Too much sugar in childhood could cause obesity and ADHD in adults

Children who consume too much sugar could be at greater risk of becoming obese, hyperactive and cognitively impaired as adults.

This is according to the results of a new study led by Queensland University of Technology (QUT) academics and published in the journal Frontiers in Neuroscience.

A trial using mice has shown that a diet high in sugar from childhood may lead to significant weight gain, persistent hyperactivity and learning impairments in adulthood. This has particular relevance to people on ‘western’ diets, many of whom consume four times more sugar than recommended by the World Health Organisation (WHO).

Impulsive behaviours may be one of the effects

One of the lead authors, QUT neuroscientist Professor Selena Bartlett, said children, adolescents and adults in more than 60 countries – including Australia – tend to consume 100g-plus of sugar each day, versus the WHO’s suggested 25g per day.

“Recent evidence shows obesity and impulsive behaviours caused by poor dietary habits lead to further overconsumption of processed food and beverages. But the long-term effects on cognitive processes and hyperactivity from sugar overconsumption, beginning at adolescence, are not known,” said Professor Bartlett.

“Our study found long-term sugar consumption (a 12-week period with the mice which started the trial at five weeks of age) at a level that significantly boosts weight gain, elicits an abnormal and excessive stimulation of the nervous system in response to novelty.

“It also alters both episodic and spatial memory. These results are like those reported in attention deficit and hyperactivity disorders.

Similar to the brain circuitry driving drug abuse

Professor Bartlett said while the concept of ‘sugar addiction’ and the classification of sugar as a substance of abuse were still being debated, there is increasing evidence of overlap in the brain circuitry and molecular signalling pathways involved in sugar consumption and drug abuse.

“People consume sugar and food to regulate energy balance, but also for pleasure and comfort. This hedonistic desire for palatable food is reward-driven and overeating can impact upon and even override our ability to regulate,” she explained.

Co-lead author, Dr Arnauld Belmer, added that while overall sugar consumption has dropped since the mid-1990s, obesity rates have climbed.

“This rise in obesity rates could result from a delayed effect of excess sugar, suggesting that adult obesity may be driven by high sugar intake over a life span,” Dr Belmer said.