Depression, a disorder that can affect us at any time in our lives, shows its most complex face in the transition from childhood to adolescence, the so-called pre-adolescence, a period of intense changes and challenges. This stage of life, marked by a significant transformation both physically and emotionally, is also a critical moment in brain development, which can be altered if you suffer from mental disorders such as depression.

Understanding the changes that occur in the preadolescent brain, and how depression can influence them, is essential to being able to effectively address this disorder. During preadolescence, the brain not only grows in size, but also undergoes a substantial reorganization in its neural connections, a fundamental restructuring for the development of cognitive (attention, memory, decision making, social learning, etc.) and emotional skills. .

However, when depression intervenes, it can disrupt this delicate process, affecting key areas of the brain responsible for the emotional and cognitive processes indicated above. These changes not only have an immediate impact on well-being during the time of depression: they can also be related to mental health problems in adulthood.

Brain development with age

The human brain develops continuously from conception to middle age. But the period of greatest growth and change occurs during childhood and adolescence.

The brain is generally considered to reach full maturity between the ages of 25 and 30. However, some parts of the brain, such as the prefrontal cortex, continue to develop until the age of 40.

In preadolescence the brain is not yet fully formed . Due to the changes that occur in this period, our thinking organ becomes highly susceptible both to what surrounds us and our inner world and to the development of neurological disorders. And as it is often said colloquially, we may be more prone to getting our wires crossed, that is, to having our brain connectivity change.

Depression and major depressive disorder

Let us not forget that the most common among all mental disorders is depression, considered by its numbers to be a true pandemic . According to the World Health Organization ( WHO ), 280 million people around the world suffered from depression in 2020, with an increase of 25% compared to 2019, being one of the main causes of disability.

The prevalence of depression is higher in women than in men, and increases with age . Thus, approximately 2.5% of children and adolescents suffer from depression. In young adults the percentage increases to 5%, rises to 7% in middle-aged adults, and reaches 10% among older people.

Depression is characterized by a depressed state of mind, despite the redundancy . That is, we lose interest or the pleasure of enjoying the activities that we liked most, there are changes in appetite or weight, we have problems both concentrating and sleeping, we become fatigued, we suffer feelings of guilt or uselessness and we can become to habitually think about death and suicide.

When things get worse, major depressive disorder occurs , also known as clinical depression. It occurs when our mood causes persistent feelings of sadness and loss of interest in practically everything, including our favorite activities, and it undoubtedly affects the way we think, feel, and act. In that case, do not hesitate to seek professional help.

Preadolescence, major depressive disorder and connectivity

While there have been numerous studies identifying abnormal connectivity associated with mental disorders in adults, considerably less is known about the biological basis of depressive disorder at younger ages.

The “gold standard” for diagnosis is the Diagnostic and Statistical Manual of Mental Disorders ( DSM ). But the studies carried out so far consider its reliability and consistency as “ questionable ” (from a statistical point of view) when two or more evaluators rate the answers.

In order to detect the possible existence of changes in brain connectivity during its development before adulthood, as well as its relationship with major depressive disorder, a very interesting scientific study has just been presented in which data have been related neuroimaging with cognitive tests in 1,429 healthy participants and 353 participants diagnosed with depression, all between 9 and 10 years of age.

By applying a new and powerful computational algorithm to the brain scans of each subject, the researchers obtained 98 regions of interest and calculated the functional connectivity between them with another new , also very powerful, algorithm.

Results showed disrupted patterns of functional connectivity in preadolescents with major depressive disorder compared to the control group. These alterations were observed both at the level of the whole brain and within three large neural networks with specific functions: (i) the network that acts on processes such as self-reflection, memory and future planning (the default network); (ii) the network that functions when we make decisions, solve problems and that participates in impulse control (the central execution network), and (iii) the network that detects what we perceive from our environment, filters it and makes us respond to the unexpected (the relevance network).

Alterations in these three neural networks could have significant consequences in preadolescents. Thus, the alteration of the default network implies that preadolescents could experience difficulties in introspection and understanding their own mental states and emotions. This could lead to self-esteem problems and difficulties in planning future tasks or events. Furthermore, alteration in this network could affect the ability to remember past experiences and learn from them, which is essential during preadolescence, a key stage for the development of personal identity.

If the central execution network is altered , preteens could have difficulty making rational decisions and critical thinking, in addition to becoming more impulsive or, on the contrary, indecisive.

And if the relevance network is also disrupted , preadolescents could become less sensitive to the stimuli in their environment or, on the contrary, feel overwhelmed by the information that comes to them and manifest difficulties concentrating and inadequate responses also in interaction situations. social.

In conclusion, and given that there are changes in brain activity and connectivity induced by major depressive disorders at very early ages, knowledge of them is very useful to identify and treat depression as soon as possible, in order to avoid negative consequences to long term and promote better mental health in adulthood.

Author Bio: Francisco José Esteban Ruiz is a Full Professor of Cellular Biology at the University of Jaén