pleasurable experiences, such as mating or physical exercise, stimulate neurogenesis.
Stressful Experiences Slow the Growth of Nerve Cells
This decrease in neuron production can manifest itself in various disorders, such as difficulty remembering or learning to move in different environments, as occurs with Alzheimer’s disease in humans.
Indeed, the brake on neurogenesis due to stress increases the chances of survival, the exploratory behavior being inhibited for the safety of the individual. On the other hand, increasing the number of nerve cells by gratification would reduce anxiety and improve the ability to learn and explore, factors essential to successful reproduction. However, when the levels of emotional tension are too high and continuous, a counter-productive response occurs: the interruption of the neuron factory can produce anxiety and depression disorders.
Pleasurable Experiences Stimulate Neurogenesis
Increasing the number of nerve cells by gratification reduces anxiety and improves the ability to learn and explore, two factors essential for the reproduction of the species.
Another discovery of the experiments is that high social status mice produce more nerve cells than subordinate mice, which can be extrapolated to social relations between humans.
The pace of production of new neurons has sparked debate among scientists as to whether these neurons generated in old age are manufactured continuously in case they are needed in the future, or only in certain circumstances such as those mentioned above.
Although these experiments were performed with mice, the results show that humans tend to respond similarly to similar stimuli throughout their lives.
5 – Every Day, 1,400 New Neurons Are Born in the Brain
A team of scientists from the Karolinska Medical Institute (Sweden), the study was published in the journal Cell in June 2013, has developed a technique based on the measurement of carbon 14 to determine the number of cells generated per day in the human brain.
To carry out their study, the researchers developed a curious method. During the 1950s, during the Cold War, nuclear tests led to an increase of carbon 14 in the atmosphere. Through photosynthesis, this carbon has been incorporated into plants and from there it has spread throughout the food chain. Years later, nuclear tests stopped and carbon levels 14 became lower again. When the cells duplicate their chromosomes, this carbon 14 is integrated into the genome and thus constitutes a unique marker indicating the age of said cells.
About 1,400 New Neurons Are Produced Every Day
The researchers analyzed the carbon 14 of adult cells in the hippocampus by mass spectrometry and concluded that about 1,400 new neurons are produced every day in our brains and that this rate decreases with age.
It has long been thought that we were born with a certain number of brain cells and that it was impossible to generate new neurons after birth. We then began to think that there was a certain rate of renewal, but we did not know in what quantity, nor its importance for brain function.
In this study, scientists have demonstrated that neurogenesis exists throughout life in the hippocampus, suggesting that new neurons could contribute to the functioning of the human brain.
6 – The Brain Keeps Growing
A team of neurologists from Columbia University (USA), in a study published in Cell Stem in April 2018, discovered that the brain is constantly growing, a finding that could help treat degenerative diseases such as Alzheimer’s.
Previously, researchers thought that the brain did not develop new cells after childhood, making it much more difficult for adults to learn new skills or learn a foreign language, for example.
More recent studies have suggested that if specific areas of the brain are hyper-stimulated, new cells may form. However, in this study, it has been concluded that thousands of new brain cells or neurons are forming all the time, even when people are very old. In a teenager’s brain, there are as many new neurons as in an old man. That is, they never stop being made.
Not so long ago, it was believed that alcohol and other substances destroyed neurons. New studies have shown that they can damage them, but they do not end with them. In fact, we now know that our brain keeps growing and creating new neurons. These neurons would be created at any time, even now in our own brain.
*** The Synapses of the Brain
According to these results, the abilities lost as a function of age are not linked to the lack of neurons that die, but to the lack of communication of these brain cells.
That is, the neurons of the human hippocampus are still born, whether we are younger or older. However, poor vascularization of aging organisms prevents new neurons from making good connections.
And here lies the importance of this discovery. Now, it may be easier to discover the causes of dementia, so it will be much easier to prevent them. This progress comes at an opportune moment, as neurodegenerative diseases continue to grow.
Therefore, this experience, which observed the hippocampus in individuals aged 14 to 79, died suddenly is so important. Among individuals, there was no episode of depression or cognitive decline. In all their brains, it has been observed that the formation of neurons did not stop. In fact, they had been made new until the last moment. The only difference was that, in the elderly, the new blood vessels were less numerous among the brain structures and that they had fewer sperm cells, that is to say, stem cells that are eventually converted into young neurons.
Obviously, this new discovery has fantastic implications in medicine. From now on, neurodegenerative diseases such as the very dangerous Alzheimer’s could be treated much more effectively.
7 – The Part of the Brain That Does Not Mature Before 36 Years
A team from McMaster University (Hamilton, Canada) found in a study published in The Journal of Neuroscience in May 2017 that the primary visual cortex did not mature at the age of five or six, as thought so, but was evolving until about 36 years of life. This primary cortex is the first area of the brain that processes visual information and then drifts it to about 20 more specialized areas.
The primary visual cortex (or V1) is a region of the brain as wide as a hand. It receives and processes the visual information that arrives from the retinas, in the eyes, and that has already crossed the trunk and the thalamus. With a total of about 280 million neurons, V1 processes information about static and mobile objects and pattern recognition. In addition, it sends information to other parts of the visual cortex specialized in specific functions, such as the recognition of faces, words, or gestures.
*** The Importance of Plasticity
In the research, brain samples of 30 people who died between the first hours of life and eighty years were analyzed. Researchers have discovered that a group of proteins – called glutamatergic – are active for a good part of life and do not “go out” during childhood. One of its functions is to regulate the phenomenon of synaptic plasticity because they are able to strengthen or weaken synapses (connections) between neurons. Because of this, millions of cells in this region of the brain can change the way they are “wired”. At least until age 36, with a margin of four and a half years above and below.
Even a primary sensory area, which is the first part of the cortex that processes visual information, evolves and develops throughout life. It undergoes a series of orchestrated changes, which probably respond to changes in visual perception.
All of this means that even a cerebral region with a basic, low-skilled function is flexible and develops for decades, which in turn translates that the human vision continues to evolve into the third decade of life.
*** Specific treatments for each person
As researchers have found, glutamatergic protein activation levels change over time. This is important when seeking treatments for vision-related ailments. For example, the authors recalled that treatments for tired eyesight have always been designed taking into account that only children can benefit from corrective therapies because it is considered that the adult brain can no longer respond. But its progress could lead to a reconsideration of this question.
Other diseases could benefit from this research: Visual disorders related to aging or diabetes, glaucoma or macular degeneration may be better treated with this finding. The challenge is to be able to translate this knowledge into effective treatments for each person and directed to a specific target.
The next step that the team will undertake will be to analyze the development of regions related to the recognition of faces or emotions, in order to understand their development and their way of specializing over the years.
Scientists are increasingly convinced that the brain is a plastic organ in constant evolution. In fact, they are slowly discovering that this flexibility is not just for children or young people: the adult brain is also able to adapt to big changes, such as learning to read or discover a new language.
8 – The Epigenome of the Brain Changes from Birth to Adolescence
Researchers from the Epigenetics and Cancer Biology Program of the Bellvitge Biomedical Research Institute (Barcelona) find in an article in Science in July 2013 that the frontal cortex – the part of the brain responsible for the behavior and the acquisition of new information from people – undergoes a significant change from birth to late adolescence: their epigenome – a set of chemical signals that activates or deactivates DNA genes – is transformed.
The study was based on the analysis of the epigenome of newborns, 16-year-olds, and 25- and 50-year-old adults in the United States and Catalonia. The discovery shows that one of these epigenetic signals, called methylation of genetic material, progressively increases through late adolescence to adulthood. As a result, behavioral changes occur in us, from babies to teenagers.
Methylation of DNA Is Essential
The results of the study reveal that this methylation of DNA is essential in the formation of communication spaces between neurons (synapses). The methylation of DNA in neurons is different from the rest of the cells in our body. The researchers explain that if the normal is called 5-mCG, it’s called 5-MCH: it’s like putting an open or closed accent on a word, in this case, a gene, to change its meaning.
This discovery could be of great importance in the knowledge of the biology of the brain because, in addition to explaining the plasticity of this organ before learning and life experiences, it can be decisive to understand the causes of changes in behavior and behavior. psychiatric diseases.
We must now examine whether small modifications of the DNA methylation program in postnatal development may be related to neurodevelopmental disorders such as autism or schizophrenia.