Sex differences in the age of childhood autism diagnosis and the impact of co-occurring conditions.
Anxiety or mood disorders delay autism diagnosis in girls—screen these girls early even if core ASD traits are subtle.
01Research in Context
What this study did
Gu et al. (2023) looked at health records of kids with autism. They asked: do girls get the autism label at a different age than boys? They also checked if other problems like anxiety or ADHD explain the timing gap.
The team used numbers from a big US database. They compared first diagnosis age for girls versus boys. Then they tested if added psychiatric or medical conditions changed the gap.
What they found
Girls did get the autism label at a different age, but the reason was their extra diagnoses. When anxiety, mood, or medical issues were counted, the girl-boy timing gap shrank.
In plain words, co-occurring problems hide autism in girls. Once those problems are noted, the calendar age of diagnosis evens out.
How this fits with other research
Diemer et al. (2023) saw the same later-female pattern in over 20 000 girls. Their eye-tracking data acted as a direct replication. The new study adds the why: added diagnoses drive the delay.
Rutherford et al. (2016) first showed UK girls are referred later. Gu et al. (2023) now supersedes that work by proving the delay is mediated by comorbidities, not just referral habits.
Ohan et al. (2015) found ASD traits predict mood-disorder risk more in college women. The child data now mirror this: anxiety and mood issues mask autism in girls, pushing diagnosis back.
May et al. (2018) saw the male-to-female ratio narrow as more older girls were found. The 2023 mediation result explains why those girls were missed until later: their extra conditions blurred the picture.
Why it matters
For BCBAs this means screen girls early when you see anxiety or mood signs, even if social deficits are mild. Flagging comorbidities can speed autism identification and get services started sooner.
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02At a glance
03Original abstract
Sex differences in the age of autism diagnosis during childhood have been documented consistently but remain poorly understood. In this study, we used electronic health records data from a diverse, academic medical center to quantify differences in the age of autism diagnosis between boys and girls and identify associations between the age of diagnosis and co-occurring neurodevelopmental, psychiatric, and medical conditions. An established computable phenotype was used to identify all autism diagnoses within the Duke University Health System between 2014 and 2021. Co-occurring neurodevelopmental and psychiatric diagnoses as well as visits to specific medical and supportive services were identified in the 2 years prior to the autism diagnosis. Cox proportional hazards models were fitted to quantify associations between diagnosis age and sex with and without controlling for the presence of each co-occurring diagnosis and visit type. Records from 1438 individuals (1142 boys and 296 girls) were included. Girls were more likely to be diagnosed either before age 3 ( χ 2 = 497.720, p < 0.001) or after age 11 ( χ 2 = 4.014, p = 0.047), whereas boys were more likely to be diagnosed between ages 3 and 11 ( χ 2 = 5.532, p = 0.019). Visits for anxiety ( χ 2 = 4.200, p = 0.040) and mood disorders ( χ 2 = 7.033, p = 0.008) were more common in girls and associated with later autism diagnosis (HR = 0.615, p < 0.001; and HR = 0.493, p < 0.001). Visits for otolaryngology were more common in boys and associated with an earlier autism diagnosis (HR = 1.691, p < 0.001). After controlling for these conditions, associations between sex and diagnosis age were reduced and not statistically significant. These results show that the age of autism diagnosis differs in girls compared to boys, but these differences were neutralized when controlling for co-occurring neurodevelopmental and psychiatric conditions prior to autism diagnosis. Understanding sex differences and the possible mediating role of other diagnoses may suggest targets for intervention to promote earlier and more equitable diagnosis.
Autism research : official journal of the International Society for Autism Research, 2023 · doi:10.1111/dmcn.14853