* Différences sexuelles dans la connectivité des lobes frontaux chez les adultes avec des conditions du spectre de l'autisme

Aperçu: G.M.

Les conditions du spectre de l'autisme (ASC) sont plus répandues chez les hommes que chez les femmes. La base biologique de cette différence reste incertaine.

Les hommes avec ASC avaient des scores plus élevés de sévérité des symptômes actuels que les femmes et avaient des valeurs d'anisotropie fractionnée (FA significativement plus faibles pour tous les patients sauf un par rapport aux témoins. Aucune différence n'a été observée entre les femmes  avec ou sans ASC. Les effets significatifs du sexe par diagnostic se limitaient aux parcelles frontales. En prenant en compte les scores actuels de sévérité des symptômes de l'ASC, cela n'a pas modifié les résultats.

Ces découvertes d'anomalies de connectivité frontale chez les hommes avec ASC, mais pas chez les femmes avec ASC, ont le potentiel de nous informer sur certaines des différences de sexe rapportées dans le phénotype comportemental de l'ASC. 

Transl Psychiatry. 2017 Apr 11;7(4):e1090. doi: 10.1038/tp.2017.9.

Sex differences in frontal lobe connectivity in adults with autism spectrum conditions

Zeestraten EA¹, Gudbrandsen MC¹, Daly E¹, de Schotten MT¹, Catani M¹, Dell'Acqua F¹, Lai MC^2,3,4, Ruigrok AN², Lombardo MV^2,5, Chakrabarti B^2,6, Baron-Cohen S^2,7, Ecker C¹; MRC AIMS Consortium, Murphy DG^1,8, Craig MC^1,9.

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Abstract

Autism spectrum conditions (ASC) are more prevalent in males than females. The biological basis of this difference remains unclear. It has been postulated that one of the primary causes of ASC is a partial disconnection of the frontal lobe from higher-order association areas during development (that is, a frontal 'disconnection syndrome'). Therefore, in the current study we investigated whether frontal connectivity differs between males and females with ASC. We recruited 98 adults with a confirmed high-functioning ASC diagnosis (61 males: aged 18-41 years; 37 females: aged 18-37 years) and 115 neurotypical controls (61 males: aged 18-45 years; 54 females: aged 18-52 years). Current ASC symptoms were evaluated using the Autism Diagnostic Observation Schedule (ADOS). Diffusion tensor imaging was performed and fractional anisotropy (FA) maps were created. Mean FA values were determined for five frontal fiber bundles and two non-frontal fiber tracts. Between-group differences in mean tract FA, as well as sex-by-diagnosis interactions were assessed. Additional analyses including ADOS scores informed us on the influence of current ASC symptom severity on frontal connectivity. We found that males with ASC had higher scores of current symptom severity than females, and had significantly lower mean FA values for all but one tract compared to controls. No differences were found between females with or without ASC. Significant sex-by-diagnosis effects were limited to the frontal tracts. Taking current ASC symptom severity scores into account did not alter the findings, although the observed power for these analyses varied. We suggest these findings of frontal connectivity abnormalities in males with ASC, but not in females with ASC, have the potential to inform us on some of the sex differences reported in the behavioral phenotype of ASC.

PMID 28398337

DOI: 10.1038/tp.2017.9