Autism and the Digestive System: Autism Is Multi-Factorial but an Intriguing Clue Lies in the Gut

Article excerpt

Autism spectrum disorders (ASD) are a rapidly increasing problem in western society. Autism is a spectrum of severe neurodevelopmental disorders, frequently consisting of profound language impairment, repetitive motor behaviors, impaired socialization, sensory disturbances, severely restricted interests, and self-injury. Seizure disorders also frequently accompanies autism. The prevalence of autism is now 1 in 150. This alarming increase, rising from between seven and 20 per 10,000 just a few decades ago, cannot be accounted for merely by increased surveillance.

Autism was originally thought to be due to environmental influences such as poor parenting. However, recent research from human autopsies, brain imaging, and clinical biochemistry are now seeing autism as a definable systemic disorder involving a number of factors that may affect brain development both preor post-natally. Neuropathological work being pioneered by Margaret Bauman and recent imaging studies by Martha Herbert at Harvard University have shown subtle disorders in brain development, involving language, facial expression, movement, and social behavior.

Studies suggest that persons with autism have enlarged brain size, particularly in the first few years of life. A recent neuropathological study by Carlos Pardo at Johns Hopkins University has revealed evidence of inflammatory processes in the brains of young patients as well as adult patients.

The cause of autism is as yet unknown and is likely due to many factors. Genetic factors undoubtedly play a major role. The relative risk of first degree relatives is 100 fold higher, and concordance in identical twins is 60 percent. However, even though genetics is suspected as a major factor, a purely genetic link remains elusive and is over-simplistic. Indeed, factors in the uterus may also play a role, given the many similarities with neurological abnormalities from intrauterine exposure to ethanol, valproic acid, terbutaline, or thalidomide, and prenatal infections. Supportive of this notion are studies that have examined the effects of early prenatal exposure to these agents in rodents. Administration of these agents near the time of neural tube closure have shown brain structural changes and altered social behavior similar to aspects of human autism.

Anecdotal reports from parents and other family members note that the symptoms first occur after apparently normal development in the first few years of life, often following either acute gastrointestinal infections, upper respiratory infections, or vaccination for childhood viral diseases. Regarding vaccination, the link between autism and the Thimersol-containing measles, mumps, rubella vaccine (MMR) has received tremendous media attention but has not been proven. This raises the strong possibility that other factors during early childhood may be involved. The current consensus is that autism may comprise a family of disorders, resulting from genetic sensitivity to intrauterine or early post-natal exposure to a variety of environmental toxic or infective factors.

A link between autism and seizure disorders is great and may be under-reported. Autism is a major component in tuberous sclerosis, which also results in severe cortical development problems and seizure disorder, and the Landau-Kleffner syndrome of acquired aphasia and seizure. In particular, the symptomology of non-convulsive seizures resembles many aspects found in autism, including aggression, repetitive motor activity, and inattention.

[ILLUSTRATION OMITTED]

Many investigators are looking at autism as a general metabolic disorder involving environmental factors such as metals or environmental organic compounds or, more likely, a genetic sensitivity to these compounds in specific sub populations. These may result in increased oxidative stress through cumulative production of reactive oxygen free radicals and the resultant inflammation which cause widespread damage to the central nervous system both before and after birth. …

Oops!

An unknown error has occurred. Please click the button below to reload the page. If the problem persists, please try again in a little while.