(RxWiki News) Everybody knows you are what you eat, but that adage doesn't apply solely to physical health.
In fact, diet, according to the research from Purdue University, might even be able to trigger the onset of mental illness.
In the study, mice were fed a diet high in sugar and tryptophan (an essential amino acid the body cannot manufacture and has to derive from food) that was expected to reduce abnormal hair-pulling. However the already-ill rodents increased their hair-pulling or started a new self-injurious behavior. Seemingly healthy mice developed the same abnormal behaviors after eating the sugary-rich diet.
Joseph Garner, an associate professor of animal sciences at Purdue, said the diet brought out the predispositions of the mice becoming either hair-pullers or scratchers.
"They're like genetically at-risk people," he said.
Trichotillomania is an impulse-control disorder in which people pull out their hair. The disorder occurrs disproportionately in women, who are are about four times more likely to develop the condition than men. It is believed to affect between 2 percent and 4 percent of the population.
Mice that pull their fur out have been shown to have low levels of serotonin (the neurotransmitter that affects mood and impulses) activity in the brain. Increasing serotonin activity in the brain might cure or reduce the mice's fur-pulling and possibly trichotillomania, Garner hypothesized.
Tryptophan manufactures seratonin in the brain, but the amino acid doesn't easily make it across the between the blood-brain barrier. Instead other amino acids get through and basically block the door for tryptophan. The sugars the mice ate triggered a release of insulin, which causes muscles to absorb the other amino acids, giving tryptophan a gateway to the brain. As a result of using eight times as much sugar and four times as much tryptophan, Garner was able to increase seratonin activity in the mice's brains, but their abnormal behaviors got worse and a great deal of those mice who did not exhibit abnormal behaviors started to do so.
"Three-quarters of the mice that were ostensibly healthy developed one of the behaviors after 12 weeks on the new diet," Garner said.
When taken off the new diet, the negative behaviors ceased development in the mice, and when control mice were switched to the new diet, they began to scratch and pull their fur.
Until this study, a link between diet and mental illness had not been established, according to Garner, who is looking into how diet may affect other behavioral or mental illnesses such as autism, Tourette syndrome, trichotillomania and skin-picking.
Garner suggested the results of the mice study might point to a link between an increase in simple sugars in American diets and an increase of these mental disorders.
Now that's food for thought.