Autism is a neurodevelopmental condition. The causes are not yet understood but genetics appear to have a pivotal role with multiple genes being associated with autism.1
Research has identified strong associations with genetic mutations, for example fragile X syndrome in boys. Around 10 per cent of autistic children have genetic changes (deletions or duplications called copy number variations of CNVs) capable of causing disease. The level may rise to 30 per cent where epilepsy or congenital abnormalities are involved. Tuberous sclerosis, a rare genetic condition causing benign lung tumours, is also associated with autism.7
Advanced parental age may increase the risk of autism in progeny, as may complications in the pregnancy or birth. Environmental factors may also have a role and some medications have been suggested.8,9,10
Paracetamol taken by pregnant women has been linked with a 19 per cent increase in borderline or clinical autism among their children. Valproic acid was associated with increased risk of autism when taken by pregnant women for epilepsy (but the same study found no evidence of increased risk specifically due to lamotrigine or carbamazepine).11,12
While there is an apparent link between taking selective serotonin re-uptake inhibitors (SSRIs) during pregnancy and autism in the offspring, researchers question whether this is a causative effect.13,14
There is no indication that vaccines, including the measles, mumps and rubella (MMR) vaccine, cause autism.1,15
Prenatal vitamins including folic acid (and started before conception) may reduce the risk of autism in children.8,16