aetiological and risk factors

Last edited 02/2018 and last reviewed 07/2022

  • genetic component - risk in the siblings of autistic children is 3 or 4 times higher than in the general population; more common in boys than girls (approximately 4:1).
  • organic cause is suggested by the development of seizures in some 40% of these children when they reach adolescence.

Kanner in his original description of the condition in 1943 suggested that the behaviour of the autistic child was a response to abnormalities in the parents, characterised as cold, detached and 'obsessive'. These ideas have not been substantiated by research.

Autism is associated with:

  • the fragile X syndrome
  • Rett's syndrome

NICE note factors associated with an increased prevalence of autism (1)

  • a sibling with autism

  • birth defects associated with central nervous system malformation and/or dysfunction, including cerebral palsy

  • gestational age less than 35 weeks

  • parental schizophrenia-like psychosis or affective disorder

  • maternal use of sodium valproate in pregnancy

  • a learning (intellectual) disability

  • attention deficit hyperactivity disorder

  • neonatal encephalopathy or epileptic encephalopathy, including infantile spasms

  • chromosomal disorders such as Down's syndrome

  • genetic disorders such as fragile X

  • muscular dystrophy

  • neurofibromatosis

  • tuberous sclerosis