Causes of Autism Spectrum Disorders

During the 1950s and 1960s Bruno Bettelheim perpetuated the notion that autism could be attributed to the psychopathology of parents. Bettelheim’s (1967) theory of psychogenesis claimed that autism was an outcome of disinterested, cold parents who were unable to develop an emotional bond with their children. Sadly, mothers of children with autism were called “refrigerator mothers” and led to believe they were the cause of their children’s disability.

For parents, the idea that they are to blame creates a great deal of guilt on top of the grief already experienced when they find their toddler exhibiting the disturbing behaviors characteristic of autism. No causal link between parental personality and autism has ever been discovered; and in 1977, the National Society for Autistic Children (today the Autism Society of America) stated, “No known factors in the psychological environment of a child have been shown to cause autism.” Nevertheless, many parents “are still trying to overcome the guilt and the professional bullying associated with that initial blame” (Scheuermann & Weber, 2002, p. 2).

Although the precise neurobiological mechanisms that cause autism have not yet been discovered, “it is clear that autism reflects the operation of factors in the developing brain (National Research Council, 2001, p. 11). (The cause of Rett’s syndrome has been identified as an abnormality in the MECP2 gene on the X chromosome.) Recent research shows a clear biological origin for autism in the form of abnormal brain development, structure, and/or neurochemistry (Akshoomoff, 2000; Mauk, Reber, & Batshaw, 1997). Numerous genetic links to autism have been established, but we still do not completely understand their causal relationships (Autism Research Institute, 1998; Mueller & Courchesne, 2000). Autism might best be viewed as a behavioral syndrome that may be produced by multiple biological causes (Berney, 2000; Mueller & Courchesne, 2000). Experts now suspect that genes may make a child more susceptible to autism but that environmental factors may trigger it. What these environmental factors are is still unknown.

It is not known what causes autism, although research continues to get us closer to answering that question. There is clearly a genetic component to the disorder: having one child with autism greatly increases the chances of having another child with autism. However, genetics is not the only factor involved because if one identical twin has autism, the other twin may not. Since identical twins share the same genes, some other factor must be contributing to the presence of autism. The current theory among autism genetics researchers supports the idea of complex inheritance. This means that multiple genetic factors are likely to be involved, which in combination may predispose an individual to developing autism. In addition to having the right combination of autism-related genes, exposure to certain environmental factors might lead to the development of autism in some individuals (National Alliance for Autism Research, 2002).

Although questions have been raised about whether vaccinations (specifically, the measles-mumps-rubella [MMR] vaccine and vaccines containing thimerosal and used for protection against diphtheria, tetanus, pertussis, and hepatitis B) could be a factor involved in autism, no evidence of this relationship has been found (Immunization Safety Review Committee, 2004).