A recent study found that people with diets high in fat and sugar had worse spatial memory than those who ate these foods less often. This may not be much of a surprise. We’ve long known that unhealthy eating can contribute to the onset of cognitive decline. What may come as a surprise is that the people in this study were between the ages of 18 and 38.
Do we need to start protecting our brains from cognitive decline while we’re still young? “Definitely,” says lead author of the study, Dominic Tran, a cognitive neuroscientist at the University of Sydney who focuses on learning, memory, and cognition.
Fat, Sugar, and Impaired Brain Function
For the study, college students were asked to navigate a virtual maze to locate a treasure chest. In order to find the treasure chest, the subjects had to estimate distance and direction and remember the location of landmarks. They did this six times; in a seventh and final trial, researchers removed the treasure chest from the maze, and the students had to find its location by memory.
The subjects with diets higher in saturated fat and refined sugar were worse at remembering how to find the location of the treasure chest. The results held even after the researchers controlled for body mass index, suggesting that the difference in cognitive function was related to the types of food being eaten (fat and sugar) and not to body weight.
Tran and colleagues point out that the study was small and did not involve altering the diets of the subjects and comparing the differences before and after. Still, the study adds to a growing body of evidence that fat and sugar can contribute to impaired brain function, even in young people.
“Over the past 10 years or so, there has been a lot of research investigating the impact of high-fat/high-sugar diets on cognitive functioning, and the results are quite worrying,” says Tran.
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Cognitive Health
Most of us don’t begin thinking about our cognitive health until we start having achy joints, or worse yet, begin to have trouble remembering words. But Francesa Farina urges us to start thinking about brain health while we’re still young.
Farina is a neuroscientist with the Global Brain Health Institute, and much of her work centers on the detection of risk factors for dementia in young adulthood and midlife.
“I think we still have a perception of Alzheimer's and dementias as diseases of old age,” she says. “But more and more, the science is telling us that the brain changes that underlie these diseases are happening 10, 20 years before that.” That means we need to start paying attention to our risk factors while we’re still young.
Farina points out that some of the lifestyle factors that can increase the risk of dementia, such as obesity, hypertension, and diabetes, are becoming more frequent in young people. The good news is that lifestyle changes now can reduce the risk of cognitive problems down the road.
It might be hard to convince young people that they need to make an effort now to reduce the risk of getting a disease they don’t expect to get until they’re older. But Tran’s research suggested that the effects of a poor diet can be felt right away. Perhaps we need a change in messaging. Farina recommends framing the discussion as “brain health” rather than dementia. And ensuring good brain health is a lifetime project. In fact, Farina says we need to consider these risk factors even in children.
Not Too Late to Reduce Fat and Sugar
Can cognitive impairments like the ones in Tran’s study be reversed? Tran thinks it’s possible.
“We are very hopeful that improvements to diet quality can improve cognitive deficits associated with unhealthy diets,” he says. His team plans to study that next. Meanwhile, his advice is to eat a healthy, balanced diet with reduced saturated fat and sugar.
“You don’t have to cut these out completely,” he says, “but eating them in moderation, infrequently, should be the goal.”
This article is not offering medical advice and should be used for informational purposes only.
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Article Sources
Our writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles, and our editors review for scientific accuracy and editorial standards. Review the sources used below for this article:
International Journal of Obesity. Consumption of a diet high in fat and sugar is associated with worse spatial navigation ability in a virtual environment
Neuroscience & Biobehavioral Reviews. The impact of saturated fat, added sugar and their combination on human hippocampal integrity and function: A systematic review and meta-analysis
Avery Hurt is a freelance science journalist. In addition to writing for Discover, she writes regularly for a variety of outlets, both print and online, including National Geographic, Science News Explores, Medscape, and WebMD. She’s the author of Bullet With Your Name on It: What You Will Probably Die From and What You Can Do About It, Clerisy Press 2007, as well as several books for young readers. Avery got her start in journalism while attending university, writing for the school newspaper and editing the student non-fiction magazine. Though she writes about all areas of science, she is particularly interested in neuroscience, the science of consciousness, and AI–interests she developed while earning a degree in philosophy.
