Women who are obese have a higher risk of giving birth to children who have autism. Mauro Costa-Mattioli, a neuroscientist at Baylor College of Medicine, and colleagues are the first to discover that the lack of a gut bacterium is a cause of the symptoms of autism.
Sixty female mice were fed a diet that was the equivalent of eating three fast food meals per day. The mice gave birth to offspring that had a much higher rate of displaying symptoms that are consistent with autism. The researchers used ribosomal RNA gene sequencing to identify the microbes that lived in the guts of the autistic mice. The Lactobacillus reuteri bacterium was reduced more than nine-fold in the guts of mice born with autism.
The researchers developed three strategies to “cure” the symptoms of autistic mice that were caused by a lack of one bacterium. The autistic mice were paired with normal mice and regained the normal gut bacterium Lactobacillus reuteri by eating the feces of normal mice. The normal gut bacterial group was restored in autistic mice through fecal-transplant. The autistic mice were given human breast milk containing the missing bacterium.
The study showed that an increase in the number of Lactobacillus reuteri reduced the social avoidance seen in autism but not the anxiety. The bacterium also increased the levels of oxytocin produced. The bacteria were found to restore the lack of synaptic function in the reward circuitry of the brain.
The study is the first to show that a gut bacterium may play a crucial role in autism. The rate of obesity in women in the United States is now 40 percent. No effort has been successful in decreasing obesity in men or women.
Autism rates have increased as obesity rates have increased in women. One of the problems with obesity is the lack of delivery of the bacterium Lactobacillus reuteri in blood or breast milk. The new research will not cure obesity but it offers a much easier method of dealing with the symptoms of autism caused by obesity.