Folic acid supplements linked to lower autism risk.
Maternal use of folic add supplements around the time of conception was associated with a lower risk of autistic disorder, the most severe form of autism spectrum disorders, in the children, according to a Norwegian study.
"This finding does not establish a causal relation between folic add use and autistic disorder, but provides a rationale for replicating the analyses in other study samples and further investigating genetic factors and other biologic mechanisms that may explain the inverse association," said Dr. Pal Suren of the Norwegian Institute of Public Health, Oslo, and his associates.
For this analysis, the researchers assessed data concerning 85,176 children in the Norwegian Mother and Child Cohort Study, a national registry of 109,020 children born between 1999 and 2009. At final follow-up, the subjects ranged in age from 3.3 years to 10.2 years (mean age, 6.4 years). A total of 270 of these children (0.32%) were diagnosed as having autism spectrum disorders: 0.13% had autistic disorder, 0.07% had Asperger's syndrome, and 0.12% had pervasive developmental disorder not otherwise specified (JAMA 2013;309:570-7).
Approximately 33% of the mothers took folic acid supplements during the interval from 4 weeks before conception to 8 weeks afterward. This period was chosen for the analysis because folic acid's effects on the developing central nervous system of the fetus are most prominent during this time. They found an inverse association between the mother's use of folic add supplements periconceptually and the risk that the child would develop autistic disorder. Of the children whose mothers took the supplements, 0.10% developed autistic disorder, compared with 0.21% in children whose mothers did not. The adjusted odds ratio of autistic disorder was 0.61 in children of folic add users. Further adjusting the data to account for comorbid maternal illness and concomitant medication use did not change this OR, Dr. Suren and his associates reported .
The inverse association for folic add use in the periconceptual period was not evident in mothers who took the supplements only later in pregnancy.
"Our findings indicate that the inverse association may be largely driven by the children with autistic disorder and severe language delay at 35 months, who were presumably the more severely affected children," the investigators added.
This study was funded in part by the Research Council of Norway. The investigators did not report having any financial conflicts of interest.