New study shows that autism not linked to vaccine

After a decade of controversy that has seen surges in measles outbreaks because of many parents' mistrust of the vaccine, a new US-led study concluded there is no link between the MMR vaccine and the onset of autism or gastrointestinal symptoms in children who develop both. The new study replicated the 1998 UK study that originally suggested there was a link between MMR and autism because it found measles virus in the bowels of a group of autistic children with gastrointestinal disorders who had been vaccinated.

The study, led by Ian Lipkin of the Mailman School of Public Health at Columbia University, New York, was published in PloS Medicine, the open-access journal.

Lipkin and colleagues carried out a case-control study to find out if children with gastrointestinal disturbances and autism were more likely to have measles virus RNA and/or inflammation in their bowel tissue than children who had gastrointestinal disturbances without autism. They also investigated whether the onset of autism and/or any gastrointestinal disturbance was linked to the timing of receiving MMR.

They took bowel tissue samples (ileal and cecal tissue) from 38 US children who were already undergoing ileocolonoscopy for clinical reasons because they had gastrointestinal disturbances. 25 of the children also had autism, while the other 13 did not (these were age-matched controls).

The tissue samples were tested for presence of measles virus in three separate laboratories that did not know the reason for the test, including one that was involved in the original 1998 study that reported a link between measles virus and autism.

In their analysis, Lipkin and colleagues focused on three points: the order of onset of autism, the onset of gastrointestinal episodes, and the timing of the MMR vaccine. They reported finding "no differences between case and control groups in the presence of MV [measles virus] RNA in ileum and cecum", and the results were the same across all three laboratories.

"GI symptom and autism onset were unrelated to MMR timing," wrote the authors, who also found that 88 per cent of the children with autism had behavioral regression. They concluded that:

"This study provides strong evidence against association of autism with persistent measles virus RNA in the gastrointestinal tract or MMR exposure. Autism with gastrointestinal disturbances is associated with elevated rates of regression in language or other skills and may represent an endophenotype distinct from other ASD."

People with autism spectrum disorders (ASDs) have significant difficulty interacting socially and communicating with others. They also learn, pay attention and react to situations differently to people who do not have ASD, with ability ranging from gifted to severely challenged, according to information from the US Centers for Disease Control and Prevention, whose scientists also took part in the study.

See the full article here http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0003140