Gastrointestinal abnormalities in children with autistic disorder
Journal of Pediatrics
Volume 135 • Number 5 • November 1999
Copyright © 1999 Mosby, Inc.
Karoly Horvath MD, PhD
John C. Papadimitriou MD, PhD
Anna Rabsztyn
Cinthia Drachenberg MD
J. Tyson Tildon PhD
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From the Departments of Pediatrics and Pathology, University of
Maryland School of Medicine, Baltimore.
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Supported by an intramural grant by the University of Maryland
School of Medicine.
Submitted for publication Dec 31, 1998.
Revision received May 20, 1999.
Accepted July 21, 1999.
------------------------------------------------------------------------
Reprint requests: Karoly Horvath, MD, PhD, Department of
Pediatrics, 22 S Greene St, N5W70, Box 140, Baltimore, MD
21201-1595.
Copyright © 1999 by Mosby, Inc.
0022-3476/99/$8.00 + 0 9/21/101636
Objectives: Our aim was to evaluate the structure and function of
the upper gastrointestinal tract in a group of patients with
autism who had gastrointestinal symptoms.
Study design: Thirty-six children (age: 5.7 ± 2 years, mean ± SD) with autistic
disorder underwent upper gastrointestinal endoscopy with biopsies, intestinal
and pancreatic enzyme
analyses, and bacterial and fungal cultures. The most frequent
gastrointestinal complaints were chronic diarrhea, gaseousness,
and abdominal discomfort and distension.
Results: Histologic examination in these 36 children revealed
grade I or II reflux esophagitis in 25 (69.4%), chronic gastritis
in 15, and chronic duodenitis in 24. The number of Paneth's cells
in the duodenal crypts was significantly elevated in autistic
children compared with non-autistic control subjects. Low
intestinal carbohydrate digestive enzyme activity was reported in
21 children (58.3%), although there was no abnormality found in
pancreatic function. Seventy-five percent of the autistic
children (27/36) had an increased pancreatico-biliary fluid
output after intravenous secretin administration. Nineteen of the
21 patients with diarrhea had significantly higher fluid output
than those without diarrhea.
Conclusions: Unrecognized gastrointestinal disorders, especially
reflux esophagitis and disaccharide malabsorption, may contribute
to the behavioral problems of the non-verbal autistic patients.
The observed increase in pancreatico-biliary secretion after
secretin infusion suggests an upregulation of secretin receptors
in the pancreas and liver. Further studies are required to
determine the possible association between the brain and
gastrointestinal dysfunctions in children with autistic disorder.
(J Pediatr 1999;135:559-63)
See editorial, p. 533.
Autistic disorder belongs to the group of pervasive developmental
disorders as defined by both the American (Diagnostic and
Statistical Manual of Mental Disorders, Fourth Edition)[1] and
international (International Classification of Diseases, Ninth
Revision) diagnostic systems. Autistic disorder implies severity
of disturbance in multiple areas of development reflected in a
marked lack of development of social interaction and
communication; restricted, repetitive, and stereotyped patterns;
and typical prelinguistic communicative behaviors. In addition to
the abnormalities in communication and language skills, these
children frequently have aggressive and self-injurious behaviors.
Sudden unexplained irritability or aggressive behavior, nighttime
awakening, and pushing on the abdomen are usually considered part
of the behavioral problems associated with autism.
Many parents report gastrointestinal symptoms in their autistic
child; however, until recently, gastrointestinal symptoms of
these children received little attention. In 1996, D'Eufemia et
al[2] reported increased intestinal permeability in 9 of 21 (43%)
patients with autistic disorder. The report of Wakefield et al[3]
represents the first effort to evaluate the gastrointestinal
tract in children with autism. In a recent case report we
described 3 children with autistic spectrum disorder and chronic
diarrhea who had an increased pancreatico-biliary secretory
response after secretin injection, suggesting that
gastrointestinal dysfunction might be associated with this
pervasive developmental disorder.[4]
This report describes several gastrointestinal abnormalities in
low-functioning autistic children and underlines the importance
of comprehensive gastrointestinal evaluations.
PATIENTS AND METHODS
Children diagnosed with autistic disorder or pervasive
developmental disorder, not otherwise specified by professionals
with expertise in behavioral pediatrics were referred to our
gastroenterology clinic for further evaluation.
Thirty-six children with one or more of the following symptoms
including abdominal pain (n = 25), chronic diarrhea (n = 21),
gaseousness/bloating (n = 21), nighttime awakening (n = 15), and
unexplained irritability (n = 18) underwent
esophagogastroduodenoscopy. The mean age of these patients was
5.7 years (5.7 ± 2 years, mean ± SD; range, 2.5-10 years; 33
boys).
Their medical history revealed that 64% of these children were
breast-fed for an average of 6.7 months, 36% had a history of
cow's milk and/or soy protein intolerance, and 44.4% had allergy
to foods according to the parents and care givers interviewed at
the outpatient clinic. Seventeen (47.2%) children were on a
casein-free and/or gluten-free diet at the time of evaluation.
Clinical Investigations
Patients fasted after midnight, and the procedures were performed
the next morning with patients under general anesthesia. The full
upper gastrointestinal workup included esophageal, gastric, and
duodenal biopsies for histology, measurement of the digestive
enzymes of the small intestine (lactase, maltase, sucrase,
palatinase, glucoamylase) and pancreas (lipase, amylase, trypsin,
chymotrypsin, and carboxypeptidases A and B), and bacterial and
fungal cultures. The normal values for intestinal enzymes were
based on the measurements on 104 histologically normal intestinal
biopsy tissues. The normal values for pancreatic enzymes were
established by measurement on 215 specimens collected from
children. Antibiotic and antifungal therapies were discontinued a
week before the endoscopy to allow culture of the duodenal fluid.
All fluids for cultures were obtained before pancreatic
stimulation to avoid the dilution of juice resulting in falsely
low quantitative counts. The pancreatic enzyme activities were
measured from specimens collected before and after secretin
stimulation.
For the collection of pancreatic juice, we stimulated the fluid
secretion with secretin (Ferring Laboratories, Inc, Suffern, NY),
2 cat units (CU)/kg body weight, given intravenously within 1
minute. The pancreatico-biliary juice was collected after
positioning the endoscope distal to the ampulla of Vater, and the
fluid was collected by moving the tip into the outcoming fluid
and suctioning it into a collector trap. In a few cases an
endoscopic retrograde cholangiopancreatography catheter was
placed into the channel of the endoscope, and fluid was suctioned
into a syringe.
A basal sample was collected in the duodenum around the Vater
papilla before the secretin injection and was sent for enzyme
analysis and bacterial and fungal cultures. Three additional
specimens were collected after the secretin injection within a 5-
to 10-minute period. The pancreatic enzyme activities were
measured in all collected aliquots. The volume of secreted fluid
after secretin administration was measured and recorded in
milliliters per minute. The normal fluid output was based on the
data from 26 non-autistic patients who underwent the same
procedure. The duodenal biopsy specimens were obtained after the
fluid collections to avoid blood contamination. Endoscopic
grading of esophagitis was based on the description of Leape at
al[5] for pediatric patients.
Histology
The histologic grading of esophagitis followed the scores
described by the Working Group on Gastro-Oesophageal Reflux
Disease of the European Society of Paediatric Gastroenterology
and Nutrition.[6] The histologic criteria for reflux esophagitis
included eosinophilic and/or polymorphonuclear infiltrate, basal
layer thickening, and papillary hypertrophy.
Gastric biopsy specimens were stained with Giemsa stain to
determine the presence of Helicobacter pylori infection.
The histology slides were examined by surgical pathologists and
were further reviewed by 3 authors (J.P., C.D., and K.H.) in an
observer-blinded fashion. In the intestinal specimens, the number
of intraepithelial lymphocytes, lamina propria cell density,
villus/crypt ratio, and mitoses in crypts were assessed. The
number of Paneth's cells per crypt was counted in all 36 patients
with autism and compared with 22 biopsy specimens from
non-autistic pediatric patients (12 immunocompetent and 10
immunodeficient) who underwent endoscopy because of failure to
thrive, chronic diarrhea, or suspected celiac disease.
Ethical Approval and Consent
The project for the examination of the effect of secretin
injection was approved by the Internal Review Board of University
of Maryland School of Medicine. Informed written consent was
obtained from each parent before endoscopy and secretin infusion.
Statistical Analysis
Data were expressed as mean ± SD. In all comparisons between
groups the Student t test was used, and a P value of <.05 was
considered significant.
RESULTS
Histologic Findings
The most frequent histologic finding was the presence of reflux
esophagitis in 25 of 36 children (69.4%). Twenty-two of these 25
children (88%) had symptoms such as nighttime awakening with
irritability, signs of abdominal discomfort, or pushing on the
abdomen, which are typically reported by non-autistic children
with esophagitis. Chronic inflammation of the gastric mucosa was
present in 15 children. None of the patients had H pylori
infection. Chronic nonspecific duodenal inflammation was found in
24 children (66.6%). Two children had grade II partial villus
atrophy, but they did not have serologic or histologic evidence
of celiac disease (on gamma/delta lymphocyte staining).
Paneth's cell hyperplasia was evident in the duodenal biopsy
specimens. We performed a morphometric analysis and compared the
number of Paneth's cells seen in the crypts with those of 22
non-autistic control subjects and found an elevated number of
Paneth's cells per crypt (3.09 ± 0.46 vs 2.07 ± 0.32; P <
.05). Furthermore, the Paneth's cells were frequently enlarged,
and discharge of granules into the crypt lumen was a typical
finding. There was no difference in the number of cells between
patients with and those without diarrhea (3.04 ± 0.53 vs 3.16 ± 0.34 cells/crypt).
Fig 1 shows the number of Paneth's cells counted in the studied patients and
the 2 groups of control
subjects.
Fig. 1. Paneth's cell counts in children with autistic disorder,
normal control subjects, and immunodeficient patients (HIV). PDD,
Pervasive developmental disorder; HIV, human immunodeficiency
virus.
Enzyme Assays
Decreased activity (<1 SD below normal values) of one or more
disaccharidases or glucoamylase was found in 21 children (58.3%);
10 children had decreased activity in 2 or more enzymes. The most
frequent finding was a low lactase level, which was present in 14
patients (<9.4 IU/g/min). All of the 21 children with low
enzyme activities had loose stools and/or gaseousness. None of
these 36 children had pathologic pancreatic enzyme activities
after secretin stimulation.
Pancreatico-Biliary Fluid Output for Secretin
Fig 2 shows the secretory responses in the 2 groups of children
with autistic disorder and control subjects.
Fig. 2. Pancreatico-biliary fluid output after administration of
secretin, 2 CU/kg body weight, in children with autistic disorder
with and without diarrhea and in control subjects.
The average pancreatico-biliary fluid output was significantly
higher (3.8 ± 2.2 mL/min) for the autistic group compared with
the control group (1.46 ± 0.57 mL/min; P < .05). In 27
children (75%) the volume of pancreatico-biliary fluid output
after secretin stimulation was 1 SD above the values of
non-autistic patients. Nineteen of the 21 patients (90.47%) with
the main symptom of chronic diarrhea had significantly higher
fluid output compared with that of control subjects. There was a
statistically significant difference between patients with
diarrhea (n = 21) and those without diarrhea (n = 15) (4.8 ± 2.3
mL/min vs 2.4 ± 1.3 mL/min; P < .05). An important clinical
observation was that autistic children with chronic diarrhea
showing the high fluid response with secretin had an improved
stool consistency after the procedure, and it lasted for a few
weeks or was sustained.
Duodenal Fluid Culture
There was no evidence of either fungal or bacterial overgrowth in
the duodenum, even in those 12 patients who, on the basis of
urine organic acid test results, were suspected of having such
overgrowth.
DISCUSSION
Few studies have addressed gastrointestinal problems in children
with autistic disorder. Goodwin et al[7] studied 15 randomly
selected children with autism and found that 6 had either bulky,
odorous, or loose stools or intermittent diarrhea; one had celiac
disease. In a recentstudy, 43% of the autistic patients without
symptoms or evidence of any gastrointestinal disease had altered
intestinal permeability.[2] Low concentrations of serum alpha1
-antitrypsin were reported in children with typical autism,[8] a
finding that is indicative of intestinal protein loss. In a
recent case report we presented gastrointestinal and behavioral
observations on 3 children with autistic spectrum disorder.[4]
Although gastrointestinal symptoms frequently accompany the
manifestations of autism, little attention has been paid to this
aspect of this developmental behavioral disorder, and a
gastrointestinal workup has not been part of the regular medical
evaluations. Sudden unexplained irritability or aggressive
behavior, mood change, discomfort, and nighttime awakenings in
these children were considered to be part of the brain
dysfunction and not manifestations of organic problems. A
significant percentage of children with autistic disorder are
reported to be low functioning and have only prelinquistic
communicative behavior. A plausible reason for the paucity of
gastrointestinal evaluation of these children may be their
inability to verbalize and describe their abdominal pain or
discomfort and a lack of cooperation in non-invasive studies,
such as breath tests.
The upper gastrointestinal evaluations of children with autistic
disorder support the presence of a chronic inflammatory process
in the gut, as reported by Wakefield et al.[3] They
performedcolonoscopy with histologic examinations in 12 children
and reported that all had intestinal abnormalities, ranging from
lymphoid nodular hyperplasia to aphthoid ulceration. [3] In our
study chronic inflammation of the esophagus, stomach, and
duodenum was the major and most consistent finding.
The most frequently detected abnormalities in children with
autistic disorder included a high prevalence of reflux
esophagitis, hyperplasia of duodenal Paneth's cells, intestinal
carbohydrate digestive enzyme deficiencies, and an unusual
hypersecretory response to intravenous secretin administration.
A significant portion (25/36) of autistic children had
gastroesophageal reflux and reflux esophagitis. There are no
age-related data on the prevalence of gastroesophageal reflux
disease in the 2.5- to 10-year-old group. The prevalence of
reflux esophagitis is low (estimated 2%) in Western countries.[9]
It is known that both neural and humoral factors can have an
effect on the lower esophageal sphincter. People under stress are
more likely to have dysmotility and reflux. It is known that
secretin has a suppressive effect on gastric secretion. [10]
Whether a low secretin level may contribute to the high
prevalence of acidic reflux in these children warrants further
investigation.
An elevation in the number of Paneth's cells was found in most of
the studied patients. Reportedly, the average count of Paneth's
cells in the crypts is about 5%, and there is no significant
difference in the number of these cells between the healthy and
inflamed duodenum[11] or in celiac disease.[12] Scott and
Brandtzaeg[12] reported that the average number of Paneth's cells
in healthy control subjects was 2 per crypt, which is similar to
that of our control subjects. We observed an ~50% increase in the
number of these cells in patients with autistic disorder. In
normal crypt base cross-sections, the size of Paneth's cells is
similar to that of the surrounding cells, and they are smaller
than the goblet cells. Many patients with autistic disorder had
enlarged Paneth's cells filled with huge granules. Hypertrophy
and hyperplasia of the Paneth's cells have been reported in
hamsters after ligation of pancreatic ducts,[13] and a varying
degree of increase in the number of Paneth's cells was described
in patients with chronic pancreatitis.[14] It is thought that
absence of pancreatic fluid favors the multiplication of Paneth's
cells. We did not find evidence of pancreatic insufficiency in
our patients. However, the high secretory response to secretin
might suggest the absence of regular secretin stimulation of the
pancreas and biliary tract. There are no data available regarding
the effect of secretin or cholecystokinin on Paneth's cells or
local immune defense of the intestine. Studies indicate that
Paneth's cells produce and release substances such as lysozyme,
defensins,[15] and alpha1 -antitrypsin.[16] The human intestinal
defensin 5 (HD-5) has antimicrobial activities against bacteria
and Candida albicans.[17] Paneth's cell metaplasia is a typical
finding in inflammatory bowel diseases involving the colon.[18]
Transmission electron microscopic studies in tissues from
patients with Crohn's disease showed that Paneth's cells were
increased in number and showed both focal granule extrusion and
cytoplasmic lysosomal inclusions.[19] Our studies revealed
similar findings, including a greater number of Paneth's cells
and increased granule discharge into the lumen of crypts.
However, although the presence of Paneth's cells represents a
metaplastic change in Crohn's disease, these cells are normally
present in the duodenum. The importance of this Paneth's cell
activation in patients with autistic disorder is not known and
warrants further investigation.
Children with autistic disorder frequently have loose, extremely
foul-smelling stools and gaseousness. These symptoms are not
associated with growth failure and cannot be explained by the
limited diet preference of these children. In most of the cases,
results of the routine stool tests are negative. Typically,
parents claim that the gastrointestinal and behavioral symptoms
are manifested in parallel. Our study showed that 58% of the
examined children had disaccharidase/glucoamylase enzyme
activities below the normal range. Carbohydrate malabsorption may
result in gaseousness with crampy abdominal pain and may be the
cause of chronic loose stools. The most frequent finding was a
low lactase activity in 14 of the 21 children with pathologic
disaccharidase results.
Children with autistic disorder and chronic diarrhea had a higher
pancreatico-biliary fluid output after secretin stimulation. This
high secretory response to secretin administration may indicate
an upregulation of the secretin receptors in the ductal cells of
the pancreas or in the bile-duct epithelium. In turn, this may
occur in the absence of normal secretin stimulation, which can be
the consequence of either a defect in secretin production or a
problem of release from the intestinal S cells.
In summary, our findings suggest that gastrointestinal
abnormalities may contribute to some of the behavioral problems
frequently described in these children. The presence of
esophagitis correlated well with the reported symptoms and may in
part explain the sudden irritability, aggressive behavior, or
nighttime awakenings in many of these children. The diarrhea and
gaseousness may be the consequence of decreased disaccharidase
activity and may also contribute to the behavioral problems.
Our results suggest a possible upregulation of secretin receptors
in the pancreas and the biliary tract and a high prevalence of
reflux esophagitis and chronic duodenitis associated with
Paneth's cell hyperplasia in a group of children with autistic
disorder who have various gastrointestinal symptoms. Further
gastrointestinal studies of children with autistic disorder may
contribute to a better understanding of the etiology of this
disorder.
We thank Lisa Medeiros, BSN, and Tina Sewell, BSN, for their help
with patient recruitment and during the procedures; their
contribution was important to accomplish this work. We are very
grateful to Lois Roeder, PhD, for her contribution in the
preparation of the manuscript.
REFERENCES
1. American Psychiatric Association. Diagnostic and statistical
manual of mental disorders. 4th ed. Washington (DC): American
Psychiatric Association; 1994.
2. D'Eufemia P, Celli M, Finocchiaro R, Pacifico L, Viozzi L,
Zaccagnini M, et al. Abnormal intestinal permeability in children
with autism. Acta Paediatr 1996;85:1076-9. abstract
3. Wakefield AJ, Murch SH, Anthony A, Linnell J, Casson DM, Malik
M, et al. Ileal-lymphoid-nodular hyperplasia, non-specific
colitis, and pervasive developmental disorder in children. Lancet
1998;351:637-41. abstract
4. Horvath K, Stefanatos G, Sokolski K, Wachtel R, Nabors L,
Tildon JT. Improved social and language skills after secretin
administration in patients with autistic spectrum disorders. J
Assoc Acad Minority Physicians 1998;9:9-15.
5. Leape LL, Bhan I, Ramenofsky ML. Esophageal biopsy in the
diagnosis of reflux esophagitis. J Pediatr Surg 1981;16:379-84. abstract
6. Vandenplas Y. Reflux esophagitis in infants and children: a
report from the Working Group on Gastro-Oesophageal Reflux
Disease of the European Society of Paediatric Gastroenterology
and Nutrition. J Pediatr Gastroenterol Nutr 1994;18:413-22. abstract
7. Goodwin MS, Cowen MA, Goodwin TC. Malabsorption and cerebral
dysfunction: a multivariate and comparative study of autistic
children. J Autism Child Schizophr 1971;1:48-62. citation
8. Walker-Smith J, Andrews J. Alpha-1-antitrypsin, autism, and
coeliac disease. Lancet 1972;2:883-4. citation
9. Wienbeck M, Barnert J. Epidemiology of reflux disease and
reflux esophagitis. Scand J Gastroenterol Suppl 1989;156:7-13. abstract
10. Chung I, Li P, Lee K, Chang T, Chey WY. Dual inhibitory
mechanism of secretin action on acid secretion in totally
isolated, vascularly perfused rat stomach. Gastroenterology
1994;107: 1751-8. abstract
11. Schmitz-Moormann P, Schmidt-Slordahl R, Peter JH, Massarrat
S. Morphometric studies of normal and inflamed duodenal mucosa.
Pathol Res Pract 1980;167:313-21. abstract
12. Scott H, Brandtzaeg P. Enumeration of Paneth cells in coeliac
disease: comparison of conventional light microscopy and
immunofluorescence staining for lysozyme. Gut 1981;22: 812-6. abstract
13. Balas D, Senegas-Balas F, Bertrand C, Frexinos J, Ribet A.
Effects of pancreatic duct ligation on the hamster intestinal
mucosa. Histological findings. Digestion 1980;20:157-67. abstract
14. Senegas-Balas F, Bastie MJ, Balas D, Escourrou J, Bommelaer
G, Bertrand C, et al. Histological variations of the duodenal
mucosa in chronic human pancreatitis. Dig Dis Sci 1982;27:917-22. abstract
15. Ouellette AJ. Paneth cells and innate immunity in the crypt
microenvironment. Gastroenterology 1997;113: 1779-84. abstract
16. Molmenti EP, Perlmutter DH, Rubin DC. Cell-specific
expression of alpha 1-antitrypsin in human intestinal epithelium.
J Clin Invest 1993;92:2022-34. abstract
17. Porter EM, van Dam E, Valore EV, Ganz T. Broad-spectrum
antimicrobial activity of human intestinal defensin 5. Infect
Immun 1997;65:2396-401. abstract
18. Stamp GW, Poulsom R, Chung LP, Keshav S, Jeffery RE,
Longcroft JA, et al. Lysozyme gene expression in inflammatory
bowel disease. Gastroenterology 1992;103:532-8. abstract
19. Dvorak AM, Dickersin GR. Crohn's disease: transmission
electron microscopic studies. I. Barrier function. Possible
changes related to alterations of cell coat, mucous coat,
epithelial cells, and Paneth cells. Hum Pathol 1980; 11(suppl
5):561-71. abstract