Facteurs de risque environnementaux de l'autisme: examen fondé sur des données probantes des revues systématiques et des méta-analyses

Aperçu: G.M. 

Les données actuelles suggèrent que plusieurs facteurs environnementaux, dont la vaccination, le tabagisme maternel, l'exposition au thimérosal et les techniques de reproduction assistée les plus probables, ne sont pas liés au risque de TSA. Au contraire, l'âge avancé des parents est associé à un risque accru de TSA. Les complications liées à la naissance associées au traumatisme ou à l'ischémie et à l'hypoxie ont également montré des liens forts avec les TSA, alors que d'autres facteurs liés à la grossesse tels que l'obésité maternelle, le diabète maternel et la césarienne ont montré une association moins forte (mais significative) .  

Les revues sur les éléments nutritionnels n'ont pas été concluantes sur les effets néfastes de la carence en acide folique et oméga 3, mais la vitamine D semble être déficiente chez les patients avec un diagnostic de TSA. Les études sur les éléments toxiques ont été largement limitées par leur conception, mais il y a suffisamment de preuves pour l'association entre certains métaux lourds (le mercure inorganique le plus important et le plomb) et le TSA pour mériter une enquête plus approfondie.

Mol Autism. 2017 Mar 17;8:13. doi: 10.1186/s13229-017-0121-4. eCollection 2017.

Environmental risk factors for autism: an evidence-based review of systematic reviews and meta-analyses

Modabbernia A¹, Velthorst E², Reichenberg A³.

Author information

1

0000 0001 0670 2351grid.59734.3cDepartment of Psychiatry and Seaver Autism Center, Icahn School of Medicine at Mount Sinai, New York, USA.

2

0000 0001 0670 2351grid.59734.3cDepartment of Psychiatry and Seaver Autism Center, Icahn School of Medicine at Mount Sinai, New York, USA ; 0000 0001 0670 2351grid.59734.3cDepartment of Preventive Medicine, Icahn School of Medicine at Mount Sinai, New York, USA.

3

0000 0001 0670 2351grid.59734.3cDepartment of Psychiatry and Seaver Autism Center, Icahn School of Medicine at Mount Sinai, New York, USA ; 0000 0001 0670 2351grid.59734.3cDepartment of Preventive Medicine, Icahn School of Medicine at Mount Sinai, New York, USA ; 0000 0001 0670 2351grid.59734.3cFriedman Brain Institute, Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, USA ; 0000 0001 0670 2351grid.59734.3cSeaver Autism Center, Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, USA.

Abstract

BACKGROUND:

According to recent evidence, up to 40-50% of variance in autism spectrum disorder (ASD) liability might be determined by environmental factors. In the present paper, we conducted a review of systematic reviews and meta-analyses of environmental risk factors for ASD. We assessed each review for quality of evidence and provided a brief overview of putative mechanisms of environmental risk factors for ASD.

FINDINGS:

Current evidence suggests that several environmental factors including vaccination, maternal smoking, thimerosal exposure, and most likely assisted reproductive technologies are unrelated to risk of ASD. On the contrary, advanced parental age is associated with higher risk of ASD. Birth complications that are associated with trauma or ischemia and hypoxia have also shown strong links to ASD, whereas other pregnancy-related factors such as maternal obesity, maternal diabetes, and caesarian section have shown a less strong (but significant) association with risk of ASD. The reviews on nutritional elements have been inconclusive about the detrimental effects of deficiency in folic acid and omega 3, but vitamin D seems to be deficient in patients with ASD. The studies on toxic elements have been largely limited by their design, but there is enough evidence for the association between some heavy metals (most important inorganic mercury and lead) and ASD that warrants further investigation. Mechanisms of the association between environmental factors and ASD are debated but might include non-causative association (including confounding), gene-related effect, oxidative stress, inflammation, hypoxia/ischemia, endocrine disruption, neurotransmitter alterations, and interference with signaling pathways.

CONCLUSIONS:

Compared to genetic studies of ASD, studies of environmental risk factors are in their infancy and have significant methodological limitations. Future studies of ASD risk factors would benefit from a developmental psychopathology approach, prospective design, precise exposure measurement, reliable timing of exposure in relation to critical developmental periods and should take into account the dynamic interplay between gene and environment by using genetically informed designs.

PMID: 28331572

PMCID: PMC5356236

DOI: 10.1186/s13229-017-0121-4