It has been reported that girls with an autism diagnosis have more severe impairments in social communication compared to boys.
A ratio of about four boys are diagnosed with autism for every one girl, although this ratio may reflect bias in the diagnostic process. The tools used to screen and diagnose the condition are based primarily on data from boys.
According to the study, girls are likely to receive an autism diagnosis only if they have significant social impairments – supporting the idea that diagnostic tools miss some girls with the condition.
“That’s certainly the concern” says Lead investigator Laura Carpenter, professor of paediatrics and psychiatry at the Medical University of South Carolina in Charleston. “Are we missing girls who are more mildly affected?”
“The study makes a contribution in terms of showing these large-scale population differences on autism spectrum markers,” says Rene Jamison, clinical associate professor at the University of Kansas Medical Center in Kansas City, who was not involved in the study. “This illustrates the need to consider sex-specific reference groups.”
Carpenter and her colleagues screened 1,731 boys and 1,789 girls between the ages of 8 and 10 for autism using the Social Communication Questionnaire (SCQ) completed by their parents.
From their SCQ scores, the researchers found about 5 percent of the girls and 9 percent of the boys where at risk of for autism. A random sample of 160 children who did not score in the ‘at risk’ range also completed the assessment.
About 25 percent of the boys went on to receive an autism diagnosis, compared with 7.4 percent of the girls.
Girls who received an autism diagnosis appeared to overlap with those who met the SCQ cut off, suggesting the screen is accurate for girls. However, the results hint that the diagnostic assessment is skewed to finding boys with the condition.
Testing the Test
“The interpretation I’m instinctively going for is that the actual diagnostic assessment is biased against the female autism phenotype,” says William Mandy, senior lecturer in clinical psychology at University College London, who was not involved in the study. The results were published 30 March in the Journal of Clinical Child and Adolescent Psychology.
Carpenter’s team plan to look at sex differences in autism features among younger children, using several screening and diagnostic tools due to some questioning on SCQ’s accuracy.
The SCQ appears to be problematic as a screen for boys as it shows that about 10 percent of boys fall below the at-risk cut off have autism. Suggesting that clinicians should look more closely at boys who don’t seem to meet SCQ Criteria.
In comparison, “items measuring children’s social and spontaneous behaviours at ages 4 and 5, when autism features become apparent, are most predictive of an autism diagnosis. These questions are also particularly good at identifying girls with the condition. Questions about restricted and repetitive behaviours, however, are not good predictors of the condition in either girls or boys.”
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HCB Education Law Advice, Specialist Solicitors