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.