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Aug/Sep 2011 Issue
Research Roundup: Gluten Ataxia, Why We Cheat, ADHD & More!
The latest medical news for people with allergies and food sensitivities
Life on the Farm
Studies have shown that children living on farms are less likely to develop asthma. Why does farm life reduce the risk? Its thought that exposure to a greater diversity of microorganisms (bacteria and fungi) may play a protective role. To examine this theory, researchers from the University Children’s Hospital Munich looked at data on asthma rates among children with and without farm exposure and analyzed the DNA of microorganisms in dust samples taken from the children’s bedrooms and mattresses. In total, 933 dust samples were studied.
Results confirmed a lower prevalence of asthma among children living on farms and that the risk of asthma fell as the diversity of microorganisms increased.
Exactly how a greater diversity of microorganisms may protect against asthma isn’t clear but one theory is that continuous exposure to many different microorganisms makes it harder for species that may potentially induce asthma to become dominant in the lower respiratory tract.
Researchers also discovered certain classes of bacteria and fungi “of special interest.” When studied separately, the presence of these microorganisms was even more significantly associated with a reduced risk of asthma.
In a press release, the research team said its next challenge is to dig deeper into the nature of the link between certain microorganisms in household dust and their protective effect, with the long-term goal of identifying candidates that might serve as the basis for a vaccine against asthma. The study was published in The New England Journal of Medicine.
Testing for Gluten Ataxia
A test for antibodies against tissue transglutaminase 6 (TG6) is not able to distinguish celiacs with neurologic symptoms from those without such symptoms, according to new research published in Clinica Chimica Acta. Neurologic complications of celiac disease, like ataxia (clumsiness and problems with balance), cognitive deficits, tingling and numbness in extremities, etc., are widely reported but tests to help identify those at risk have yet to be developed. (Gluten sensitivity may also cause neurologic symptoms.)
In the study, researchers from the University of Tampere in Finland found that while following a gluten-containing diet, the number of TG6-positive celiacs with neurologic symptoms didn’t significantly differ from the number of TG6-positive celiacs without symptoms or from the healthy subjects who served as the control group. Moreover, TG6 antibodies didn’t decrease on a gluten-free diet.
TG6 is a member of the same transglutaminase family as TG2, detected in the screening test for celiac disease (tTG), but TG6 is primarily expressed in the brain, leading researchers to suspect it could serve as a marker of neurologic symptoms.
TG6 is still very promising, says neurologist Marios Hadjivassiliou, MD, one of the world’s leading researchers into the neurologic ramifications of celiac disease and gluten sensitivity. Hadjivassiliou points to the possibility of methodological flaws in the new research, indicating that the study’s findings aren’t consistent with what he’s seen. In fact, Hadjivassiliou reports there are a “number of papers in preparation” supporting TG6 as a useful marker of neurologic manifestations.
More research is needed into the neurologic aspects of celiac disease and gluten sensitivity, including how to accurately test for gluten ataxia.
Why We Cheat
Why can some people, including certain children, stick to a special diet while others struggle with it? Researchers find that celiacs with good dietary compliance have better internal “locus of control.”
Locus of control is an important psychological term that refers to the extent individuals believe they can control events that affect them. Those with better internal locus of control believe they play a part in establishing outcomes in life, that they’re not helpless victims of random circumstances. For example, a teen with a strong internal locus of control knows that if she studies hard, she’s apt to do well on a test, rather than feeling she has no control over her test score.
At the University of Trieste and Institute of Child Health in Trieste, Italy, 156 participants (mean age 10) on a gluten-free diet completed tests assessing their locus of control, compliance with the diet and the impact of celiac disease on their quality of life. Participants with stronger internal locus of control showed more dietary compliance and also reported a better quality of life than those with less internal control.
Researchers say the “locus of control” concept can be useful in identifying patients at risk for dietary lapses. In addition, they state that educational and psychological support to strengthen patients’ internal locus of control may be beneficial. The work was published in The Journal of Pediatrics.
ADHD and Other Behaviors
Children with ADHD often have secondary conditions, such as conduct disorder, anxiety, depression, learning disabilities or speech problems. Now in a study published in Pediatrics, researchers from UCLA’s Center for Healthier Children, Families and Communities found that 67 percent of children with ADHD had at least one other condition, while close to 20 percent had three or more. Findings were based on a telephone survey of the parents and guardians of more than 5,000 school-aged children with ADHD.
Researchers say the study supports an emerging view that “pure” ADHD–without any comorbidities—occurs in only a minority of cases. Parents and healthcare professionals should be aware of the high prevalence of additional problems that may occur alongside ADHD and screening is necessary, they conclude. Current American Academy of Pediatrics guidelines call for the assessment and management of comorbidity with ADHD.
More than Milk Allergy
In a study on milk allergy which included over 13,000 infants, approximately 0.3 percent were found to have a poorly defined and commonly misdiagnosed condition called Food Protein-Induced Enterocolitis Syndrome (FPIES). Pronounced "F-Pies," patients experience profuse vomiting, diarrhea and lethargy following the ingestion of certain foods. The most common triggers are cow’s milk (dairy) and soy but any food has the potential to set off an FPIES reaction. The condition affects infants and young children, with symptoms typically starting after the introduction of solid foods or formula, which may include dairy or soy.
The prevalence of FPIES triggered by milk, previously unknown, is actually significant, say the researchers and they underscore the importance of using an oral food challenge to diagnose the condition. They found most children (90 percent) outgrew FPIES to milk by age 3 but about 20 percent went on to develop a true IgE-mediated allergy to cow’s milk.
When reintroducing milk to FPIES patients, it should be done under close medical supervision, say researchers.
The study was published in the Journal of Allergy and Clinical Immunology.
Medical writer Christine Boyd lives in Baltimore.