2023-11-13 09:20:33
by Elena Meli
Full physical maturity is reached around the age of thirty, but the brain does not stop evolving and continues to change even if the number of nerve cells decreases with age.
After the age of 20, a little earlier in the case of girls, one no longer grows in height; after puberty we biologically become adults and are able to reproduce. From the point of view of evolution, therefore, the games could be played around the age of 25, 30: we are well grown and we have already been able to perpetuate the species, having children and taking care of them just enough to make them independent, so if we move on to better life the world will go on the same. And it went like this for millennia, when the average life expectancy was very low: one could therefore think that the development of the organism, in all its parts, is aimed at making us complete people in every way, physically and mentally, around twenty years. For the body this is the case, but for the brain it’s a different story: it never stops evolving, learning, growing and its adolescence is much longer than the rest of the body.
The brain can always learn
Scientific research is in fact discovering that it takes many more years for humans to have an adult brain than other mammals, but also that the now grown brain is not a monolith where cells no longer reproduce and which can only lose neurons as it ages. , as was thought until a few years ago: in animals, for example rats and macaques, neurogenesis in adulthood has been demonstrated several times and there are also good clues in humans, given that some research suggests that in some brain areas it can form new neurons even after the age of 70. There are no certainties about this yet, but even if it doesn’t create new cells, the brain can certainly grow by continuing to learn, as long as we are alive.
To plasticity
Man is a very special animal. His childhood and adolescence are longer than that of everyone else, not only because it takes him longer to achieve independence and the ability to reproduce, but above all because of what happens in his head. The brain of a child in the first months and years of life is in a phase of tumultuous growth, so much so that it forms over a million new connections every second. A decisive period because, as Alfredo Berardelli, past president of the Italian Society of Neurology, explains, how much you eat in the first thousand days of life, for example, affects how the brain will function for the rest of your existence. Breastfeeding is fundamental and the mother must have a healthy diet because the milk contains all the necessary nutrients, but even after weaning, nutrition for the first 2-3 years of life remains essential: in this period many nervous connections are formed which decide like the child he will then be able to use his memory and learn, control his impulses and mood, plan activities and multitask. Childhood is also a phase in which the possibilities of enhancing cognitive abilities are at their maximum: brain abilities are developing thanks to the creation of new connections between neurons and also for this reason the quality of education in the early years is the basis for a healthy brain for a long time. Improving mental performance for a realistic goal even after and the idea that there is a privileged period for learning during childhood is outdated: brain cells continue to maintain a certain amount of plasticity well beyond adulthood, allowing anyone of being able to improve brain performance, at least in theory, in every moment of existence.
The great pruning of brain functions
Adolescence, however, is the other decisive moment for the brain, which again goes through a phase of profound change over a longer period of time than was supposed: according to the new definitions, adolescents are between 10 and 24 years old, but up to By the age of 30, the brain continues to develop and mature to a significant extent. The adult brain size is reached in early adolescence, when the growth in volume ends and the quantity of gray matter, which corresponds to the nerve cells, is maximum, while the white matter (the nerve connections) tends to increase later, as adults. What happens in the years of adolescence is a refinement of cognitive functions thanks above all to the so-called pruning, a real pruning of brain connections through which those no longer necessary are eliminated, so as to make the brain more agile, ready to learn and capable to adapt better and more quickly to situations thanks to the creation of new networks between neurons. In short, the brain goes back to being a sponge, like in young children, and for this reason the lifestyle and experiences lived in adolescence are decisive for better or for worse.
What happens to teenagers
In this period it is very important to have a healthy diet, do physical exercise, get enough sleep; It’s a shame that kids’ brains work against the way it’s done. In fact, the last part to mature is the prefrontal cortex, or the area responsible for reasoning, planning, decisions and impulse control; kids instead navigate the world by relying on the limbic system and the amygdala, areas that develop first and are associated with emotions and survival mechanisms such as the flight-or-fight reaction. Furthermore, the social part of the brain takes on particular importance, which makes adolescents inclined towards experiences together with their peers: excellent when you make new friends or spend a lot of time with your favorite sport teammates, a little less if you hang out with bad people. companies. The poor capacity for judgment due to the immaturity of the prefrontal cortex, which matures at different times from person to person and can take place until around the age of 30, leads to giving more importance to gratification than to the consequences of one’s behaviour: for this reason if one If you taste a substance of abuse and have a pleasant experience, it becomes easier to fall into an addiction. This is a period of critical brain remodeling in which, as the English neuropsychologist from the Southampton Children’s Hospital Angela Griffin explains in a study on brain changes in adolescents, the connections that develop the most are those between the hippocampus and the frontal cortex: in In this way we gradually become better at using memories and experiences to make decisions, reconciling emotions with the demands of external reality. To become good at this, experiences with peers are very important, as they are among the most crucial for the development of the adolescent brain: this is also why the possible effects of the social restrictions put in place during the pandemic are worrying, which are only now starting to be traced and which they seem to be able to have consequences on young people between 10 and 24 years old in much larger proportions compared to other age groups, precisely because of the decisive phase in which their brains find themselves. Ian Gotlib, of the Department of Psychology at Stanford University (USA), observed that after the pandemic, adolescents show not only greater mental distress, but also a thinner cerebral cortex, a greater volume of the amygdala and hippocampus and other characteristics compatible with a brain that has aged more quickly than it should. The implications are yet to be deciphered, but returning to frequent (good) company is certainly one of the recommendations to be put into practice to help the brains of very young people develop as best as possible.
Training increases cognitive reserve
Up to the age of 30, we explained, the brain learns, changes and grows. Then it starts to contract because we lose neurons, with a speed that increases significantly after the age of 60: the volume drops especially in the frontal areas, responsible for reasoning and emotional control, and in the hippocampus, involved in learning and memory processes. At the same time, the cerebral cortex thins because the cells, as they decrease, become thinner and have fewer connections between them, as also demonstrated by the reduction of white matter in old age; this, together with a decrease in the production of neurotransmitters through which neurons communicate, gradually slows down cognitive functions. This is certain, but it is not yet clear whether or not new neurons form in the adult brain: some researchers believe that it can happen even after the age of 70, at least according to the results of a Columbia University study on autopsies of people of various ages (it seems for that these are cells less capable of creating new connections).
Neurogenesi
Further investigations suggest that at least in adulthood, before becoming very old, neurogenesis exists and in the hippocampus, one of the areas where nerve stem cells have been identified, up to a hundred new neurons are created every day; other studies dampen hopes and research published in Nature has indicated 13 years as the limit beyond which new neurons are not added. The question is open, but there is agreement on the fact that the connections count more than the number of cells, which make the human brain very plastic and able to learn new skills even when elderly, albeit with greater effort. For this reason, it is never too late to train the brain, as Alfredo Berardelli observes: Even when elderly, brain performance can be improved. Of course, it is important to keep the brain busy throughout life to strengthen the network of brain connections: it creates a consistent cognitive reserve, so when some function fails due to the deterioration of the nerve cells it can be replaced by other neurons in the network. But it is never too late and all activities that stimulate the mind can be good as long as you are motivated and do them willingly but also choose something that really “turns it on” and is not a passive exercise: reading, hanging out with friends, visiting museums, creating opportunities to learn something new and something you like are all effective methods. Remembering that just as in our body we have many different muscles to strengthen through different training, so the brain has various abilities to exercise: memory, attention, concentration, language, logic, creativity, reasoning. Each one must be stimulated with different activities, which is also why there is no absolute best one, concludes the neurologist.
November 13, 2023 (modified November 13, 2023 | 08:10)
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