Parental migration and Asperger’s syndrome.
Parental immigration has been suggested as a possible risk factor for autism spectrum disorders (ASD), but findings have been inconsistent.Very few studies have focused specifically on Asperger’s syndrome. The aim of this study was to examine the association between maternal and paternal immigration and the diagnosis of Asperger’s syndrome in offspring.The study was a nested case-control study based on a national birth cohort in Finland. Children born in 1987-2005 and diagnosed with Asperger’s syndrome by the year 2007 were identified from the Finnish Hospital Discharge Register (N = 1,783). Four matched controls for each case were selected from the Finnish Medical Birth Register (N = 7,106). Information on maternal and paternal country of birth and mother tongue was collected from the Finnish Central Population Register.
The study showed that children whose parents are both immigrants have a significantly lower likelihood of being diagnosed with Asperger’s syndrome than those with two Finnish parents [adjusted odds ratio (aOR) 0.2, 95 % confidence interval (CI) 0.1-0.4].
No significant associations were found between having only one immigrant parent and the diagnosis of Asperger’s syndrome.A regional analysis showed a significantly decreased likelihood of the diagnosis of Asperger’s syndrome in children whose mother (aOR 0.1, 95 % CI 0.01-0.5) or father (aOR 0.2, 95 % CI 0.05-0.5) was born in Sub-Saharan Africa.
The findings may help in identifying risk factors for different ASD subtypes. On the other hand, they might reflect service use of immigrant families in Finland.
The risk of childhood autism among second-generation migrants in Finland: a case-control study.
Studying second-generation immigrants can help in identifying genetic or environmental risk factors for childhood autism. Most previous studies have focused on maternal region of birth and showed inconsistent results. No previous study has been conducted in Finland.
The study was a nested case-control study based on a national birth cohort. Children born in 1987-2005 and diagnosed with childhood autism by the year 2007 were identified from the Finnish Hospital Discharge Register. Controls were selected from the Finnish Medical Birth Register. Information on maternal and paternal country of birth and mother tongue was collected from the Finnish Central Population Register. There were 1132 cases and 4515 matched controls. The statistical test used was conditional logistic regression analysis.
Compared with children with two Finnish parents, the risk of childhood autism was increased for those whose parents are both immigrants (adjusted odds ratio [aOR] 1.8, 95% confidence interval [CI] 1.2-2.7) and for those with only an immigrant mother (aOR 1.8, 95% CI 1.2-2.7), but not for those with only an immigrant father.
The risk was increased for those with a mother born in the former Soviet Union or Yugoslavia and for those with a mother or a father born in Asia.
Specific parental countries of birth associated with an increased risk were the former Soviet Union, the former Yugoslavia and Vietnam.
In Finland, children who are born to immigrant mothers with or without an immigrant partner, have an increased risk of childhood autism. The risk varies with immigrant parents’ region of birth. The findings may help in identifying possible risk factors, which can be examined in future studies.