Autism: a rising problem

Original Internist,  Sept, 2003  by Nikhil V. Jathar,  Vithal S. Jathar

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Introduction

Autism is a developmental disability characterized by impairment in social interaction and communication skills. It falls under the broader umbrella of pervasive developmental disorders and is commonly referred to as autistic spectrum disorder (ASD) because its characteristics are often observed in different combinations with varying degrees of severity. The medical community's urgency to increase awareness, diagnosis, and treatment is driven primarily by the fact that ASD afflicts children. ASD is believed to be present at birth with signs and symptoms becoming apparent around the age of three. Afflicted children are often socially withdrawn and behave in compulsive and ritualistic ways characterized by bizarre and uncontrollable mannerisms. Other symptoms include lack of normal speech patterns, inability to concentrate, and avoidance of eye contact.

The number of confirmed cases of ASD has increased almost three-fold in the last decade. It is unclear whether this trend is due to increased incidence or diagnosis. In 2001, the Centers for Disease Control and Prevention estimated the incidence in the US to be 2-6 individuals out of 1,000 with approximately 1.0-1.5 million individuals with some form of autism. Although ASD does not appear to be biased across socioeconomic or ethnic boundaries, it is four times more prevalent in boys than in girls. Global incidence is believed to be similar to US estimates thus implying 25-35 million cases worldwide. The incidence of ASD is now five times more common than Down's syndrome and three times that of juvenile diabetes

Families coping with this devastating disorder are searching for answers about its causes, diagnosis, prevention, and treatment. Various hypotheses promulgated about the mechanism of action for ASD include the role of metabolic, biochemical, and physiological factors. This article addresses the potential for certain metabolic dysfunctions to lead to biochemical imbalances in the central nervous system (CNS) of patients with autism. We also investigate the physiological maladies dealing with poor intestinal health which serve to exacerbate the effects of both metabolic and biochemical dysfunction. These dysfunctions are tied to "The Peptide Theory" which suggests that improper metabolism of foods such as milk and wheat leads to the accumulation of opioid like peptides in the intestinal lumen. These peptides permeate the intestinal gut wall and eventually migrate to certain nuclei in the CNS where they exert trophic effects that manifest as symptoms associated with autism. Furthermore, good intestinal health is critical to maintaining proper gut wall permeability. When intestinal health is compromised, the potential for increased permeability can lead to heightened transport of these peptides from the intestinal lumen to the CNS. This article elucidates the potential for bacterial and fungal overgrowth to act as an alert signal for assessing and monitoring the patient's intestinal health.

Based on this etiological framework, we propose a panel of diagnostic tests that can be used to screen for various biomarkers in patients with autism. These diagnostic tests include antibodies against various food antigens, such as milk, wheat, eggs, and nuts and also certain bacterial and fungal species found in the intestinal lumen. Consequently, we report the measured levels of these antibodies in 49 children with autism ranging in age from 1-16 (Figures 1-3). This panel of diagnostic tests can subsequently be used to implement effective biomedical remedies targeted at ameliorating ASD symptoms. These remedies include dietary interventions, such as casein-free/gluten-free diets, yeast-free diets, and probiotics. Restriction diets target the metabolic and biochemical pathways, while probiotics are effective for re-establishing proper intestinal health.

Peptide Theories and Autism Spectrum Disorders

The connection between abnormal levels of opioid like peptides and ASD was first reported in the early 1980s. Pursuant to these initial findings vast research has been conducted investigating the link between ASD and these peptides. Collectively, this research has identified a strong correlation between the incidence of ASD and abnormally high levels of the peptides caseomorphin and gluteomorphin. This correlation suggests a possible causal link between an individual's dietary habits and their ASD symptoms. Casein, present in milk and dairy products, and gluten, commonly found in wheat and cereal products, when consumed, are broken down into amino acids by the body's natural metabolic processes. Certain enzymatic dysfunctions can disrupt this metabolism thus resulting in the accumulation of caseomorphin and gluteomorphin in the intestinal lumen. Other studies have shown that increased intestinal permeability commonly found in patients with autism contributes to increased protein uptake. In ASD cases, this leads to increased uptake and transport of opioid like peptides to the central nervous systems (CNS) where these substances eventually exert trophic effects on key nuclei of the brain and also affect CNS maturation. These peptides, once transported to the brain, modulate various neurotransmitter systems which may help explain the causal link between these peptides and the behavioral traits exhibited by patients with autisms. This mechanism is further supported by the observed similarities in behavior of children with ASD and animals and people exposed to opioid drugs. (4)