Evidence to support a connection between the MMR vaccine and incidents of autism is hard to come by. An epidemiological study in Japan found no connection. Tokio Uchiyama, Michiko Kurosawa and Yutaka Inaba, in a July 2006 study, found no evidence to support a causal relationship between the MMR and autism:
Abstract It has been suggested that the measles, mumps, and rubella vaccine (MMR) is a cause of regressive autism. As MMR was used in Japan only between 1989 and 1993, this time period affords a natural experiment to examine this hypothesis. Data on 904 patients with autism spectrum disorders (ASD) were analyzed. During the period of MMR usage no significant difference was found in the incidence of regression between MMR-vaccinated children and non-vaccinated children. Among the proportion and incidence of regression across the three MMR-program-related periods (before, during and after MMR usage), no significant difference was found between those who had received MMR and those who had not. Moreover, the incidence of regression did not change significantly across the three periods.