Written by Stephen M. Edelson, Ph.D.
Center for the Study of Autism, Salem, Oregon

There is a great deal of evidence that a form of yeast, candida (rhymes with "Canada") albicans, may cause autism and may exacerbate many behavior and health problems in autistic individuals, especially those with late-onset autism.

Scenario. Candida albicans belongs to the yeast family and is a single-cell fungus. This form of yeast is located in various parts of the body including the digestive tract. Generally speaking, benign microbes limit the amount of yeast in the intestinal tract, and thus, keep the yeast under control. However, exposure to antibiotics, especially repeated exposure, can destroy these microbes. This can result in an overgrowth of candida albicans. When the yeast multiplies, it releases toxins in the body; and these toxins are known to impair the central nervous system and the immune system.

Some of the behavior problems which have been linked to an overgrowth of candida albicans include: confusion, hyperactivity, short attention span, lethargy, irritability, and aggression. Health problems can include: headaches, stomachaches, constipation, gas pains, fatigue, and depression. These problems are often worse during damp and/or muggy days and in moldy places. Additionally, exposure to perfumes and insecticides can worsen the condition.

Dr. William Shaw has been conducting important research on yeast and its effects on autistic individuals. He recently discovered unusual microbial metabolites in the urine of autistic children who responded remarkably well to anti-fungal treatments. Dr. Shaw and his colleagues observed a decrease in urinary organic acids as well as decreases in hyperactivity and self-stimulatory, stereotyped behavior; and increases in eye contact, vocalization, and concentration.

There are many safe methods to treat yeast overgrowth, such as taking nutritional supplements which replenish the intestinal tract with 'good' microbes (e.g., acidophilus) and/or taking anti-fungal medications (e.g., Nystatin, Ketoconazal, Diflucan). It is also recommended that the person be placed on a special diet, low in sugar and other foods on which yeasts thrive. Interestingly, if the candida albicans is causing health and behavior problems, a person will often become quite ill for a few days after receiving a treatment to kill the excess yeast. The yeast is destroyed and the debris is circulated through the body until it is excreted. Thus, a person who displays negative behaviors soon after receiving treatment for candida albicans (the Herxheimer reaction) is likely to have a good prognosis.

Please note: treatment for candida albicans infrequently results in a cure for autism. However, if the person is suffering from this problem, his/her health and behavior should improve following the therapy.