Reference: Van Wijngaarden-Cremers, P., van Eeten, E., Groen, W., Van Deurzen, P., Oosterling, I. and Van der Gaag, R. (2013). Gender and Age Differences in the Core Triad of Impairments in Autism Spectrum Disorders: A Systematic Review and Meta-analysis. Journal of Autism and Developmental Disorders, 44(3), pp.627-635.
A meta-analysis of studies into the effect of gender on autism. Current findings on whether there is a gender difference are inconsistent. To investigate further, the meta-analysis also looked at the effect of age in conjunction with gender.
The meta-analysis looked at 22 studies which reported on gender differences in social and/or communication deficits, and differences in repetitive and stereotyped behaviour. Due to the variation in the studies the following data was used:
- For social deficits, there were 4,783 test scores from males and 1,277 test score from females
- For communication, there were 2,781 scores from males and 992 for females
- For repetitive and stereotyped behaviour there were 2,093 scores from males and 781 scores from females.
- The meta-analysis found very few differences in symptom severity between males and female.
- Symptom severity in communication and social behaviour was similar between genders, girls showed less restricted interests, behaviours and stereotypes than boys. This difference was not significant below the age of 6, only after.
- There are three hypotheses for this difference:
- Females present with a different autism phenotype to males
- Female ASD patients with Intellectual Disability may be over-represented in the studies used, and stereotyped and repetitive behaviours are not ASD-specific – they also present in ID.
- Females with less severe social and communication deficits were misdiagnosed with other conditions and therefore not included in these studies.
May have been false-positive ASDs among patients with restricted interests and behaviours and stereotypes as there was an over identification of these symptoms as autistic traits when they are also common in some regularly developing children, and those with Intellectual Disability or who experienced deprivation.
Females with normal to high intelligence may have been missed from the meta-analysis.
Intellectual Disability as a confounder could not be controlled for with the data available.
What to take from this for practical use?
Girls and women may present differently in terms of social and communication difficulties.
Girls with normal or above intelligence may exhibit less repetitive behaviours, it may be more difficult to identify ASD traits.
Repetitive behaviours and interests alone are not ASD, they are equally common in other conditions and in some typically developing children.
Even if there are some presentation differences, women and girls with ASD do still have (and still require for diagnosis) social and communication difficulties, and repetitive interests, behaviours or thoughts.