Vaccines and the changing epidemiology of autism.

BACKGROUND

The epidemiology of autism has been rather confusing, with very variable published prevalence figures and no clear incidence data. The cause of autism is unclear; vaccines have been incriminated.

METHODS

Literature review and interpretation.

RESULTS

The recorded prevalence of autism has increased considerably in recent years. This reflects greater recognition, with changes in diagnostic practice associated with more trained diagnosticians; broadening of diagnostic criteria to include a spectrum of disorder; a greater willingness by parents and educationalists to accept the label (in part because of entitlement to services); and better recording systems, among other factors. The cause(s) of autism remains unclear. There is a strong genetic component which, along with prenatally determined neuro-anatomical/biochemical changes, makes any post-natal 'cause' unlikely.

CONCLUSIONS

There has (probably) been no real increase in the incidence of autism. There is no scientific evidence that the measles, mumps and rubella (MMR) vaccine or the mercury preservative used in some vaccines plays any part in the aetiology or triggering of autism, even in a subgroup of children with the condition.