A recent study showed an increased risk of autism with intellectual disability among the children of certain groups of immigrants. The register study by the Swedish medical University Karolinska Institutet included all children in Stockholm County from 2001 to 2007. The results raise the question of heredity in autism.
“This is an intriguing discovery, in which we can see strong links between a certain kind of autism and the time of the mother’s immigration to Sweden,” says principal investigator Cecilia Magnusson, Associate Professor of epidemiology at Karolinska Institutet. “The study is important, as it shows that autism isn’t governed only by genetic causes but by environmental factors too.”
The study shows that children of immigrant parents particularly mothers who migrated just before or during pregnancy are disproportionately more likely to develop autism with intellectual disability. This link seems to be related to the timing of the migration rather than complications in childbirth.
There is also supporting evidence of autism anomalies in immigrant communities in the United States. In Minneapolis, Somalis account for 6 percent of the city’s public school population, but make up 17 percent of early childhood special education students who have been labeled autistic, according to data aggregated by the Minneapolis Public Schools.
Public health experts say it is hard to tell whether the apparent surge of cases is real or just a statistical fluke.
While there are still many elements of these results to be investigated, if autism rates have significantly increased in some Somali immigrant communities, above what is seen in Somalia or in non-Somali in the same communities, then we can conclude that something is going on and a potential trigger should be sought.
Various other studies spanning over the last thirty years have shown similar results but a possible explanation is yet to be identified and explored.
“At this juncture we can but speculate about the causes, but our assumption is that environmental factors impacting on the developing fetus, such as stress, new dietary habits or infections, could lead to the development of autism with intellectual disability,” says Dr Magnusson.
Of all the children examined in Stockholm, some 5,000 had received a diagnosis according to the different registers. In all, 589,114 children were included in the study.