With autism’s rise comes an increased understanding of its causes, as well as possibly how to help reduce our risks.

A spectrum disorder ranging from mild to severe, autism is characterized by language differences, repetitive behaviors, restricted interests, rigid thinking, and social interaction difficulties. It is caused by a combination of genetic and environmental factors, or epigenetics. Autism has a gene-based beginning (genetic predisposition) which, in combination with environmental factors, causes autism to emerge.
 
Autism tends to run in families. Identical twins have a high autism concordance rate—both twins often have the disorder, but not always. This means that environmental factors are also at play. What is inherited genetically is a vulnerability to autism. Environmental factors increase the probability of autism in children at risk, but do not cause it.
 
The best preventative measure is avoidance of environmental risk factors before and during a pregnancy, especially if there is a genetic risk (relatives with autism). Since there is no genetic test for this disorder, it is wise for all expectant mothers to be aware of the environmental risk factors.

At its core, autism is a neuro-developmental disability. The brains of children with autism show abnormalities that are likely to have occurred before birth. For a brief period there was concern that postnatal factors such as immunizations were to blame; however, no compelling evidence has demonstrated a link between immunizations and autism. In fact, avoiding immunizations is likely to compromise healthy development.


Increased risks & actions to take

No one can change their genetic make-up; however as we age, genes change or mutate. This may explain why autism risk increases when older parents (over age 30) conceive.
 
Environmental risk to a developing fetus is filtered through the mother, so maternal health during pregnancy is essential. Mothers must obtain quality prenatal care, eat a healthy diet, and take prenatal vitamins, which have been shown to be an important factor in reducing autism risks. Also, they must remain free of disease (especially rubella). Mothers should also speak with their doctors about prescription medications (including valproic acid for treatment of seizures, and depression medications). Maternal stress during pregnancy has also emerged as a risk factor for autism (probably mediated by stress hormones).
 
Between pregnancies, a woman’s body recovers and restocks nutrients such as folate and iron. This may be why autism rates are somewhat higher in closely spaced babies. This constitutes a source of stress on the mother’s body. Spacing babies two to three years apart may reduce autism risk, but more research is needed before this is conclusive. Elective Caesarian sections before a baby’s due date and preterm birth (nine or more weeks early) also compound autism risk.
One theory about the increasing autism rate is the escalation of various forms of pollution, food additives, plastics, and exposure to pesticides. Studies of phthalates, a group of chemicals found in plastics, are being done to see if there is a relation to autism risk.
 
The take-home message for parents is that autism results from a complex relationship of factors including genetic predisposition and exposure to environmental risk. None of the risk factors reviewed here causes autism. However, exposure to these risk factors may increase the risk of autism in genetically vulnerable babies. The degree of exposure and the number of combined risk factors has an impact as well.
 
Awareness of risk may guide the choices of women during pregnancy. Healthy nutrition including organic foods and prenatal vitamins, avoiding unhealthy amounts of stress, good prenatal care, consultation about prescription medications, reducing exposure to phthalates (avoid food cooked in plastic) and carrying a baby to term are reasonable precautions to take during pregnancy and may reduce autism risk.

By Pat Blackwell, Ph.D.