Knowledge of the causes of autism, despite the efforts of researchers, is not complete. Hypotheses centre around abnormal development or early damage to the central nervous system, caused by genetic and environmental conditions. At the same time, it is known that the onset of autism is not influenced by parental errors or neglect.

Genetic factors

A large contribution of genetic conditions to the development of autism is indicated by the results of population-based studies. They found a significant increase in the risk of autism in first-degree relatives (18-20% for siblings) and a high concordance rate for the development of the disorder in monozygotic twins (60-90%) compared to dizygotic twins (0-20%). It has also been estimated that heritability (the contribution of genetic factors to the risk of developing the disorder) in ASD is 0.4-0.9, one of the highest rates among all mental health disorders.

Furthermore, autism is more common in children with chromosomal defects. Examples include fragile X chromosome syndrome. It affects 3-10% of boys and 5% of girls with holistic developmental disorders.

Environmental factors

Environmental factors that may influence the occurrence of autism include.

  • prematurity
  • heavy metal poisoning;
  • parental age;
  • diabetes; hypothyroidism in the mother;
  • use of antiepileptic drugs by the mother during pregnancy;
  • prenatal stress;
  • infections.

Is there a link between autism and vaccination?

Available epidemiological data do not suggest a causal link between measles, mumps and rubella vaccination and autism spectrum disorder. A study from years ago, which suggested the existence of this relationship, was methodologically flawed. There is also no evidence that any other vaccination can increase the risk of autism.