Gastrointestinal abnormalities in children with autistic disorder

Spontaneous mucosal lymphocyte cytokine profiles in children with autism and gastrointestinal symptoms: mucosal immune activation and reduced counter regulatory interleukin-10

A lymphocytic enterocolitis has been reported in a cohort of children with autistic spectrum disorder (ASD) and gastrointestinal (GI) symptoms. This study tested the hypothesis that dysregulated intestinal mucosal immunity with enhanced pro-inflammatory cytokine production is present in these ASD children. Comparison was made with developmentally normal children with, and without, mucosal inflammation. Duodenal and colonic biopsies were obtained from 21 ASD children, and 65 developmentally normal paediatric controls, of which 38 had signs of histological inflammation. Detection of CD3+ lymphocyte staining for spontaneous intracellular TNFalpha, IL-2, IL-4, IFNgamma, and IL-10, was performed by multicolor flow cytometry. Duodenal and colonic mucosal CD3+ lymphocyte counts were elevated in ASD children compared with noninflamed controls (p<0.03). In the duodenum, the proportion of lamina propria (LP) and epithelial CD3(+)TNFalpha+ cells in ASD children was significantly greater compared with noninflamed controls (p<0.002) but not coeliac disease controls. In addition, LP and epithelial CD3(+)IL-2+ and CD3(+)IFNgamma+, and epithelial CD3(+)IL-4+ cells were more numerous in ASD children than in noninflamed controls (p<0.04). In contrast, CD3(+)IL-10+ cells were fewer in ASD children than in noninflamed controls (p<0.05). In the colon, LP CD3(+)TNFalpha+ and CD3(+)IFNgamma+ were more frequent in ASD children than in noninflamed controls (p<0.01). In contrast with Crohn's disease and non-Crohn's colitis, LP and epithelial CD3(+)IL-10+ cells were fewer in ASD children than in nondisease controls (p<0.01). There was a significantly greater proportion of CD3(+)TNFalpha+ cells in colonic mucosa in those ASD children who had no dietary exclusion compared with those on a gluten and/or casein free diet (p<0.05). There is a consistent profile of CD3+ lymphocyte cytokines in the small and large intestinal mucosa of these ASD children, involving increased pro-inflammatory and decreased regulatory activities. The data provide further evidence of a diffuse mucosal immunopathology in some ASD children and the potential for benefit of dietary and immunomodulatory therapies.

Evaluation of an association between gastrointestinal symptoms and cytokine production against common dietary proteins in children with autism spectrum disorders

OBJECTIVE

To evaluate an association between cytokine production with common dietary proteins as a marker of non-allergic food hypersensitivity (NFH) and gastrointestinal (GI) symptoms in young children with autism spectrum disorders (ASD).

STUDY DESIGN

Peripheral blood mononuclear cells (PBMCs) were obtained from 109 ASD children with or without GI symptoms (GI [+] ASD, N = 75 and GI (-) ASD, N = 34], from children with NFH (N = 15), and control subjects (N = 19). Diarrhea and constipation were the major GI symptoms. We measured production of type 1 T-helper cells (Th1), type 2 T-helper cells (Th2), and regulatory cytokines by PBMCs stimulated with whole cow's milk protein (CMP), its major components (casein, beta-lactoglobulin, and alpha-lactoalbumin), gliadin, and soy.

RESULTS

PBMCs obtained from GI (+) ASD children produced more tumor necrosis factor-alpha (TNF-alpha)/interleukin-12 (IL-12) than those obtained from control subjects with CMP, beta-lactoglobulin, and alpha-lactoalbumin, irrespective of objective GI symptoms. They also produced more TNF-alpha with gliadin, which was more frequently observed in the group with loose stools. PBMCs obtained from GI (-) ASD children produced more TNF-alpha/IL-12 with CMP than those from control subjects, but not with beta-lactoglobulin, alpha-lactoalbumin, or gliadin. Cytokine production with casein and soy were unremarkable.

CONCLUSION

A high prevalence of elevated TNF-alpha/IL-12 production by GI (+) ASD PBMCs with CMP and its major components indicates a role of NFH in GI symptoms observed in children with ASD.

Dysregulated innate immune responses in young children with autism spectrum disorders: their relationship to gastrointestinal symptoms and dietary intervention

OBJECTIVE

Our previous study indicated an association between cellular immune reactivity to common dietary proteins (DPs) and excessive proinflammatory cytokine production with endotoxin (lipopolysaccharide, LPS), a major stimulant of innate immunity in the gut mucosa, in a subset of autism spectrum disorder (ASD) children. However, it is unclear whether such abnormal LPS responses are intrinsic in these ASD children or the results of chronic gastrointestinal (GI) inflammation secondary to immune reactivity to DPs. This study further explored possible dysregulated production of proinflammatory and counter-regulatory cytokines with LPS in ASD children and its relationship to GI symptoms and the effects of dietary intervention measures.

METHODS

This study includes ASD children (median age 4.8 years) on the unrestricted (n = 100) or elimination (n = 77) diet appropriate with their immune reactivity. Controls include children with non-allergic food hypersensitivity (NFH; median age 2.9 years) on the unrestricted (n = 14) or elimination (n = 16) diet, and typically developing children (median age 4.5 years, n = 13). The innate immune responses were assessed by measuring production of proinflammatory (TNF-alpha, IL-1beta, IL-6, and IL-12) and counter-regulatory (IL-1ra, IL-10, and sTNFRII) cytokines by peripheral blood mononuclear cells (PBMCs) with LPS. The results were also compared to T-cell responses with common DPs and control T-cell mitogens assessed by measuring T-cell cytokine production.

RESULTS

ASD and NFH PBMCs produced higher levels of TNF-alpha with LPS than controls regardless of dietary interventions. However, only in PBMCs from ASD children with positive gastrointestinal (GI(+)) symptoms, did we find a positive association between TNF-alpha levels produced with LPS and those with cow's milk protein (CMP) and its major components regardless of dietary interventions. In the unrestricted diet group, GI(+) ASD PBMCs produced higher IL-12 than controls and less IL-10 than GI(-) ASD PBMCs with LPS. GI(+) ASD but not GI(-) ASD or NFH PBMCs produced less counter-regulatory cytokines with LPS in the unrestricted diet group than in the elimination diet group. There was no significant difference among the study groups with regard to cytokine production in responses to T-cell mitogens and other recall antigens.

CONCLUSION

Our results revealed that there are findings limited to GI(+) ASD PBMCs in both the unrestricted and elimination diet groups. Thus our findings indicate intrinsic defects of innate immune responses in GI(+) ASD children but not in NFH or GI(-) ASD children, suggesting a possible link between GI and behavioral symptoms mediated by innate immune abnormalities.

Relative carnitine deficiency in autism

A random retrospective chart review was conducted to document serum carnitine levels on 100 children with autism. Concurrently drawn serum pyruvate, lactate, ammonia, and alanine levels were also available in many of these children. Values of free and total carnitine (p < 0.001), and pyruvate (p = 0.006) were significantly reduced while ammonia and alanine levels were considerably elevated (p < 0.001) in our autistic subjects. The relative carnitine deficiency in these patients, accompanied by slight elevations in lactate and significant elevations in alanine and ammonia levels, is suggestive of mild mitochondrial dysfunction. It is hypothesized that a mitochondrial defect may be the origin of the carnitine deficiency in these autistic children.

Neurologic presentation of celiac disease

Celiac disease (CD) long has been associated with neurologic and psychiatric disorders including cerebellar ataxia, peripheral neuropathy, epilepsy, dementia, and depression. Earlier reports mainly have documented the involvement of the nervous system as a complication of prediagnosed CD. However, more recent studies have emphasized that a wider spectrum of neurologic syndromes may be the presenting extraintestinal manifestation of gluten sensitivity with or without intestinal pathology. These include migraine, encephalopathy, chorea, brain stem dysfunction, myelopathy, mononeuritis multiplex, Guillain-Barre-like syndrome, and neuropathy with positive antiganglioside antibodies. The association between most neurologic syndromes described and gluten sensitivity remains to be confirmed by larger epidemiologic studies. It further has been suggested that gluten sensitivity (as evidenced by high antigliadin antibodies) is a common cause of neurologic syndromes (notably cerebellar ataxia) of otherwise unknown cause. Additional studies showed high prevalence of gluten sensitivity in genetic neurodegenerative disorders such as hereditary spinocerebellar ataxia and Huntington's disease. It remains unclear whether gluten sensitivity contributes to the pathogenesis of these disorders or whether it represents an epiphenomenon. Studies of gluten-free diet in patients with gluten sensitivity and neurologic syndromes have shown variable results. Diet trials also have been inconclusive in autism and schizophrenia, 2 diseases in which sensitivity to dietary gluten has been implicated. Further studies clearly are needed to assess the efficacy of gluten-free diet and to address the underlying mechanisms of nervous system pathology in gluten sensitivity.

The effectiveness of secretin in the management of autism

Autism is a complex neurological disorder that severely impacts a child's ability to communicate and interact socially. Many treatments have attempted to alleviate the symptoms of autism, but with limited success. After reports of improvements in autistic children who received secretin, this hormone became popular as a possible treatment for autism. Since then, the interest in secretin has greatly increased, as well as the demand for secretin by parents of autistic children. However, there is still limited experimental evidence that supports its effectiveness. Many biological studies and clinical trials were conducted to test the effectiveness of secretin in treating autism. This review discusses the autistic disorder, instruments used in the trials, and reports the findings of some of these studies.

The insular lobe of Reil--its anatamico-functional, behavioural and neuropsychiatric attributes in humans--a review

There is considerable clinical and experimental research to explore the anatamico-functional correlations of the limbic lobe to establish its relevance in modern neuroscience. The insula being a pivotal structure in the concept of the greater limbic lobe, we have attempted to highlight in this review the topographical anatomy and development, the remarkable heterogeneity of the insular cortical architecture, the widespread multifaceted spectrum of functional connectivity patterns and how this is translated to its behavioural specialisation in humans. The insula serves as an intergration cortex for multimodal convergence of distributed neural networks such as the somesthetic-limbic, insulo-limbic, insulo-orbito-temporal and the prefrontal-striato-pallidal-basal forebrain. This provides the conceptual framework to facilitate functional and clinical considerations relevant to the various behavioural and neuropsychiatric disorders outlined in this review. The functional role of the insula in these disorders with particular reference to the current functional neuroimaging data has been also reviewed in this article.

Pilot Study of a Moderate Dose Multivitamin/Mineral Supplement for Children with Autistic Spectrum Disorder

OBJECTIVE

Determine the effect of a moderate dose multivitamin/mineral supplement on children with autistic spectrum disorder.

DESIGN

Randomized, double-blind, placebo-controlled 3-month study.

SUBJECTS

Twenty (20) children with autistic spectrum disorder, ages 3-8 years.

RESULTS

A Global Impressions parental questionnaire found that the supplement group reported statistically significant improvements in sleep and gastrointestinal problems compared to the placebo group. An evaluation of vitamin B(6) levels prior to the study found that the autistic children had substantially elevated levels of B6 compared to a control group of typical children (75% higher, p < 0.0000001). Vitamin C levels were measured at the end of the study, and the placebo group had levels that were significantly below average for typical children, whereas the supplement group had near-average levels.

DISCUSSION

The finding of high vitamin B(6) levels is consistent with recent reports of low levels of pyridoxal-5-phosphate and low activity of pyridoxal kinase (i.e., pyridoxal is only poorly converted to pyridoxal-5-phosphate, the enzymatically active form). This may explain the functional need for high-dose vitamin B(6) supplementation in many children and adults with autism.

Intestinal lymphocyte populations in children with regressive autism: evidence for extensive mucosal immunopathology

Inflammatory intestinal pathology has been reported in children with regressive autism (affected children). Detailed analysis of intestinal biopsies in these children indicates a novel lymphocytic enterocolitis with autoimmune features; however, links with cognitive function remain unclear. To characterize further, the nature and extent of this disease we examined the mucosal infiltrate using flow cytometry. Duodenal, ileal, and colonic biopsies were obtained from 52 affected children, 25 histologically normal, and 54 histologically inflamed, developmentally normal controls. Epithelial and lamina propria lymphocyte populations were isolated and examined by multicolor flow cytometry. Adjacent biopsies were assessed by semiquantitative histopathology. At all sites, CD3(+) and CD3(+)CD8(+) IEL as well as CD3(+) LPL were significantly increased in affected children compared with developmentally normal noninflamed control groups (p<0.01) reaching levels similar to inflamed controls. In addition, two populations--CD3(+)CD4(+) IEL and LP CD19(+) B cells--were significantly increased in affected children compared with both noninflamed and inflamed control groups including IBD, at all sites examined (p<0.01). Histologically there was a prominent mucosal eosinophil infiltrate in affected children that was significantly lower in those on a gluten- and casein-free diet, although lymphocyte populations were not influenced by diet. The data provide further evidence of a pan-enteric mucosal immunopathology in children with regressive autism that is apparently distinct from other inflammatory bowel diseases.

Secretin as a Treatment for Autism: A Review of the Evidence

Secretin is used in the United States for diagnosis of pancreatic gastrointestinal (GI) dysfunction and disease. Repeated therapeutic use has not been approved. Widespread interest in secretin as a treatment for autism followed media reports of behavioral improvements in an autistic child who received the hormone during a GI diagnostic procedure. International demand for secretin soared in the absence of experimental evidence of its efficacy for autism. This review presents a brief history of secretin's rise to popularity and summarizes research on secretin as a treatment for autism. Seventeen studies are reviewed comparing the effects of secretin forms, dosage levels, and dosing intervals on outcome measures with approximately 600 children. Twelve of 13 placebo-controlled studies failed to demonstrate the differential efficacy of secretin. Implications for advocating treatment in the absence of empirical evidence are discussed.

Secretin: hypothalamic distribution and hypothesized neuroregulatory role in autism

1. This study aims (1) to determine whether secretin is synthesized centrally, specifically by the HPA axis and (2) to discuss, on the basis of the findings in this and previous studies, secretin's possible neuroregulatory role in autism. 2. An immunocytochemical technique with single-cell resolution was performed in 12 age/weight-matched male rats pretreated with stereotaxic microinjection of colchicine (0.6 microg/kg) or vehicle into the lateral ventricle. Following 2-day survival, rats were anesthetized and perfused for immunocytochemistry. Brain segments were blocked and alternate frozen 30-microm sections incubated in rabbit antibodies against secretin, vasoactive intestinal peptide, glucagon, or pituitary-adenylate-cyclase-activating peptide. Adjacent sections were processed for Nissl stain. Preadsorption studies were performed with members of the secretin peptide family to demonstrate primary antibody specificity. 3. Specificity of secretin immunoreactivity (ir) was verified by clear-cut preadsorption control data and relatively high concentrations and distinct topographic localization of secretin ir to paraventricular/supraoptic and intercalated hypothalamic nuclei. Secretin levels were upregulated by colchicine, an exemplar of homeostatic stressors, as compared with low constitutive expression in untreated rats. 4. This study provides the first direct immunocytochemical demonstration of secretinergic immunoreactivity in the forebrain and offers evidence that the hypothalamus, like the gut, is capable of synthesizing secretin. Secretin's dual expression by gut and brain secretin cells, as well as its overlapping central distribution with other stress-adaptation neurohormones, especially oxytocin, indicates that it is stress-sensitive. A neuroregulatory relationship between the peripheral and central stress response systems is suggested, as is a dual role for secretin in conditioning both of those stress-adaptation systems. Colchicine-induced upregulation of secretin indicates that secretin may be synthesized on demand in response to stress, a possible mechanism of action that may underlie secretin's role in autism.

Focal-enhanced gastritis in regressive autism with features distinct from Crohn's and Helicobacter pylori gastritis

BACKGROUND

Immunohistochemistry allowed recent recognition of a distinct focal gastritis in Crohn's disease. Following reports of lymphocytic colitis and small bowel enteropathy in children with regressive autism, we aimed to see whether similar changes were seen in the stomach. We thus studied gastric antral biopsies in 25 affected children, in comparison to 10 with Crohn's disease, 10 with Helicobacter pylori infection, and 10 histologically normal controls. All autistic, Crohn's, and normal patients were H. pylori negative.

METHODS

Snap-frozen antral biopsies were stained for CD3, CD4, CD8, gammadelta T cells, HLA-DR, IgG, heparan sulphate proteoglycan, IgM, IgA, and C1q. Cell proliferation was assessed with Ki67.

RESULTS

Distinct patterns of gastritis were seen in the disease states: diffuse, predominantly CD4+ infiltration in H. pylori, and focal-enhanced gastritis in Crohn's disease and autism, the latter distinguished by striking dominance of CD8+ cells, together with increased intraepithelial lymphocytes in surface, foveolar and glandular epithelium. Proliferation of foveolar epithelium was similarly increased in autism, Crohn's disease and H. pylori compared to controls. A striking finding, seen only in 20/25 autistic children, was colocalized deposition of IgG and C1q on the subepithelial basement membrane and the surface epithelium.

CONCLUSIONS

These findings demonstrate a focal CD8-dominated gastritis in autistic children, with novel features. The lesion is distinct from the recently recognized focal gastritis of Crohn's disease, which is not CD8-dominated. As in the small intestine, there is epithelial deposition of IgG.

Developmental, behavioural and somatic factors in pervasive developmental disorders: preliminary analysis

OBJECTIVES

To ascertain the frequency of parental reporting of selected variables related to development, behaviour and physiology in subgroups diagnosed with pervasive developmental disorders (PDDs) and identify any significant intragroup differences.

DESIGN

Retrospective cross-sectional analysis of records of patients (n = 512) held on a computerized database with a chronological age between 3 and 11 years resident in the UK/Republic of Ireland and with a formal diagnosis of autism, Asperger syndrome (AS) or autism spectrum disorder (ASD).

METHODS

Non-parametric analysis (P > 0.01) of the frequency of specific variables for PDD subgroups reported by parents/primary caregiver. VARIABLES INCLUDED: timing of symptom onset, presence of skills acquired prior to symptom onset, indications of regression and regression events, current language, history of viral infections, history of ear problems, achievement of continence, current skin complaints, current bowel habits and adverse events at parturition.

RESULTS

Preliminary results showed general agreement with the principle diagnostic differences between the PDD subgroups with patients diagnosed with AS showing an increased frequency of skills acquired before symptom onset (two- to three-word phrase speech, toileting skills) and a decreased frequency of regression in acquired skills when compared with other PDD subgroups. Developmental milestones such as the achievement of bowel and bladder continence were also more frequently reported for the AS group. Infantile feeding problems defined as vomiting, reflux, colic and failure to feed were more frequently reported for the AS group as was a reported history of the bacterial skin infection impetigo. Results are discussed with reference to relationships between behavioural and somatic factors in PDD.

The Link Between Gastroenterology and Autism

References in the popular literature and media support a theory that gastrointestinal pathology may relate to autism. Parents often report their children as having gastrointestinal symptoms that surfaced about the same time autistic symptoms also appeared. The scope and range of information concerning autism available to the public is very extensive. Parents with children having autism are seen in gastroenterology and may request information related to the publicized connection between gastroenterology and autism. It is important for healthcare providers to be able to answer these questions based on the most recent research. The purpose of this article is to review an example of the current literature available to parents on this subject and compare this literature to relevant medical research.

Constipation with acquired megarectum in children with autism

OBJECTIVE

Recent evidence suggests that autistic children may have significant gastrointestinal symptoms. Although constipation occurs in 2% to 5% of healthy children, its clinical diagnosis is often difficult in children with behavioral disorders. We thus aimed to assess the prevalence of fecal loading in autistic children with gastrointestinal symptoms and to identify possible predictors of constipation.

METHODS

We studied abdominal radiographs of 103 autistic children (87 boys) who were referred for gastroenterological assessment, in comparison with 29 control radiographs from children who were referred to the emergency department, most with abdominal pain. Radiographs were scored independently, in blinded manner, by 4 pediatric gastroenterologists and a radiologist. The severity of constipation was determined using a validated index. Details of stool habit, abdominal pain, dietary history, and laxative use were obtained from case notes.

RESULTS

The incidence of constipation in the control subjects with abdominal pain was higher than reported for normal children. Despite this, moderate or severe constipation was more frequent in the autistic group than in the control subjects (36% vs 10%). Analysis of rectosigmoid loading showed more striking differences (54.4% of autistic children had moderate/severe loading or acquired megarectum compared with 24.1% of control subjects). Multivariate regression analysis showed consumption of milk to be the strongest predictor of constipation in the autistic group, whereas stool frequency, gluten consumption, soiling, and abdominal pain were not predictive of constipation.

CONCLUSIONS

Constipation is a frequent finding in children with gastrointestinal symptoms and autism, particularly in the rectosigmoid colon, often with acquired megarectum. The absence of any correlation between the clinical history and the degree of fecal impaction in autistic children confirms the importance of an abdominal radiograph in the assessment of their degree of constipation.

Purkinje cell vulnerability and autism: a possible etiological connection

Autism is a neurological disorder of unknown etiology. The onset of the abnormal growth and development within the brain is also not known. Current thought by experts in autism is that the time of onset is prenatal, occurring prior to 30 weeks gestation. However, autism comprises a heterogeneous population in that parents report either that their child was abnormal from birth, or that their child was developmentally normal until sometime after birth, at which time the child began to regress or deteriorate. Anecdotal reports suggest that some children with autism have significant illness or clinical events prior to the development of autistic symptoms. Conceivably, these children may become autistic from neuronal cell death or brain damage sometime after birth as result of insult. To support this theory is that marked Purkinje cell loss, the most consistent finding in the autistic disorder, can result from insult. Evidence suggests that the Purkinje cell is selectively vulnerable. This article discusses a theory that the selective vulnerability of the Purkinje cell may play a role in the etiology of autism, and suggests that a future direction in autism research may be to investigate the possibility of neuronal cell loss from insult as a cause of autism. Results of a small pilot survey are also discussed.

Intestinal cytokines in children with pervasive developmental disorders

OBJECTIVES

A relationship between autism and gastrointestinal (GI) immune dysregulation has been postulated based on incidence of GI complaints as well as macroscopically observed lymphonodular hyperplasia and microscopically determined enterocolitis in pediatric patients with autism. To evaluate GI immunity, we quantitatively assessed levels of proinflammatory cytokines, interleukin (IL)-6, IL-8, and IL-1beta, produced by intestinal biopsies of children with pervasive developmental disorders.

METHODS

Fifteen patients, six with pervasive developmental disorders and nine age-matched controls, presenting for diagnostic colonoscopy were enrolled. Endoscopic biopsies were organ cultured, supernatants were harvested, and IL-6, IL-8, and IL-1beta levels were quantified by ELISA. Tissue histology was evaluated by blinded pathologists.

RESULTS

Concentrations of IL-6 from intestinal organ culture supernatants of patients with pervasive developmental disorders (median 318.5 pg/ml, interquartile range 282.0-393.0 pg/ml) when compared with controls (median 436.9 pg/ml, interquartile range 312.6-602.5 pg/ml) were not significantly different (p = 0.0987). Concentrations of IL-8 (median 84,000 pg/ml, interquartile range 16,000-143,000 pg/ml) when compared with controls (median 177,000 pg/ml, interquartile range 114,000-244,000 pg/ml) were not significantly different (p = 0.0707). Concentrations of IL-1beta (median 0.0 pg/ml, interquartile range 0.0-94.7 pg/ml) when compared with controls (median 0.0 pg/ml, interquartile range 0.0-60.2 pg/ml) were not significantly different (p = 0.8826). Tissue histology was nonpathological for all patients.

CONCLUSIONS

We have demonstrated no significant difference in production of IL-6, IL-8, and IL-1beta between patients with pervasive developmental disorders and age-matched controls. In general, intestinal levels of IL-6 and IL-8 were lower in patients with pervasive developmental disorders than in age-matched controls. These data fail to support an association between autism and GI inflammation.

Children with autistic spectrum disorders. I: comparison of placebo and single dose of human synthetic secretin

AIMS

To examine the effect of a single dose of human synthetic secretin (HSS) on behaviour and communication in children with autism spectrum disorder (ASD) using an objective measure of communication and social reciprocity and standardised rating scales.

METHODS

Randomised, crossover, double blind, and placebo controlled trial of a single intravenous dose of human synthetic secretin (HSS) 2 CU/kg. The 62 subjects (3-8 years) were assigned to group 1 (saline placebo/HSS) or group 2 (HSS/saline placebo). Diagnosis was confirmed by ADI-R (Autism Diagnostic Interview-Revised) algorithm. Severity of symptoms was rated using the CARS (Childhood Autism Rating Scale). Outcome measures included Communication and Symbolic Behavior Scale (CSBS), Ritvo Real-life Rating Scale, weekly Global Rating Scale (GBRS) by parents and teachers, and daily log of gastrointestinal symptoms. The communication subscale of the CSBS, specifying communication function, reciprocity, and social-affective signalling was videotaped and scored by a blinded, trained observer.

RESULTS

Sixty one children completed the study. After randomisation, there were no significant differences in gender, race, age, and parent and teacher GBRS and Ritvo Scale between the two groups. Compared with placebo, secretin treatment was not associated with significant improvement of CSBS standard scores from baseline to 2 or 4 weeks post-infusion. Five children showed clinical improvement in standard scores: two after HSS and three after placebo. There were no significant changes in gastrointestinal symptoms after HSS or saline placebo.

CONCLUSIONS

A single dose of intravenous human secretin is not effective in changing behaviour and communication in children with ASD when compared to placebo.

Prevalence of chronic gastrointestinal symptoms in children with autism and autistic spectrum disorders

The purpose of this study was to estimate the prevalence of chronic gastrointestinal symptoms in a general population of children with autism or autistic spectrum disorder (ASD). The study site was a clinic specializing in ASD in a large pediatric medical center serving a 10 county area in the midwestern USA. In a sample of 137 children, age 24-96 months, classified as having autism or ASD by the Autism Diagnostic Observation Schedule-Generic, 24 percent had a history of at least one chronic gastrointestinal symptom. The most common symptom was diarrhea, which occurred in 17 percent. There was no association between chronic gastrointestinal symptoms and a history of developmental regression. The potential phenotypic association between autism and gastrointestinal symptoms is discussed.

Intestinal pathophysiology in autism

Autism is a life-long developmental disorder affecting as many as 1 in 500 children. The causes for this profound disorder are largely unknown. Recent research has uncovered pathology in the gastrointestinal tract of autistic children. The pathology, reported to extend from the esophagus to the colon, is described here along with other studies pointing to a connection between diet and the severity of symptoms expressed in autism. The evidence that there is impaired intestinal permeability in autism is reviewed, and various theories are discussed by which a leaky gut could develop. Lastly, some possible ways in which impaired gastrointestinal function might influence brain function are discussed.

Does the MMR vaccine and secretin or its receptor share an antigenic epitope?

In a subgroup of children with autism-spectrum like conditions symptoms seem to appear as a 'regression' (in normal development). It has been postulated that the onset of such autistic symptoms may involve an autoimmune response against the central nervous system and that the antigenic determinant could possibly be gastrointestinal in origin. It has been suggested that the presence of the measles virus and 'autistic enterocolitis' demonstrates the possibility that the MMR triple vaccine may be mediating the inflammation with possible production of antibodies against the virus containing vaccine. Such an antibody may share antigenic determinant to molecules found in the gut. We propose that this may be secretin or its receptor, found in the gut as well as in the central nervous system. The antibody response to the gut may also conceivably occur in the brain at a critical time in development. The modulation of development by secretin may be a static event possibly occurring at a specific time in early childhood development and if it involves an autoimmune response then a disruption in development may result. These hypothesized events can only occur if the MMR vaccine shares antigenic determinants that resemble secretin or any of its receptor types and remains to be studied.

Childhood autism: a circuit syndrome?

BACKGROUND

Autism is a disorder that can lead to life-long disability. Currently, the etiology of autism is unknown, and although there are treatments for some of the behavioral abnormalities, there is no cure.

REVIEW SUMMARY

While this article will review the clinical, anatomic, and pathologic features seen in autism, the primary focus will be to present a new and provocative unifying theory regarding the underlying mechanisms causing this disorder. Current research advances, some controversial, will be discussed, and a novel definition of autism as a "circuit syndrome" will be presented. The work elaborated here will tie many of the disparate findings together, based on the idea that autism arises from abnormalities of the cerebellolimbic circuitry. Some of the more alternative theories of autism, such as mercury toxicity, linkage to the measles, mumps, and rubella vaccine, and the use of secretin will be discussed. Finally, pharmacologic treatment options will be reviewed.

CONCLUSIONS

Autism is not single disorder but represents dysfunction of the cerebellolimbic circuitry that can arise from many different etiologies.

Can the pathophysiology of autism be explained by the nature of the discovered urine peptides?

Opioid peptides derived from food proteins (exorphins) have been found in urine of autistic patients. Based on the work of several groups, we try to show that exorphins and serotonin uptake stimulating factors may explain many of the signs and symptoms seen in autistic disorders. The individual symptoms ought to be explainable by the properties and behavioural effects of the found peptides. The data presented form the basis of an autism model, where we suggest that exorphins and serotonin uptake modulators are key mediators for the development of autism. This may be due to a genetically based peptidase deficiency in at least two or more peptidases and, or of peptidase regulating proteins made manifest by a dietary overload of exorphin precursors such as by increased gut uptake.

The role of cellular secretion in autism spectrum disorders: a unifying hypothesis

This paper outlines the possibility that disruption of cell-to-cell biochemical signaling activates a cascade of events resulting in a diverse spectrum of behavioral and biological symptoms associated with autism spectrum disorders.

Lack of benefit of intravenous synthetic human secretin in the treatment of autism

The objective of this study was to determine if an intravenous infusion of synthetic human secretin improves language and behavioral symptoms in children with autism. Forty-two children with the diagnosis of autism were randomized to one of two groups in this double-blind cross-over trial. One group received 2 IU/kg of intravenous synthetic human secretin at the first visit, followed by an equal volume of intravenous saline placebo at week 6. The other group received treatments in the reverse order. All children were evaluated at weeks 1, 3, 6, 9, and 12 with standardized assessments of language, behavior, and autism symptomatology. There were no significant differences in the mean scores on any measure of language, behavior, or autism symptom severity after treatment with secretin compared to treatment with placebo. The results of this study do not support secretin as a treatment for autism.

What may be the anatomical basis that secretin can improve the mental functions in autism?

Autism was first described and characterized as a behavioral disorder more than 50 years ago. The major abnormality in the central nervous system is a cerebellar atrophy. The characteristic histological sign is a striking loss or abnormal development in the Purkinje cell count. Abnormalities were also found in the limbic system, in the parietal and frontal cortex, and in the brain stem. The relation between secretin and autism was observed 3 years ago. Clinical observations by Horváth et al. [J. Assoc. Acad. Minor. Physicians 9 (1998) 9] supposed a defect in the role of secretin and its receptors in autism. The aim of the present work was to study the precise localization of secretin immunoreactivity in the nervous system using an immunohistochemical approach. No secretin immunoreactivity was observed in the forebrain structures. In the brain stem, secretin immunoreactivity was observed in the mesencephalic nucleus of the trigeminal nerve, in the superior olivary nucleus, and in scattered cells of the reticular formation. The most intensive secretin immunoreactivity was observed in the Purkinje cells of the whole cerebellum and in some of the neurons of the central cerebellar nuclei. Secretin immunoreactivity was also observed in a subpopulation of neurons in the primary sensory ganglia. This work is the first immunohistochemical demonstration of secretin-immunoreactive elements in the brain stem and in primary sensory ganglia.

A randomized, double-blind, placebo-controlled trial of porcine versus synthetic secretin for reducing symptoms of autism

OBJECTIVE

To compare the effects of a single dose of biologic and synthetic porcine secretin to placebo on a variety of autism symptoms.

METHOD

Eighty-five children with autism without other medical conditions and not taking other psychotropic medications participated (ages between 3 and 12 years, mean IQ = 55). Children were grouped into trios matched by age and communication level and then randomly assigned to one of three treatment groups: biologic secretin (2 CU/kg), synthetic secretin (0.4 microg/kg), and placebo. Measures collected 1 week before and 4 weeks after infusion included autism symptoms, language skills, and problem behaviors, gathered from parents, teachers, and investigators, who were all blind to treatment. Two-factor, repeated-measures analyses of variance (3 treatment levels by 2 repeated measures, pre- and postinfusion) were used to examine efficacy.

RESULTS

Direct observation measures did not show change over time related to secretin. Parent reports showed an overall reduction of symptom severity for all treatment groups, including the placebo group. One teacher-report measure showed decreases in autism symptoms in the placebo and synthetic secretin groups.

CONCLUSIONS

No evidence that either biologic or synthetic secretin provided amelioration of symptoms beyond placebo was observed. This held true when children with and without gastrointestinal problems were examined separately.

Autistic disorder and gastrointestinal disease

Autistic disorder is a pervasive developmental disorder manifested in the first 3 years of life by dysfunction in social interaction and communication. Many efforts have been made to explore the biologic basis of this disorder, but the etiology remains unknown. Recent publications describing upper gastrointestinal abnormalities and ileocolitis have focused attention on gastrointestinal function and morphology in these children. High prevalence of histologic abnormalities in the esophagus, stomach, small intestine and colon, and dysfunction of liver conjugation capacity and intestinal permeability were reported. Three surveys conducted in the United States described high prevalence of gastrointestinal symptoms in children with autistic disorder. Treatment of the digestive problems may have positive effects on their behavior.

Small intestinal enteropathy with epithelial IgG and complement deposition in children with regressive autism

We have reported lymphocytic colitis in children with regressive autism, with epithelial damage prominent. We now compare duodenal biopsies in 25 children with regressive autism to 11 with coeliac disease, five with cerebral palsy and mental retardation and 18 histologically normal controls. Immunohistochemistry was performed for lymphocyte and epithelial lineage and functional markers. We determined the density of intraepithelial and lamina propria lymphocyte populations, and studied mucosal immunoglobulin and complement C1q localisation. Standard histopathology showed increased enterocyte and Paneth cell numbers in the autistic children. Immunohistochemistry demonstrated increased lymphocyte infiltration in both epithelium and lamina propria with upregulated crypt cell proliferation, compared to normal and cerebral palsy controls. Intraepithelial lymphocytes and lamina propria plasma cells were lower than in coeliac disease, but lamina propria T cell populations were higher and crypt proliferation similar. Most strikingly, IgG deposition was seen on the basolateral epithelial surface in 23/25 autistic children, co-localising with complement C1q. This was not seen in the other conditions. These findings demonstrate a novel form of enteropathy in autistic children, in which increases in mucosal lymphocyte density and crypt cell proliferation occur with epithelial IgG deposition. The features are suggestive of an autoimmune lesion.

Methylsulfonylmethane observed by in vivo proton magnetic resonance spectroscopy in a 5-year-old child with developmental disorder: effects of dietary supplementation

Proton magnetic resonance spectroscopy (MRS) revealed a distinct resonance at 3.15 ppm in the brain of a 5-year-old male diagnosed with autism. The resonance assignment is attributable to ingestion of methylsulfonylmethane (MSM) as a dietary supplement. Glucosamine with MSM is marketed as a source of dietary sulfur and treatment of joint pain. Recognition of this chemical on brain proton MRS as an exogenous compound is necessary to avoid confusion as a pathologic metabolite of pediatric metabolic disease.

Secretin as a neuropeptide

The role of secretin as a classical hormone in the gastrointestinal system is well-established. The recent debate on the use of secretin as a potential therapeutic treatment for autistic patients urges a better understanding of the neuroactive functions of secretin. Indeed, there is an increasing body of evidence pointing to the direction that, in addition to other peptides in the secretin/glucagon superfamily, secretin is also a neuropeptide. The purpose of this review is to discuss the recent data for supporting the neurocrine roles of secretin in rodents. By in situ hybridization and immunostaining, secretin was found to be expressed in distinct neuronal populations within the cerebellum and cerebral cortex, whereas the receptor transcript was found throughout the brain. In the rat cerebellum, secretin functions as a retrograde messenger to facilitate GABA transmission, indicating that it can modulate motor and other functions. In summary, the recent data support strongly the neuropeptide role of secretin, although the secretin-autism link remains to be clarified in the future.

Secretin treatment for autistic disorder: a critical analysis

We assessed evidence of the effects of secretin on behavior in individuals with autistic disorder. Articles were obtained through a MEDLINE search of the English-language literature from January 1966-November 2001; all investigations and case reports on the topic were included. Press releases obtained from the World Wide Web also were included. Secretin, a gastrointestinal hormone, is suggested to improve autistic symptoms, particularly social function and communication. Two formulations, porcine and synthetic human secretin, were evaluated in humans. A small body of literature and popular belief in autistic disorder communities supported the agent's efficacy. A number of controlled clinical trials did not show improvement in autistic symptoms with secretin compared with placebo, possibly indicating no role for the drug in autistic disorder.

Efficacy of porcine secretin in children with autism and pervasive developmental disorder

Secretin, a gastrointestinal (GI) hormone, was reported in a preliminary study to improve language and behavior in children with autism/pervasive developmental disorder (PDD) and chronic diarrhea. To determine the efficacy of secretin, we completed a double-blind, placebo-controlled, crossover (3 weeks) study in children with autism/PDD and various GI conditions using a single dose of intravenous porcine secretin. Children with chronic, active diarrhea showed a reduction in aberrant behaviors when treated with the secretin but not when treated with the placebo. Children with no GI problems are unaffected by either secretin or placebo. The improvement seen with secretin in children with autism/PDD and chronic diarrhea suggests that there may be a subtype of children with autism/PDD who respond to secretin.

Autism and gastrointestinal symptoms

Autism is a collection of behavioral symptoms characterized by dysfunction in social interaction and communication in affected children. It is typically associated with restrictive, repetitive, and stereotypic behavior and manifests within the first 3 years of life. The cause of this disorder is not known. Over the past decade, a significant upswing in research has occurred to examine the biologic basis of autism. Recent clinical studies have revealed a high prevalence of gastrointestinal symptoms, inflammation, and dysfunction in children with autism. Mild to moderate degrees of inflammation were found in both the upper and lower intestinal tract. In addition, decreased sulfation capacity of the liver, pathologic intestinal permeability, increased secretory response to intravenous secretin injection, and decreased digestive enzyme activities were reported in many children with autism. Treatment of digestive problems appears to have positive effects on autistic behavior. These new observations represent only a piece of the unsolved autism "puzzle" and should stimulate more research into the brain-gut connection.

Biochemical aspects in autism spectrum disorders: updating the opioid-excess theory and presenting new opportunities for biomedical intervention

Autism is a lifelong condition usually described as affecting social, cognitive and imaginative abilities. For many years, parents and some professionals have observed that in concordance with the behavioural and psychological symptoms of the condition, there are a number of physiological and biochemical correlates which may also be of relevance to the syndrome. One area of interest that encompasses many of these observations is the opioid-excess theory of autism. The main premise of this theory is that autism is the result of a metabolic disorder. Peptides with opioid activity derived from dietary sources, in particular foods that contain gluten and casein, pass through an abnormally permeable intestinal membrane and enter the central nervous system (CNS) to exert an effect on neurotransmission, as well as producing other physiologically-based symptoms. Numerous parents and professionals worldwide have found that removal of these exogenously derived compounds through exclusion diets can produce some amelioration in autistic and related behaviours. There is a surprisingly long history of research accompanying these ideas. The aim of this paper is to review the accompanying evidence in support of this theory and present new directions of intervention as a result of it.

Pathophysiology of autism: current opinions

Research on the neurochemical aspects of the pathophysiology of autism is still increasing and publications are abundant. In this paper we reviewed significant data from the last decade and recent research results from our center. We focused on molecules influencing the central nervous system (CNS) and consecutively responsible for typical autistic behavior. We highlighted the mutual relationship between the serotonergic, immunological and endocrinological system and the interaction of these three pivotal systems with predisposing (genetic)and external (pre-, peri- and postnatal) conditions and xenobiotics. We stressed the influence of age, pubertal stage, sex, race and IQ on biological data. There is growing evidence that the complexity and variability of those interactions might be responsible for the heterogeneity of behavioral phenotypes and biological findings in Autism. Genetic, neuroanatomical and neurophysiological data were mentioned according their relevance to neurochemical opinions.

Review article: the concept of entero-colonic encephalopathy, autism and opioid receptor ligands

There is growing awareness that primary gastrointestinal pathology may play an important role in the inception and clinical expression of some childhood developmental disorders, including autism. In addition to frequent gastrointestinal symptoms, children with autism often manifest complex biochemical and immunological abnormalities. The gut-brain axis is central to certain encephalopathies of extra-cranial origin, hepatic encephalopathy being the best characterized. Commonalities in the clinical characteristics of hepatic encephalopathy and a form of autism associated with developmental regression in an apparently previously normal child, accompanied by immune-mediated gastrointestinal pathology, have led to the proposal that there may be analogous mechanisms of toxic encephalopathy in patients with liver failure and some children with autism. Aberrations in opioid biochemistry are common to these two conditions, and there is evidence that opioid peptides may mediate certain aspects of the respective syndromes. The generation of plausible and testable hypotheses in this area may help to identify new treatment options in encephalopathies of extra-cranial origin. Therapeutic targets for this autistic phenotype may include: modification of diet and entero-colonic microbial milieu in order to reduce toxin substrates, improve nutritional status and modify mucosal immunity; anti-inflammatory/immunomodulatory therapy; and specific treatment of dysmotility, focusing, for example, on the pharmacology of local opioid activity in the gut.

Genetic and immunologic considerations in autism

According to recent epidemiological surveys, autistic spectrum disorders have become recognized as common childhood psychopathologies. These life-lasting conditions demonstrate a strong genetic determinant consistent with a polygenic mode of inheritance for which several autism susceptibility regions have been identified. Parallel evidence of immune abnormalities in autistic patients argues for an implication of the immune system in pathogenesis. This review summarizes advances in the molecular genetics of autism, as well as recently emerging concerns addressing the disease incidence and triggering factors. The neurochemical and immunologic findings are analyzed in the context of a neuroimmune hypothesis for autism. Studies of disorders with established neuroimmune nature indicate multiple pathways of the pathogenesis; herein, we discuss evidence of similar phenomena in autism.

Genomic screen and follow-up analysis for autistic disorder

Autistic disorder (AutD) is a neurodevelopmental disorder characterized by significant impairment in social, communicative, and behavioral functioning. A genetic basis for AutD is well established with as many as 10 genes postulated to contribute to its underlying etiology. We have completed a genomic screen and follow-up analysis to identify potential AutD susceptibility loci. In stage one of the genome screen, 52 multiplex families (two or more AutD affected individuals/family) were genotyped with 352 genetic markers to yield an approximately 10 centimorgan (cM) grid, inclusive of the X chromosome. The selection criterion for follow-up of interesting regions was a maximum heterogeneity lod score (MLOD) or a maximum nonparametric sib pair lod score (MLS) of at least 1.0. Eight promising regions were identified on chromosomes 2, 3, 7, 15, 18, 19, and X. In the stage two follow-up study we analyzed an additional 47 multiplex families (total=99 families). Regions on chromosomes 2, 3, 7, 15, 19, and X remained interesting (MLOD> or =1.0) in stage two analysis. The peak lod score regions on chromosomes 2, 7, 15, 19, and X overlap previously reported peak linkage areas. The region on chromosome 3 is unique.

Secretin and sleep in children with autism

The objectives of this pilot study were 1) to examine possible effects of secretin infusions on sleep-wake state organization in children with autism, and 2) to assess the feasibility of home recordings using time-lapse videosomnography in children with autism. Participants were a subset of subjects from two double blind, placebo-control, multi-center clinical trials. One trial, the UC Irvine study, assessed the effects of porcine secretin vs. saline infusions on children's behavior, language and IQ. The UC Davis trial assessed the effects of synthetic human secretin vs. saline infusions on behavior, language and gastrointestinal function. The sleep study enrolled some of the children from each of the two trials to observe possible secretin effects on sleep. To examine sleep, the UC Irvine trial used the Children's Sleep Habits Questionnaire and daily sleep diaries, whereas the UC Davis study used home-recorded time-lapse videosomnography. Because of the small sample size, the results from both trials are preliminary. They suggest that secretin, porcine or synthetic, does not improve sleep-wake state organization dramatically.

Anterior insular cortex: linking intestinal pathology and brain function in autism-spectrum subgroups

Autism includes deficits in communications skills and is associated with intestinal pathology. Numerous parents and some physicians report that an autistic child's attention and language improve in response to treatments which eliminate certain dietary antigens and/or which improve intestinal health. For at least some autism-spectrum children, the link between intestinal pathology, attention, and language may derive from shared neuroanatomic pathways within the anterior insular cortex (aIC); from a neurotrophic virus such as herpes simplex (HSV) migrating within afferents to the insular cortex; and/or from synaptic exhaustion in the aIC as induced by chronically inappropriate neuronal activity in the enteric nervous system and/or its vagal efferents.