A new study conducted by Columbia University, published in the well-known journal Nature Communicationsoffers a fascinating new perspective on one of the most complex events in human neurobiology: the brain development throughout life. Analyzing the brains of 3,802 people from 0 to 90 yearsresearchers found that the brain topology, that is, the way in which they are organised neuronal connectionsvaries over time, crossing five distinct stages: the brain of children (0 to 9 years), adolescents (9 to 32 years), adults (32 to 66 years), early old age (66 to 83 years) and advanced old age (over 83 years). The transition from one phase to another would be guaranteed by real “turning point”specific moments in life (at 9, 32, 66 and 83 years) in which the brain architecture undergoes significant changesdefining the cognitive and emotional characteristics typical of each phase. These results they overturn classic theories of neurodevelopmentaccording to which brain development occurs in a linear and progressive manner throughout life, revealing a trajectory similar to a journey with intermediate stages.
Attention: the study on the turning points of the human brain does not mean that at the age of 32 one suddenly becomes an adult or that at 66 everyone enters old age. These are statistical values that approximately summarize a context of great individual variety, not to mention that terms such as “adolescent”, “adult” or “elderly” have important socio-cultural connotations that are not taken into consideration in this context. The important aspect of the study is the existence of distinct phases rather than the exact location of the border ages.
The 5 “transformations” of the brain during the course of life
That our brain changes over the course of life it’s an intuitive fact. And we have proof of this every time we ask ourselves questions like: how did I have such a vivid imagination as a child? Or when we look at an old photo and ask ourselves: did I really dress like this as a teenager? But how does this change actually happen? To answer this question, researchers at Columbia University collected and analyzed data from 3,802 subjects aged between 0 and 90 years, obtained through a technique called diffusion MRIwhich allows you to precisely map the connections between neurons. In this way, the researchers managed to reconstruct the neuronal topologyi.e. the map with which neuronal connections are organised, identifying five different “brain architectures”each of which is typical of a specific phase of life.
From or to 9 years: a construction phase
In the first years of life (from 0 to 9 years), our brain is a real “open construction site”which he uses all his energy to organize and consolidate the first neural networks still immature. During this phase, which marks the childhood periodthe brain is not yet capable of operating as a fully integrated global network, but functions mostly through small local networks, still in the process of coordinating with each other.
From 9 to 32 years: the peak of adolescence
Around nine, however, occurs first turning point, a moment in which the brain structure changes dramatically, marking the transition to stage of adolescence. During this period, brain connections progressively reach maximum efficiencyallowing different areas of the brain to communicate quickly between them, reaching the peak functionality around the age of thirtyage at which the brain is at its peak cognitive performance.
From 32 to 66: we become adults
Around the 32 years oldthe brain faces the deepest reorganization of its connectionswhich marks the transition from adolescence to the adult phase, characterized by a structural and functional stability which lasts for about thirty years.
From 66 to 83: we enter old age
AND at 66 years old that the brain goes through the next transformation, which marks the entry into the early old age, a phase in which connectivity between different brain areas begins to progressively reduceaccompanied by a decrease in cognitive functions.
Over 83: the final change
The latest change in neural architecture it would happen at 83 years oldphase in which the brain further reduces the efficiency of its connections, marking the entrance to advanced old age.
Why this study is important
The brain development has always been imagined as a continuous processcharacterized by a slow and progressive change of neural connectionsproceeding without interruption from birth to old age. In short, a bit like a high-speed train that runs without stops from Naples to Milan.
This new study, however, shows that brain development it doesn’t go entirely in a straight line, but it goes through limited periods of intense structural revolutions. Four distinct moments (9, 32, 66 and 83 years old) in which the configuration of neural connections changes drasticallymarking the transition between the main ones stages of life: childhood, adolescence, adulthood and old age. In short, a bit like traveling by train from Naples to Milan, but this time stopping at intermediate stations, changing the train from time to time.
These “moments of revolution” of brain networks not only do they correlate with changes in our cognitive and emotional functions (which, it should be noted, were not measured in this study), but also often coincide with the onset of neurodevelopmental and neurodegenerative pathologieswhich tend to make their debut precisely in transition phases, such as the transition from childhood to adolescence or the beginning of old age.
Understanding how the brain change its wiring and what influences the correct transition from one phase to another it could represent the first step in improving our knowledge of these pathologies and, who knows, maybe paving the way to new treatments capable of countering them.
