Low glycemic index diet reduces symptoms of autism in mice

June 9, 2015, Salk Institute
The brains of mice fed a high glycemic index diet have greater numbers of activated immune cells (shown in red and green) called microglia. Credit: Antonio Currais/Salk Institute

Bread, cereal and other sugary processed foods cause rapid spikes and subsequent crashes in blood sugar. In contrast, diets made up of vegetables, fruits and whole grains are healthier, in part because they take longer to digest and keep us more even-keeled.

New research in a mouse model of autism showed that such low diets, similar to the plans that people with diabetes follow to keep their in check, reduced symptoms of the disorder in mice. Although preliminary and not yet tested in humans, the findings, published June 9 in the journal Molecular Psychiatry, might offer clues to understanding one potential cause of autism.

The number of people diagnosed with autism—a spectrum of disorders characterized by social avoidance, repetitive behaviors and difficulty communicating—has risen dramatically over the past two decades for reasons that are unclear.

More people may be diagnosed due to a broader definition of autism and better efforts in diagnosis, but a true increase in the disorder cannot be ruled out, according to the U.S. Centers for Disease Control. Lifestyle change is one potential factor out of many possible causes of autism.

'One thing that's driving a lot of general physiological changes in people is changes in the diet,' says the study's corresponding author Pamela Maher, a senior staff scientist in the laboratory of professor David Schubert at the Salk Institute for Biological Studies.

In the new study, the Salk scientists used a mouse model of autism—an inbred strain of mouse previously found to display autism-like symptoms—to ask whether lowering the level of dicarbonyl methylglyoxal (a common byproduct of sugar metabolism) could alleviate symptoms of autism in the animals.

Pam Maher, Senior Staff Scientist at the Salk Institute. Credit: Salk Institute

The scientists fed either the high or low glycemic index diet and kept their offspring on the same diet after birth and weaning, because their brains are still forming crucial connections.

The researchers then used a battery of behavioral and biochemical tests to study the mice after weaning. The two groups of animals consumed the same number of calories and were identical in weight. But mice that ate a high-glycemic index diet showed all of the expected behavioral symptoms of autism. Their social interactions were impaired, they repeated actions that served no apparent purpose, and they groomed extensively.

The mouse models of autism on a normal lab diet (with a medium glycemic index) are already known to generate fewer new neurons, and some of their existing cells and neuronal connections are abnormal compared with those of normal mice.

Intriguingly, in the new study, the brains of mice modeling autism that were fed the high-glycemic index diet had drastically less doublecortin, a protein indicator of newly developing neurons, compared to predisposed mice on the low-glycemic index diet. The deficiency was especially obvious in a part of the brain that controls memory.

In addition, the brains of the high-glycemic index diet mice appeared to have greater numbers of activated microglia, the resident immune cells of the brain. Their brains also expressed more genes associated with inflammation, compared to the mice fed the diet.

Other studies of human mothers and their children with autism have implicated the activation of the immune system. For the most part, these studies have focused on infection, which causes a bout of inflammation—as opposed to a high-glycemic index diet, which causes chronic, low-level inflammation, Maher says.

The new study found that the diet might directly influence the ecosystem of bacteria in the gut. More complex starches are broken down by bacteria that live in the lower part of the gut, the large intestine. The group saw some evidence of that in the blood, detecting metabolites that could only have come from the gut in larger amounts in the animals fed the high-glycemic index diet.

'We were really surprised when we found molecules in the blood that others had reported could only be generated by gut bacteria,' Maher says. 'There were big differences in some of these compounds between the two diets.'

The group plans to analyze the gut bacteria, and its potential link with features of autism, more directly. They also hope to better understand the role of inflammation in the ability to generate new neurons.

Lastly, they plan to vary the timing of exposure to the various diets in the of , by, for example, giving pregnant a high-glycemic index diet and then keeping their pups on a normal .

Explore further: Healthy eaters, ignore glycemic index: Clinical trial shows no beneficial effects on heart disease, diabetes risk

Related Stories

Healthy eaters, ignore glycemic index: Clinical trial shows no beneficial effects on heart disease, diabetes risk

December 16, 2014
Good news for people who are already following a diet rich in fruits, vegetables and whole grains, and low in sweets: New research suggests these heart-healthy eaters don't need to worry about choosing low glycemic index ...

High-fat diet alters behavior and produces signs of brain inflammation

March 26, 2015
Can the consumption of fatty foods change your behavior and your brain?

Study shows less aggressive behavior toward strangers in autism spectrum disorder model

February 25, 2015
While aggression toward caregivers and peers is a challenge faced by many individuals and families dealing with autism, there has been much speculation in the media over the possibility of generally heightened aggression ...

Team finds differences in RORA levels in brain may contribute to autism sex bias

May 27, 2015
George Washington University (GW) researcher Valerie Hu, Ph.D., has found an important sex-dependent difference in the level of RORA protein in brain tissues of males and females. Specifically, females without autism have ...

Recommended for you

Autism risk determined by health of mom's gut, research reveals

July 18, 2018
The risk of developing autism-spectrum disorders is determined by the mother's microbiome—the collection of microorganisms that naturally live inside us—during pregnancy, new research from the University of Virginia School ...

Brain scans yield more clues to autism

July 17, 2018
(HealthDay)—Children with autism show abnormalities in a deep brain circuit that typically makes socializing enjoyable, a new study finds.

Autism spectrum disorder linked to shape of brain's cerebellum

July 11, 2018
Structural differences in the cerebellum may be linked to some aspects of autism spectrum disorder, according to a neuroimaging study from Columbia University Irving Medical Center (CUIMC).

Autistic people do want to socialize, they may just show it differently

June 28, 2018
A new paper led by the University of Virginia and just published in the journal Behavioral and Brain Sciences is pushing back hard on the notion that people with autism are not interested in socializing.

Researchers discover promising treatment for genetic form of autism spectrum disorder

June 26, 2018
It may soon be possible to reverse a genetic form of autism spectrum disorder (ASD) by using drugs initially developed to treat cancer.

CRISPR editing reduces repetitive behavior in mice with a form of autism

June 25, 2018
Scientists have used CRISPR-Cas9 gene editing to lessen some autism symptoms in mice with a form of fragile X syndrome, the most common known single-gene cause of autism spectrum disorder.

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

EnricM
not rated yet Jun 10, 2015
Good news for mice!

They will finally get rid of this plague of mouse semi-autism. I assume it will be worth the price of having to boil alive, electrocute, torch and catapult so many mice (not to count the odd football and cricket match using mice as a ball).

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.