From: olivercranglejr@gmail.com   
      
   14 December 2010   
   Diet shown to trigger mental illness   
   by Kate Melville   
   Changes in diet have previously been linked to a reduction of abnormal   
   behaviors in mentally ill animals and people, but a new Purdue University   
   study shows that diet can also trigger the onset of mental illness in the   
   first place.   
      
   In the experiment, mice were fed a diet high in sugar and tryptophan (an   
   essential amino acid) that was expected to reduce abnormal hair-pulling.   
   Instead, mice that were already ill worsened their hair-pulling behavior and   
   the seemingly healthy mice    
   developed the same abnormal behavior.   
      
   "This strain of mouse is predisposed to being either a scratcher or a   
   hair-puller. Giving them this diet brought out those predispositions," said   
   study author Joseph Garner, whose results were published in Nutritional   
   Neuroscience. "They're like    
   genetically at-risk people."   
      
   Garner studies trichotillomania, an impulse-control disorder in which people   
   pull out their hair. The disorder, which disproportionately occurs in women,   
   is thought to affect between 2 - 4 percent of the population.   
      
   Mice that barber (pull their hair out) have been shown to have low levels of   
   serotonin activity in the brain. Serotonin is known to affect mood and   
   impulses. Garner hypothesized that increasing serotonin activity in the brain   
   might cure or reduce    
   barbering and possibly trichotillomania.   
      
      
   Serotonin is manufactured in the brain from the amino acid tryptophan, which   
   is consumed in food. The problem is that tryptophan often doesn't make it   
   across the barrier between blood and the brain because other amino acids can   
   get through more easily    
   and "block the door" for tryptophan.   
      
   Garner modified a mouse diet to increase simple carbohydrates, or sugars, and   
   tryptophan. The sugars trigger a release of insulin, which causes muscles to   
   absorb those other amino acids and gives tryptophan a chance to make it to the   
   brain. Using eight    
   times as much sugar and four times as much tryptophan, Garner observed a   
   doubling of serotonin activity in the brain. But the mice did not get better.   
   "We put them on this diet, and it made them much, much worse," Garner said.   
      
   A second experiment divided the mice into three groups: those that were   
   seemingly normal, others that had some hair loss due to barbering and a group   
   that had severe hair loss. All the mice soon got worse, with conditions   
   escalating over time. "Three-   
   quarters of the mice that were ostensibly healthy developed one of the   
   behaviors after 12 weeks on the new diet," Garner said.   
      
   Some of the mice also developed ulcerated dermatitis, a fatal skin condition   
   that was thought to be caused by an unidentified pathogen or allergen. Garner   
   saw that the only mice that contracted the condition were the scratchers.   
      
   "What if ulcerated dermatitis, like skin-picking, another common behavioral   
   disorder, is not really a skin disease at all?" Garner mused. "We now have   
   evidence that it may be a behavioral disorder instead."   
      
   When taken off the new diet, the negative behaviors stopped developing in the   
   mice. When control mice were switched to the new diet, they started scratching   
   and barbering.   
      
   The study raises questions of how diet might be affecting other behavioral or   
   mental illnesses such as autism, Tourette syndrome, trichotillomania and   
   skin-picking. He said that before now, a link between diet and the onset of   
   mental disorders hadn't    
   been shown.   
      
   "What if the increase of simple sugars in the American diet is contributing to   
   the increase of these diseases?" Garner wonders. "Because we fed the mice more   
   tryptophan than in the typical human diet, this experiment doesn't show that,   
   but it certainly    
   makes it a possibility." Garner next wants to refine the experiments to better   
   imitate human dietary habits, including the amount of tryptophan people   
   consume.   
      
   Related:   
   Psychiatric disorders common among young adults   
   Hygiene Hypothesis linked to depression   
   Adolescent Mental Health Studies Cause Alarm   
   Dung Critter Lifts Mood   
   Eating disorders lurking in most wom   
      
      
      
   http://www.scienceagogo.com/news/20101113194823data_trunc_sys.shtml   
      
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