The number of children diagnosed with autism is rising. What is being done to find out the causes of autism? Is the Measles, Mumps and Rubella (MMR) vaccine responsible for the increased prevalence?

Sheila Hollins (UK)

The Medical Research Council's (2002) wide-ranging review of autism research outlines the current state of knowledge on the prevalence and incidence of autism. There is general agreement that the prevalence of autism is around 6 in 1,000 children under eight years of age, of whom about two thirds will also have intellectual disabilities. The review notes that the apparent increase in the prevalence of autism is likely to have resulted from better diagnosis and greater consensus regarding the defining characteristics of autism, as well as increased awareness about it. However, it points out that these factors may not account for the increase on their own.

The review confirms that many factors are associated with a diagnosis of autism. The strongest evidence to date identifies a major genetic component.

Several genes may operate together to create susceptibility to autism. It is plausible that behaviours associated with autism might be derived from a number of different genetic combinations. Further, such environmental factors as exposure to drugs, infections or heavy metals before or after birth might interact with a genetic susceptibility. Such potential links merit rigorous examination.

The report asserts that there is no evidence to support a causal link between the MMR vaccine and autism. The suggested link between the MMR vaccine, inflammatory bowel disease and autism and the issue of separate (single) vaccines has also been considered by the Government's independent expert committees i.e. the Joint Committee on Vaccines and Immunisation and the Committee on the Safety of Medicines. Their view is that, on the scientific evidence available, there is no causal link between MMR, bowel disease and autism.

The MMR vaccine has been used extensively around the world for nearly 30 years. Over 500 million doses have been given in over 90 countries.

The UK has never recommended three separate injections, and no other country is known to recommend three single vaccines rather than the MMR vaccine. Separate vaccines leave children unnecessarily at risk of infection from measles, mumps or rubella whilst waiting for the remaining vaccinations.

The recommendations regarding MMR are supported by the World Health Organisation, British Medical Association, Royal College of General Practitioners, Royal College of Paediatrics and Child Health, Royal College of Nursing and the Community Practitioners and Health Visitors Association.

Medical Research Council (2002) Review of Autism Research: Epidemiology and Causes. London, MRC.

This article was first published on the site in 2002.