Environmental risks in the development of autism and autism spectrum disorders

Jul 8 2004

Funding for a new study to find out more about the role of environmental risks in the development of autism and autism spectrum disorders (ASD), has been announced by the Medical Research Council (MRC).

It is one of four new awards for research projects using a variety of approaches to study autism.

The environmental research, led by Professor Jean Golding at the University of Bristol, will investigate the association of ASD with immunisations, problems with delivery, maternal and infant infections, fetal exposure to toxins, and maternal diet. Whether other conditions, such as coeliac disease or digestive problems, play a role in the development of ASD will also be considered.

The £400,000 study will be one of the largest investigations of environmental risk factors in ASD and will analyse lifestyle and genetic influences by studying data from the 14,000 children already taking part in the ‘Children of the 90s’ study. The ‘Children of the 90s study’ was set up to understand the ways in which the physical and social environment interact with genetic inheritance to affect children’s health, behaviour and development.

Professor Golding said: “Because of the number of children we’ll be looking at, and the quality and type of data available, our study should help find the answers to a number of currently unanswered questions about the environmental risks for developing autism spectrum disorders.”

The award to Children of the 90s will allow researchers to go back through data on 14,000 children, looking for signs of behaviour associated with autism.

Doctors’ records already exist on the relatively small number of children who have been diagnosed with autism or autistic spectrum disorders. By going back through data collected on all the children, the researchers will also be looking for a number of traits including:delay in learning to speak

• poor communication skills
• repetitive obsessional behaviour
• limited empathy

Then – scientists will examine the history of the pregnancy, the birth, and early childhood in those cases, trying to identify any common factors.

Professor Golding said: “One theory suggests that the causes of autistic behaviours arise very early in pregnancy – even in the first few weeks.

“While it is true that this disorder does sometimes run in families – it isn’t purely genetic. One possibility is that something happens in the womb, which interacts with a gene – and the result is a child with an autistic spectrum disorder.

“For instance - Is there evidence that the mothers of children with particular autistic traits were exposed to infections more often in pregnancy than mothers of unaffected children?

“A number of possible causes have been suggested – and we shall be testing various hypotheses concerning the cause and origin of each trait, whether it is genetic or environmental.”

The specific areas under investigation include:

• infection during pregnancy and early childhood
• diet during pregnancy and in infancy
• factors which may harm the baby in the womb – such as nicotine or alcohol
• complications at birth
• immunisation and reaction to vaccines
• other illness including bowel disorders, allergies, developmental disorders
• genetic influences
• Although it was first identified in 1943, autism is still a relatively unstudied disability. Autistic spectrum disorders are estimated to affect approximately one in 100 people (more than 500,000 people in the UK).

Autistic disorders are developmental disabilities that affect the way a person communicates and relates to people around them. Affected children and adults have difficulties with everyday social interaction. Their ability to develop friendships is generally limited as is their capacity to understand other people's emotional feelings.

People with autistic disorders can often have accompanying learning disabilities but everyone with the condition shares a difficulty in making sense of the world.

Overall the awards total £1.6 million for autism research. They have been funded out of the £2.75 million allocated by the Department of Health and the Scottish Executive to take forward the recommendations of the 2001 MRC Review on Autism. The remaining funds will be used to support more grants in the near future.