About Even though two individuals may share the diagnosis of autism, the symptoms they exhibit may vary greatly. Autism, or Autism Spectrum Disorder (ASD), diagnoses are based on observation of symptoms and not on medical tests, making isolating a cause of autism difficult. Ongoing research is discovering, however, some connections that may uncover risk factors associated with the development of autism.
Autism is usually diagnosed before age 3 and sometimes as early as 18 months. Like many other childhood conditions, autism is not per se preventable. There are risk factors that researchers have identified as potential associations, such as a breech presentation at birth, a low Apgar score (the score used to evaluate the condition of a newborn 5 minutes after birth), birth before week 35 of pregnancy, a parental history of schizophrenia-like psychosis, and a parental history of affective disorders including depression and bipolar disorder.
Studies conducted by the Centers for Disease Control and Prevention have indicated that children who are born early or underweight have a risk of developing autism that is nearly double the rate of those born full-term at a healthy weight.
Research has also indicated that some genes may be responsible for autism. To date, no single gene has been identified as a cause of autism, but some families have a pattern of autism. It appears that some children are born susceptible to autism, and research is being conducted on whether the development of some genes interferes with brain development that results in autism.
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.
Studies regarding the genetic link to autism have found that, among identical twins, if one twin has autism, then the other is affected about 75% of the time. The figure for non-identical twins is about 3%. In families with one child who an ASD, then there is a 2 to 8 % chance of a second child also having an ASD.
Certain medical conditions such as tuberous sclerosis, congenital rubella syndrome, Fragile X syndrome, and untreated phenylketonuria are associated with an increased risk for autism. Exposure to some harmful drugs during pregnancy, such as thalidomide, is also associated with an increased risk.
While parents are usually the first to notice symptoms of autism in their child, parenting is not a risk factor in the development of autism. Knowing the warning signs and the milestones for normal development, however, can assist in obtaining evaluation and diagnosis and therefore early intervention and treatment in an affected child.
While many theories exist that link routine childhood vaccinations with an increased risk of autism, no scientific proof exist that there is a causal connection between the two.
No one single cause of autism has been identified. However, with ongoing research into risk factors, perhaps preventative measures against the development of this complex disorder can be implemented. Research may also lead to more effective treatments and interventions as well.
References & Resources:
Read the US Centers for Disease Control and Prevention’s autism risk factors page here.