Autism is a complex condition which includes a spectrum of neurodevelopmental disorders now known as autism spectrum disorders or ASD. Onset of the condition occurs before 3 years of age. Children with autism have impaired social and communicative abilities, as well as a range of behavioral symptoms such as attention deficit disorder, repetitive behaviors and emotional outbursts. Autistic children have social and language impairment and usually have learning disabilities. Moreover, many autistic children suffer from anxiety, depression and other psychiatric illnesses. Approximately 85% of children diagnosed as autistic also have a range of gastrointestinal disorders and symptoms including diarrhea, constipation, bloating and abdominal pain.
The prevalence of autism has increased more than 10-fold in the last 20 years, from 5 per 10,000 children to a massive 65 per 10,000 today. Autism is thought to be genetically based, but triggered by environmental factors.
Many theories abound as to the causes of autism, including toxic adjuvants such as mercury and aluminum in childhood vaccines, involvement of various hormones including secretin and, most recently, a possible link with gluten sensitivity. Currently, there is no known or accepted cure for autism. Treatment consists of a program of developmental therapies, educational programs and behavioral treatment.
In the same way that a gut-brain connection seems to exist in celiac disease (CD), a gut-brain connection may also exist in autism and autistic traits are sometimes found in children with CD. Some researchers think that autistic children could be gluten sensitive and that their symptoms could improve with a gluten-free diet.
As well as gluten, another protein that may lead to neurodevelopmental problems is the protein casein. Casein, which is the main protein in milk, breaks down into a peptide called casomorphin. Some studies have suggested this protein could also be involved in the development of autism.
Both gluten and casein have been implicated in the ‘leaky gut hypothesis’, the thinking behind which is as follows: Following irritation and inflammation of the digestive tract such as that which takes place in celiac disease, the intestinal lining begins to degenerate and gaps form between the tight junction cells which normally act as barrier, preventing prevent toxic substances from entering the bloodstream. When this barrier is damaged, particles of food, toxins and pathogens are able to squeeze through the intestinal lining. It is possible that breakdown products of protein (peptides) from wheat and milk could be absorbed as a result of this intestinal permeability. These opioid peptides then enter the bloodstream and spinal fluid and some can cross the blood brain barrier into the brain. This affects the opiate system and neurotransmission within the nervous system. Some researchers believe that these intestinal barrier defects could play a crucial role in the development of childhood developmental disorders such as autism. Studies of a small group of children with autism but with no gastrointestinal symptoms found that half of them nevertheless had high intestinal permeability.
It has been found that food exclusion diets which exclude gluten and/or casein often lead to improvements in autistic symptoms. Many parents have reported noticeable improvements in their child’s social abilities following adoption of a gluten and casein free diet. In a few cases, dietary intervention has been found to completely eradicate both the child’s gastrointestinal symptoms and behavioral difficulties.
Most research studies of food exclusion diets exclude both gluten and casein at the same time, and long-term studies with large numbers of patients are few and far between. However, following a 2-year study in Denmark on the adoption of a gluten and casein-free diet for 72 children diagnosed with autism, significant improvement in core autistic behaviors were evident in the children as early as 8 months into the study. These included improvements in repetitive behaviors, attention span, communication and social interaction.
Leaky gut syndrome has also been implicated in many other disorders such as fibromyalgia, chronic fatigue syndrome, arthritis, diabetes and other autoimmune diseases. Hopefully, future large-scale studies will go further in elucidating this fascinating connection.