While there are no definitive causes of autism, research has found some common risk factors in children who have been diagnosed with this complex disorder. According to the US Centers for Disease Control and Prevention, about 1 in 150 children will have autism, and that number is growing (Whether this increase represents a true increase in prevalence or whether it reflects an increased awareness and better diagnoses is a topic of debate). What researchers do know is that autism is more prevalent in boys than in girls, although the cause of that has not been determined.
Autism is not a contagious disorder, nor is it caused by parenting techniques, but it does seem to run in families. For instance, identical twins are very likely to share an autism diagnosis, and fraternal twins are more likely than other relatives to share a diagnosis.
Some common risk factors for autism are low birth weight and premature birth; advanced parental age; and spontaneous genetic mutations whose cause is unknown. Some researchers believe that, in children with a genetic inclination toward autism, an environmental exposure may trigger symptoms. Recent studies by researchers at John Hopkins University link autism with a mother’s autoimmune disorders such as celiac disease and rheumatoid arthritis. The Johns Hopkins study concluded that, if one of these disorders is present in the mother, the risk of autism in her child is increased threefold.
Research has not found a causal connection between exposure to mercury used in routine childhood vaccinations and autism, nor is there any clear research connecting children with seizure disorders, bipolar disorder, sensory integration dysfunction, digestive issues, or food allergies and autism, although some of these problems may co-exist in children with autism.
No two children with autism will share identical symptoms; autism is a spectrum disorder, meaning that symptoms vary widely among individuals who are affected by it. Because of the complexity of the disorder, and the fact that it is diagnosed based on observation of behavior and not on a medical test, isolating risk factors and causes is tricky. Research into causality continues, and research into new theories is growing. Until more definitive answers regarding causality can be found, a focus on early diagnosis and appropriate treatment and intervention is imperative in order to effectively treat children with autism diagnoses.
Additional Resources:
Read the US Centers for Disease Control and Prevention’s autism risk factors page here.
References:
http://autism.about.com/od/autismbasicsfaqs/f/riskofautism.htm