Quando o cérebro cresce e diminui

Have you noticed how our abilities change over the course of our lives? What you probably don't know, however, is that much of it has to do with the rate of growth and maturation of different brain structures. A study conducted by 200 researchers from countries across the globe analyzed 123,984 magnetic resonance images in order to map the evolution of the most complex organ in our body.

The study plotted an unprecedentedly detailed and precise timeline of how a healthy human brain develops, from gestation to the end of life. The result is a graph with curves resembling those found in growth charts, which show the adequate height and weight for children of different ages. The graph created by the new study defines the milestones in brain development for the different stages of life.

Por volta da metade da gestação, Around the mid-gestation period, the brain has reached only 10% of its final size. And yet, just 3 years after that, it will have reached 80% of its final size. In other words, during the first 1000 days of life, our brain grows at an incredibly fast rate: This fact supports the idea that this stage of life – from gestation to 2 years of age – is the most important period for a person's physical and mental integrity.

The brain continues to grow until the person is roughly 30 years of age. From that time on, it slowly decreases in size. But the parts that make up the brain don't grow or decrease in size at the same rate, and this affects certain behavioral patterns that we adopt at different times in life.

Cortical gray matter, also called the cortex, sees rapid growth after the second half of the gestation period and reaches its peak at around 6 years of age. It is responsible for functions like attention, memory, language, planning and it contributes to motor control and environmental perception. If we take a 6-year-old child, we can observe that basic functions mature at a much earlier age.

So let's take a 1-month-old baby. What is he doing? When he's 3 months old, he can hold up his neck.

So these are basic functions. At 6 months, he can sit up, with help. At around 6 or 7 years of age, the child can feed herself, hold a pencil, write, her attention has improved considerably in comparison to a younger child, she can sit in place in a classroom and pay attention, in a 20- or 30-minute-long class.

Her mathematical abilities develop at a fast rate. Subcortical gray matter, on the other hand, reaches its maximum size at roughly the age of 14. Formed by groups of neurons located in the innermost regions of the brain, it plays a role in the control of emotions, in the regulation of body temperature, hunger, as well as in our sleep-wake cycle.

A gente viu que tem um pico de maturação We observed a peak of subcortical gray matter maturation around adolescence and we think there's a spike in social interactions during adolescence. So, usual adolescent behavior, the need to please their peers, for instance becomes increasingly important. We know that some abilities aren't completely developed at that stage, such as decision-making, impulse control.

These functions require more time to fully develop. White matter is responsible for the communication between the cortex and subcortical gray matter. It reaches its maximum size at 30 years of age.

Our brain continues to develop even after turning 30, because these functions – decision-making, behavior control, reward circuits – are extremely complex for our brains to handle and they require more time, more experience until they become fully consolidated. Each of these brain components start diminishing in size at a certain age, but at the age of 40 the shrinking of all three components becomes more evident. The hollow spaces resulting from the shrinking of these components a clear, colorless, sterile liquid, which protects the organ against impacts and infections.

We all have a certain – we all start to forget things, our memory isn't as good as it used to be when we were adolescents or adults, but that is to be expected. And the study can clearly show us that, in individuals with Alzheimer's or some form of cognitive impairment, there is a certain point in their life in which brain development stops being healthy and becomes pathological, meaning there is a rapid loss, which is associated with cognitive alterations, especially memory loss. But adoption of the brain development graph by doctors still has a long way to go.

Even if it shows the expected sizes for each age group, it still can't be used to verify whether a person's brain is developing in accordance with standards. But the future lies in the deeper research: the amount of information used in the creation of the curves must increase, and must include more data, basing it on people of different ethnicities, socio-economic statuses and regions of the planet.