From: olivercranglejr@gmail.com   
      
   Gut Bacteria May Play a Role in Autism   
   Evidence is mounting that intestinal microbes exacerbate or perhaps even cause   
   some of autism's symptoms   
   Aug 14, 2014 |By Melinda Wenner Moyer   
   **   
   bacteria   
      
   Bacteroides fragilis    
   Credit: CNRI/SCIENCE SOURCE   
   Autism is primarily a disorder of the brain, but research suggests that as   
   many as nine out of 10 individuals with the condition also suffer from   
   gastrointestinal problems such as inflammatory bowel disease and "leaky gut."   
   The latter condition occurs    
   when the intestines become excessively permeable and leak their contents into   
   the bloodstream. Scientists have long wondered whether the composition of   
   bacteria in the intestines, known as the gut microbiome, might be abnormal in   
   people with autism and    
   drive some of these symptoms. Now a spate of new studies supports this notion   
   and suggests that restoring proper microbial balance could alleviate some of   
   the disorder's behavioral symptoms.   
   At the annual meeting of the American Society for Microbiology held in May in   
   Boston, researchers at Arizona State University reported the results of an   
   experiment in which they measured the levels of various microbial by-products   
   in the feces of    
   children with autism and compared them with those found in healthy children.   
   The levels of 50 of these substances, they found, significantly differed   
   between the two groups. And in a 2013 study published in PLOS ONE, Italian   
   researchers reported that,    
   compared with healthy kids, those with autism had altered levels of several   
   intestinal bacterial species, including fewer Bifidobacterium, a group known   
   to promote good intestinal health.   
   One open question is whether these microbial differences drive the development   
   of the condition or are instead a consequence of it. A study published in   
   December 2013 in Cell supports the former idea. When researchers at the   
   California Institute of    
   Technology incited autismlike symptoms in mice using an established paradigm   
   that involved infecting their mothers with a viruslike molecule during   
   pregnancy, they found that after birth, the mice had altered gut bacteria   
   compared with healthy mice. By    
   treating the sick rodents with a health-promoting bacterium called Bacteroides   
   fragilis, the researchers were able to attenuate some, but not all, of their   
   behavioral symptoms. The treated mice had less anxious and stereotyped   
   behaviors and became more    
   vocally communicative.   
   Researchers do not yet know how exactly gut bacteria might influence behavior,   
   but one hypothesis is that a leaky gut may allow substances to pass into the   
   bloodstream that harm the brain. In the mouse study, the probiotic may have   
   helped reshape the    
   microbial ecosystem and made the intestines more robust, preventing the   
   leakage of such substances, says co-author Elaine Y. Hsiao, a microbiologist   
   at Caltech.   
   So could autism one day be treated with drugs designed to restore a healthy   
   microbial balance? Perhaps, but autism is the result of a "complex interplay   
   of genetic and environmental factors," explains Manya Angley, an autism   
   researcher at the University    
   of South Australia, so the solution may not be that simple. Caltech biologist   
   Sarkis K. Mazmanian, co-author of the mouse study, agrees. "Many more years of   
   work will be needed before we are confident that gut bacteria impact autism   
   and whether    
   probiotics are a viable treatment," he says.   
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   http://www.scientificamerican.com/article/gut-bacteria-may-play-   
   -role-in-autism/   
      
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