Jenni Laidman
June 27, 2014
A gluten-free diet was associated with improved cognitive performance that correlated with mucosal healing in a small pilot study of patients with celiac disease published online May 28 and in the July issue of Alimentary Pharmacology and Therapeutics.
Irene T. Lichtwark, PhD student, School of Psychological Sciences, Monash University, Melbourne, Australia, and colleagues examined the connection among a gluten-free diet, celiac symptoms, and cognitive function among 11 newly diagnosed patients with celiac disease (8 women and 3 men) aged 22 to 39 years. The researchers tested patients for information-processing efficacy, memory, visuospatial ability, motor function, and attention before starting them on a gluten-free diet. The researchers tested patients again 12 weeks into the diet, and again after 1 year of adherence to the diet. The researchers conducted blood testing, intestinal permeability tests, and small bowel biopsies via gastroscopy at baseline, week 12, and week 52.
All patients adhered to the gluten-free diet. Tissue transglutaminase antibody levels improved from a mean baseline of 58.4 to 16.8 U/mL at 52 weeks (P = .025), and Marsh scores improved significantly (P = 0.001, Friedman’s test). The patients demonstrated significant improvement in 4 of the cognitive tests, and improvements in scores for verbal fluency, attention, and motor function at 52 weeks correlated strongly with Marsh scores and tissue transglutaminase antibody level improvements (r = 0.377 – 0.735; all P < .05). The research uncovered no meaningful correlations for nutritional or biochemical markers or markers of intestinal permeability.
“This study, while small in numbers, does provide objective evidence for the cognitive impairments associated with untreated coeliac disease,” corresponding author Gregory W. Yelland, PhD, told Medscape Medical News. Dr. Yelland is from the Department of Gastroenterology, Central Clinical School, Monash University, The Alfred Hospital, Melbourne. “We would like to think that clinicians would use this to inform their patients of the cognitive risks of remaining untreated and of the benefits of adhering to a strict gluten-free diet for not only their physical [health,] but their mental health also.”
The study provides an “objective evaluation” of the cognitive impairment that frequently accompanies celiac disease, and confirms such symptoms with a gluten-free diet, Alessio Fasano, MD, author of the book Gluten Freedom, told Medscape Medical News. Dr. Fasano, who was not involved with the study, is a spokesperson for the American Gastroenterological Association and chief of pediatric gastroenterology and nutrition at Massachusetts General Hospital for Children in Boston. “We have this kind of evidence in clinic all the time, even with people who have other forms of gluten reaction. This connection between the gut and the brain, and how gluten can have something to do with it, going from headaches to foggy mind, is something we see over and over again. [Patients] claim they can’t think straight any more or they can’t remember. There is a veil on their brain that lifts when they go gluten-free,” Dr. Fasano says.
The study confirms that celiac disease is often accompanied by a kind of “brain fog,” the study authors write. The authors say the level of cognitive impairment in their study group was roughly equivalent to the impairment of someone suffering severe jet lag or having a blood-alcohol level of 0.05 g/100 mL, which is the upper legal limit for drunken driving in Australia and many other countries. (The limit is 0.08 g/100 mL in the United States and Canada.)
“If these findings are confirmed in a larger study, they may have important health and safety implications,” the authors write. “When viewed together, the present results indicate that short-term memory, movement and processing speed are impaired in untreated [celiac disease,] and that they improve during adherence to a [gluten-free diet].”
Although the study shows cognitive improvements with a gluten-free diet, Dr. Fasano notes that improvement among the study participants was not uniform. Although most patients generally improved in the first 12 weeks of the diet, the patients lost ground by 52 weeks. Performance usually remained better than at baseline, however. “There’s a lot of variation,” Dr. Fasano says. “Some got better. Some saw no change. Some got worse. All this is to say in celiac disease, each individual can take a different course. That’s the beauty of statistics: It’s teaching you the lesson that you can’t make too much out of it when numbers are so limited.”
He concluded, “I believe this is a very provocative study, but we should think about this and really try to expand it with larger numbers.”
In addition to verifying the results in a larger trial, further research is required in other areas, Dr. Yelland said. “The 2 most important issues that now need to be addressed are (a) the mechanism by which celiac disease affects cognitive processing (b) and the extent to which changes in cognitive function reflect changes in intestinal health,” Dr. Yelland told Medscape Medical News. “The latter is particularly important, for if cognitive performance can be used as a gauge of intestinal health, it may reduce the need for patients to undergo colonoscopies.”
The study was funded by the Coeliac Research Fund (Coeliac Australia). Two coauthors have published books on celiac disease and its dietary management, and another coauthor and Dr. Yellend are patent holders for the Subtle Cognitive Impairment Test. Dr. Fasano is also the author of a book on celiac disease and owns stock in Alba Therapeutics, which is working on a complementary therapeutic to the gluten-free diet.
Aliment Pharmacol Ther. 2014;40:160-170. Full text
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