Journal of Nature and Science (JNSCI), Vol.3, No.1, e300, 2017

Medical Sciences

 

Gluten-free/Casein-free Diet Improves Behavior in a Subset of Children with an Autism Spectrum Disorder

 

Jeffrey M. Kornitzer1, Deborah Horenstein1, Keith W. Pecor2, and Xue Ming1

 

1Division of Child Neurology, Department of Neurology, New Jersey Medical School, Rutgers 每 The State University of New Jersey, Newark, New Jersey, USA. 2Department of Biology, The College of New Jersey (TCNJ), Ewing, New Jersey, USA

 


This study investigated whether a gluten-free/casein-free (GFCF) diet was associated with amelioration of behavioral symptoms, language, and gastrointestinal symptoms in children with autism spectrum disorders (ASDs). A retrospective chart review compared gastrointestinal, developmental, and behavioral symptoms in children with ASDs and gastrointestinal complaints on a GFCF diet to those not on a GFCF diet.  Individuals on the GFCF diet were more likely to have reported improved speech (p < 0.001), behavior (p < 0.001), and severity of gastrointestinal symptoms (p = 0.038) than children in the control group.  Particularly noteworthy, all children with regressive ASDs on the GFCF diet reported improvement in behavior and/or language.  In this cohort, the GFCF diet was generally well-tolerated and without any serious adverse effects.   

 

Autism spectrum disorders (ASDs) | Gluten-free/casein-free (GFCF) diet | Dietary interventions | Regressive autism | Non-regressive autism

 

Background

Effective treatment modalities for the autism spectrum disorders (ASDs) remain stubbornly elusive.  Although a handful of medications may alleviate psychiatric symptoms associated with ASDs1-4, no treatments have emerged that can reliably manage other core features of autism, including communication disturbances, lack of sociability, sensory integration irregularities, and stereotyped behavior.  One burgeoning area of interest has been dietary interventions.  Already common place in the management of other neurologic disorders such as epilepsy, dietary interventions for the ASDs have been explored as an approach that could improve core features of the ASDs as well as the frequent comorbid gastrointestinal symptoms in some children with ASDs.  Children with ASDs may suffer from high rates of abdominal pain, chronic constipation, diarrhea, and gastrointestinal reflux5-13A growing body of research showing intrinsic abnormalities in intestinal anatomy14 and alterations in gut microbiota15-22 supports the link between ASDs and gastrointestinal disturbances.  A cause-and-effect relationship between an altered gut state and the core autistic neuropsychiatric symptoms has even been suggested23, 24.  Given that children with ASDs may have an increased rate of gastrointestinal ailments, much attention has been given to diet as a modifiable variable for children with ASDs.  In fact, therapies involving dietary modifications are the most common form of complementary and alternative medicine (CAM) used by families in the treatment of ASDs; of these diets, the most commonly employed is the gluten-free/casein-free (GFCF) diet25.

An association between ASDs and autoimmunity provides one theoretical underpinning for the use of the GFCF diet in children with ASDs.  There has been mounting evidence that a subset of children with ASDs have antibodies to gliadin and casein26-29.  One of the two primary components of gluten, the protein gliadin is found in most grains (wheat, barley, spelt, and rye).  Casein is a protein that is found in all mammalian milk.  A diet that is devoid of both gluten and casein-containing foods, known as the gluten-free/casein-free (GFCF) diet has become one of the most attempted interventions for children with ASDs30

Numerous interventional studies have examined the effect of the GFCF diet on children with ASDs.  Studies using parental reports have noted improvement in assessed behaviors after implementation of the GFCF diet31-33.  Among those studies, interval improvement in gastrointestinal symptoms was also reported32.  Interestingly, one of the studies noted that those with more severe pre-treatment gastrointestinal symptoms had more impressive post-treatment behavioral improvement33.  Two randomized, controlled studies found that children with ASDs on a GFCF diet showed significant improvements in both behavior and communication34,35. At the same time, several studies including one randomized, double blind study did not find any significant improvement in behavior in children with ASDs on a GFCF compared to a placebo group36, 37.  Due to a lack of large-scale, randomized studies, coupled with the possibility of adverse consequences associated with GFCF diets, several reviews did not find sufficient evidence to uniformly recommend the GFCF diet for all children with ASDs38-41

     Given the seemingly inconsistent results among these various studies, it is difficult to arrive at a cohesive understanding of the role that the GFCF diet may play in the management of ASDs.  It may be that some of the heterogeneity of results stems from the intrinsic heterogeneity of the population.  Increasingly, it is recognized that, as the name of the entity itself implies, the ASDs are a spectrum of disorders42-44.  Given the diversity of the ASDs at a clinical and even pathophysiological level, it may be difficult to find a treatment modality that reliably works within the entire population.  One mode to identifying an appropriate treatment modality then becomes to identify characteristics of specific subpopulations within the larger cohort of ASDs that respond to particular treatments.  Consistent with this approach, a consensus report by the American Academy of Pediatrics, while finding that a GFCF diet could not be routinely recommended in ASDs, did observe there could be subgroups that do respond to elimination diets45.  We hypothesized that, in line with previous findings from other groups, there would be an improvement in behavior, language, and gastrointestinal symptoms with use of the GFCF diet.  Furthermore, a subgroup within the larger population of children with ASDS would specifically be ※responders§ to the GFCF diet. 



Table 1. Six-point Gastrointestinal Severity Index  (6-GSI) scoring system.  Up to two points are assigned for each of the six symptoms.  A higher 6-GSI score reflects more severe symptoms.


 

Score

 

0

1

2

Constipation

> 5 stools per week

3-4 stools per week

0-2 stools per week

Diarrhea

0-1 loose stools per day

2-3 loose stools per day

> 4 loose stools per day

Average Stool Consistency

Formed

Loose/unformed > 3 days per week

Watery > 3 days per week

Stool Smell

Normal

Abnormal > 3 days per week

Unusually foul > 3 days per week

Flatulence

Normal

Frequent > 3 days per week

Daily

Abdominal pain

None

Mild discomfort > 3 times per week

Moderate to severe discomfort > 3 times per week

 

Table 2. Subject Age, Gender, Subtype of ASD, Gastrointestinal (GI) Severity Index scores

 

Control Group

(Not on GFCF Diet)

Intervention Group

(On GFCF Diet)

Number of Subjects

45

21

Average Age (years)*

12.6

12.2

Proportion of Males

82%

(N=37)

67%

(N=14)

Proportion of regressive-type ASDs

9%

(N=4)

38%

(N=8)

Average Initial GI Severity Index Score

3.0

3.4

Average GI Severity Index Score after GFCF Diet or equivalent time (10 months)

1.5

0.9

 * Age at time of final analysis of behavior and language. (GFCF= Gluten-free/ Casein-free; ASDs= Autism spectrum disorders)

 

 


Methods

 

Design

The study was conducted through a retrospective chart review of patients seen by both the Division of Child Neurology and the Division of Pediatric Gastroenterology in Rutgers-New Jersey Medical School in Newark, NJ, USA.  On the basis of an extensive history and physical/neurological examination, a Child Neurologist made the diagnosis of an ASD consistent with the clinical definition in the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision (DSM-IV-TR)46.  Further history was obtained in order to determine whether the patient had consistent developmental delays since birth (※non-regressive§) or whether the patient had apparently normal development followed by a regression of milestones such as loss of words previously used persistently, loss of eye contact, loss of gestures, and loss of ability to respond to names (※regressive§).  A pediatric gastroenterologist evaluated each subject and assessed the quality and severity of their gastrointestinal symptoms.  Upon chart review, this information was quantified using a modified version of the GI Severity Index [Table 1].  This 6-item scale assigns up to two points each for constipation, diarrhea, average stool consistency, stool smell, flatulence, and abdominal pain, with a higher score correlating with more severe symptoms18, 47.  Based upon parental preference, some of the patients were started on a GFCF diet.  Parental reports of behavioral symptoms as well as communication skills both before and after the diet were compared to reports obtained at similar time intervals from children with ASDs and abdominal symptoms not on the GFCF diet. 

 

Study Population

The subjects were children with ASDs ages 8 to 24 years old (mean age 12.5 years; standard deviation 4.7) [Table 2].  With 77.3% of the subjects being male, the gender distribution is consistent with the known male predilection for ASDs, as represented in the approximate 4.7:1 male-to-female ratio of ASDs in New Jersey48.  The subjects were from the greater Newark, New Jersey area and surrounding neighborhoods; the majority of subjects were insured by Medicaid.  Among the subjects of this study, twelve had a regressive-type ASD and the remainder (fifty-four children) had a non-regressive ASD.  Only children with an idiopathic ASD, that is an ASD without a clear underlying genetic or other predisposing syndrome, were included in this study.  In order to avoid the confounding variable of having overt celiac disease (which necessitates treatment with a gluten-free diet), any child with seropositivity to tissue transglutaminase and/or endomysial antibody was excluded from the study. 

This study was approved by the Rutgers-New Jersey Medical School Institutional Review Board.  The written consent process was waived because this was a retrospective study. 

 

Data Collection

A retrospective chart review was performed, collecting data on all common patients with a diagnosis of an ASD who were seen by both Child Neurology and Pediatric Gastroenterology prior to the onset of data collection and for at least the extent of the studied time interval.  After collecting demographic data, patients were stratified into two groups: intervention (that is, on a GFCF diet) and control (that is, not on a GFCF diet).  Results of behavioral and language assessments by Child Neurologists were used to establish pre-intervention and post-intervention measures for those on the GFCF diet.  Differences in those assessments were used to compare improvement in the control group over the same time frame of six to twelve months (mean of 9.5 months).  Improvements in behavior were defined as less frequent stereotyped behavior or less frequent aggressive behavior.  Improvement in language was defined as an increase in the number of expressed words.  Based upon information gleaned from the Pediatric Gastroenterologist, a score for the GI Severity Index was assigned for the end point, too. 

 


Figure 1. Change in Gastrointestinal (GI) Severity Index score by group.  The change in GI Severity Index score is calculated as pre-treatment score minus post-treatment score.  Therefore, a higher change in GI Severity Index score reflects a greater relative improvement in GI symptoms as measured by the scale.  (GFCF = Gluten-free/Casein-free).

 

 


Data Analysis

In evaluating gastrointestinal (GI) severity, the score after the conclusion of the experimental diet or control period was subtracted from the score before the inception of the diet / control to provide a measure of change. As such, a negative change in GI severity would indicate a worsening of symptoms, and a positive change would indicate a lessening of symptoms.  The data for GI severity changes were ranked and contrasted using a Mann-Whitney U test.  For speech and behavior, observed and expected values for improvement and absence of improvement were contrasted between diet treatments using contingency tables.  All statistical calculations were made using SPSS Statistics v21-23.

 

Results

 

Tolerability

There were a total of 66 patients for whom we had follow-up information.  Of those 66 patients, 21 patients tried the GFCF diet.  Patients were maintained on the diet, on average, for 9.5 months (Standard Deviation = 7.97 months).  The most common reasons for discontinuing the diet were that it was too difficult to adhere to or that no improvement on the diet was noted.  Parents of children on the GFCF diet did not note worsening gastrointestinal symptoms or weight loss.  In addition, there was no worsening of either language or behavior in any patient on the GFCF diet, as compared to the control group in which 18% of the patients received reports of worsening behavior and/or language over the same time frame.

 

Gastrointestinal Symptoms

GI Severity Index score reduction was significantly greater in the experimental diet treatment than in the control treatment (U = 325, p = 0.038) [Figure 1].  Of particular note, 33% of those individuals on the experimental diet saw a reduction in GI severity symptoms of four or more. 

 

Behavior and Language

Of the twenty-one patients on the GFCF diet, sixteen patients (76%) had improvement in language, behavior, or both.  Of the forty-five patients not on a dietary intervention, only one patient was reported to have had improvement in behavioral symptoms and this was related to toileting behavior.  Eight patients out of those forty-five patients (18%) actually had worsening of their autistic symptoms, specifically of behavior. 

Individuals on the experimental diet were more likely than individuals in the control treatment to receive reports of improved speech (聿 2 = 22.33, df = 1, p < 0.001) and improved behavior (聿2 = 30.52, df = 1, p < 0.001).  No individuals in the control treatment experienced improvement in speech, whereas 43% of individuals in the diet treatment experienced improvement in speech.  Similarly, only 2% of individuals in the control treatment experienced improvement in behavior, compared to 62% of individuals on the experimental diet.

Although the study numbers were too small for subgroup analysis, it is interesting to note that of the twenty-one patients on the GFCF diet, eight patients had a regressive-type ASD [Figure 2].  Interestingly, all eight of these patients had improvement in at least one domain: two patients showed improvement in language only, one patient showed improvement in behavior only, and five patients showed improvement in both language and behavior.  Of the forty-five patients not on a dietary intervention, four had a regressive-type ASD. None of these four patients had improvement and one actually had worsening behavior. 

 

Figure 2. Breakdown of subject population into subtype of autism spectrum disorder.  (GFCF = Gluten-free / Casein-free diet).

 

 

Discussion

In concert with our hypothesis, parents reported that children with ASDs on the GFCF were significantly more likely to have improvements in behavior, language, and gastrointestinal symptoms.  In addition, there seemed to be tolerability to the diet.  These findings are similar to previously published studies that have noted improvement in measured behaviors after implementation of the GFCF diet31-35. While improvement of behaviors was reported in the GFCF group, no improvements were consistently noted in the control group. If anything, worsening or fluctuating behaviors were reported in the control group. While a concern for constipation and worsening gastrointestinal symptoms has been offered as a reason not to start a GFCF diet 39, 40, the data in this study suggests that a GFCF diet may actually improve the severity of gastrointestinal symptoms.  Furthermore, no serious side effects were reported.    

The exact mechanism as to why a GFCF diet may improve the symptoms in children with an ASD remains to be understood.  One hypothesized mechanism of the GFCF diet*s utility is the elimination of deleterious antibodies through the removal of ingested antigens (gluten and casein).  In this cohort, though, none of the children were positive for the presence of the tissue transglutaminase antibody (which is used as a screening tool for celiac disease) or other celiac antibodies.  In fact, none of the children could be defined, at least in the conventional sense, as having celiac disease.  There is evidence that antibody seropositivity can both screen for and actually diagnose celiac disease in symptomatic children.  While quantification of serum antibodies has long been used as a screening tool for celiac disease and endoscopy with biopsy has been used as the diagnostic gold standard, elevated ※celiac§ antibody titers such as tissue transglutaminase antibody may actually be sufficient to diagnose celiac disease in children49,50. In fact, duodenal histology consistent with celiac disease has been demonstrated to be correlated with seropositivity for tissue transglutaminase and endomysial antibody levels in children51.  As such, by excluding children with seropositivity to tissue transglutaminase and endomysial antibody, all children with classic celiac disease were likely excluded from the study.   

At the same time, the frequency of patients with sensitivity to gluten in the absence of classic ※celiac§ antibodies or histological findings seems to far outnumber those with seropositivity for antibodies or histological findings consistent with celiac disease52.  To our knowledge, no studies have firmly established an explanation for this phenomenon.  It is not clear whether children with ASDs still have a form of celiac disease or gluten-sensitivity that is not diagnosable with current techniques.  The increased prevalence of antibodies to gliadin and casein in children with ASDs 26-29 provides one rational explanation as to why a diet devoid of gliadin and casein may lead to clinical improvement.  Even in children without obvious presence of these antibodies, there may be an overall increased presence of auto-antibodies53-57.  A gluten-free diet may reduce inflammation by eliminating antigens and may even be protective against auto-immunity58, 59.  Although the sample size was too small to warrant statistical analysis, children with regressive ASDs seemed to respond disproportionately better to the GFCF diet. It may be that regressive-type ASDs, which are marked by pro-inflammatory immune dysfunction especially in the gut60, 61, are sensitive to the anti-inflammatory effects of the GFCF diet.  In addition, we speculate that regressive-type ASDs have a distinctly abnormal gut microbiota62, 63 which may also be responsive to dietary interventions.          

Obvious limitations of this study include its retrospective nature, lack of randomization, lack of a mechanism to ensure adherence to the GFCF diet, and not using a formal assessment tool for behavioral and language symptoms, and other interventions such as speech or behavioral therapies were not standardized among the two groups.  The small number of children with regression-type ASDs also prohibited subgroup analysis for this variable.  Still, based upon the data in this study, it appears that in a subset of children with an ASD and gastrointestinal symptoms the GFCF is a relatively well-tolerated intervention that may improve gastrointestinal symptoms and perhaps behaviors.  This effect may be greater in children with a regressive ASD, but further research with a larger population would be needed to validate this hypothesis. 

 

Acknowledgements

We thank Dr. Iona Monteiro (Division of Gastroenterology, Department of Pediatrics, Rutgers-New Jersey Medical School, Newark, NJ) for assisting in obtaining patients for this study.  We thank Malky Korenblit for assistance in extracting data from patient charts.   

 

Author Contributions: JK participated in study design, data collection, analysis, data interpretation, and wrote the initial draft of the manuscript.  DH and XM participated in study design, data collection, analysis, data interpretation, and manuscript revision. KP participated in data analysis and preparation of tables and results section. All authors participated in preparing and approving the final version of the manuscript.

 

Authors* Note: The study was performed at Rutgers-New Jersey Medical School in Newark, New Jersey.

 

Declaration of Conflicting Interests: The authors have no conflicts of interest. 

 

Funding: This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors. The authors received no financial support for the research, authorship, and/or publication of this article.

 

Ethical Approval: This study was approved by the Rutgers-New Jersey Medical School Investigational Review Board. 


 

 


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Abbreviations: ASDs 每 autism spectrum disorders;

GFCF 每 gluten-free/casein-free

* Corresponding Author: Jeffrey M. Kornitzer, MD, Division of Child Neurology, Department of Neurology, New Jersey Medical School, Rutgers 每 The State University of New Jersey, Suite 5200, Doctor*s Office Center, 90 Bergen Street., Newark, NJ 07101-1709, USA.

Phone: (973) 972-7151. Email: j.kornitzer@rutgers.edu.

© 2017 by the Journal of Nature and Science (JNSCI).