Too much sugar can mess up cognition in kids

Adolescence is also a time of newly found independence, including food choices.

By Amy Reichel

Published: Wed 26 Oct 2016, 10:00 PM

Last updated: Thu 27 Oct 2016, 12:06 AM

The rate of obesity is increasing worldwide and the increase has been particularly dramatic in young people. Youngsters are the greatest consumers of high-energy, sugary and fatladen "junk" foods and sweetened drinks. The heightened metabolism and rapid growth during puberty can protect against obesity. However, easy access to cheap junk foods and increasingly sedentary lifestyles outweighs the protection from growth spurts. Diets high in refined sugar and saturated fat not only contribute to weight gain and associated health issues, but also have a profoundly detrimental impact on brain function. It is known that excessive consumption of junk foods dam-age areas of the brain essential for learning and memory processes. Neurons in brain regions, including the hippocampus, that encodes memories, no longer work efficiently, leading to poorer learning.
This is of great concern as adolescence is a critical formative period for learning about the world. Adolescence is also a time of newly found independence, including food choices.
Inflammation in the brain can contribute to cognitive decline and dementia. The negative effects of obesity on the brain have been observed in young people too. Obese adolescents per-formed worse at maths, spelling and mental flexibility than healthy-weight adolescents. Structural brain scans revealed that obese teenagers had smaller hippocampi. This provides evidence that excessive body fat impacts the brain's learning centre.
The teenage brain undergoes major developmental changes in terms of structure and function. Adolescence is a period of increased neuroplasticity due to the dramatic changes in connectivity within brain regions. Brain-imaging studies show that the prefrontal cortex doesn't fully mature until the early 20s. A major role of the prefrontal cortex is performing executive functions. This term encapsulates behavioural control, attention and decision making.
Poor regulation of the prefrontal cortex during adolescence can explain the increased risk taking behaviours in teenagers, including dangerous driving, drug use and binge drinking.
The risky behaviours teenagers engage in are often immediately rewarding. The brain's reward system releases the neurotransmitter dopamine when stimulated by pleasurable events, in-creasing the drive to carry out these activities. Teenagers are particularly drawn to rewards, including eating tasty foods high in fat and sugar. The adolescent reward system is sensitive to stimulation and may be permanently altered by over-activation during this period. Combined with the reduced ability to resist rewarding behaviours, it is not surprising that teenagers prefer to eat foods that are easy to obtain and immediately gratifying, even in the face of health advice to the contrary.
Changes in the brain caused by over-consumption of sugary foods during adolescence can manifest in later life as difficulties in experiencing reward. Excessive consumption of junk foods during adolescence could derail nor-mal brain maturation processes. This may alter normal development trajectories, leading to enduring behavioural predispositions - in this case, the habit of consuming fatty and sugar foods, leading to obesity. Fortunately, the in-creased plasticity of the adolescent brain means that young people may be more responsive to change. Opportunities to identify and intervene in high-risk youths may avert destructive negative behavioural spirals that may originate in adolescence. This can en-courage life-long healthy habits.-
The writer is a lecturer, ARC DE-CRA, RMIT University, Australia
The Conversation

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