How junk food can and does shape the developing brain of teens

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January 12, 2020-4: 00 am


How junk food can and does shape the developing brain of teens

Amy Reichelt

BrainsCAN Research Fellow at the School of medicine and dentistry, University of Western


The adolescent brain has strong urges towards the reward, a low behavioral control and a great ability to be shaped by the experience. This is often manifested by a difficulty to resist junk food, high calorie.

Obesity is increasing everywhere on the planet, especially in children and adolescents. In 2019, there are over 150 million obese children in the world. They have an increased risk of heart disease, cancer and type 2 diabetes.

Adolescents who are obese are likely to remain so in adulthood. If the current trend continues, 70 percent of adults 40 years of age could have an overweight or obese by 2040.

I am a neuroscientist, and my research focuses on how power changes the brain. I want to understand how poor eating habits affect the development of the brain, and also why the young people of today are so prone to obesity.

Teenagers are the biggest consumers of junk food rich in calories. During puberty, many children have an insatiable appetite, because rapid growth requires a lot of energy. A fast metabolism and growth spurts offer, to a certain extent, a protection against obesity. But excessive consumption of junk food, high calorie, and a sedentary lifestyle can counterbalance any protection metabolic.

The brain young person is vulnerable

Adolescence is a pivotal period for the development of the brain. Adolescence coincides with a new self-advocacy and independence that enables you to make food choices personal.

During adolescence, the connections between the different regions of the brain and the individual neurons are in a process of refinement and strengthening. The adolescent brain is malleable because of a “neuroplasticity” increased.

This means that the brain is very receptive to reshaping by the environment, which includes the power supply. These changes may remain programmed once the development is completed. The adolescent brain is so vulnerable to the changes induced by the diet, and these changes can last throughout his life.

Resist the junk food is not easy

Neuroscientists use functional brain imaging to examine how the brain reacts to events. Brain scans show that the prefrontal cortex – a key area of the brain to control behavioural and decision – making- does not reach full maturity until the beginning of the twenties.

The prefrontal cortex controls impulses triggered by what surrounds us and helps to resist it. For teenagers, it can be especially difficult to remember to swallow a whole bag of candy or buy junk food.

An insatiable need for rewards

In contrast to the prefrontal cortex remained immature, the reward system of the brain mesolimbic dopamine system – is fully developed at a much younger age.

Teenagers are especially attracted by the rewards, such as sugary foods and rich in calories. This is caused by an increased number of dopamine receptors in the brain as a teenager, so the feeling of reward can be exacerbated. The stimulation common of the reward circuit leads to adaptations of brain sustainable.

During adolescence, these changes can trigger transformations to the long-term in the balance of chemicals in the brain.

All in all, the adolescent brain has a huge desire for reward, a low behavioral control and a propensity to be influenced by the experience.

This is manifested by a difficulty to resist the behavior rewarding. It is therefore not surprising that teens would prefer to eat foods that are easy to get and make quickly a sense of reward, and this, even if they know that it’s bad for the health. But what are the long-term consequences for the brain ?

Transcranial magnetic Stimulation

Studies of functional imaging shows the brain activity during tasks, or viewing images of food. The brain circuitry of food reward are more active in obese adolescents than among those who have a normal weight.

It is interesting to note that there is also an activity lower in the prefrontal cortex. Thus, obesity can both increase the activation of the reward system and reduce brain activity in centers that control the desire to eat.

However, weight loss in adolescents restores the levels of activity in the prefrontal cortex. The prefrontal cortex is therefore a key area of the brain to control food intake, and the change in diet increases the activity in brain regions responsible for self-control.

Transcranial magnetic stimulation (TMS), which allows scientists to change the brain activity in the prefrontal cortex, may change the regulatory inhibitory feeding behavior. Treatment with SMT repeated could constitute a new therapy to restore the cognitive control of food, which would lead to a weight-loss sustainable.

Physical exercise increases the brain’s plasticity

The excessive consumption of junk food during adolescence may alter brain development and lead to poor eating habits that are sustainable. But, like a muscle, the brain can be exercised to improve the control.

The great plasticity of the brain during adolescence makes it more receptive to life style changes. The physical exercise stimulates the brain plasticity, helping to put in place new healthy habits. By understanding how obesity alters the brain, you can have tracks of intervention.

Functional brain imaging adds a new layer of information that enables clinicians to identify individuals at risk and to track changes in the brain during changes of diet and way of life.

Furthermore, the SMT may be a novel therapeutic approach to improve the recalibration of the young brain to prevent transformations that will remain in adulthood.

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This text first appeared on the website of the franco-canadian of The Conversation. Reproduced with permission.

Comment la malbouffe façonne le cerveau en développement des ados

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