The role of intellectual disability with autism spectrum disorder and the documented cooccurring conditions: A population-based study.
Semra Etyemez, Amy Esler, Aniket Kini and 4 others
PMID 36245337WHAT IT FOUND
Children with autism and intellectual disability were more likely to have documented neurological conditions and general developmental delays, but less likely to have recorded diagnoses for ADHD, anxiety, or learning disorders compared to those without intellectual disability.
Key findings
01Children with autism and intellectual disability had higher odds of documented neurological diagnoses like epilepsy and cerebral palsy compared to those without intellectual disability.
02Children with autism and intellectual disability had lower odds of documented non-autism developmental disorders like ADHD and learning disorders compared to those without intellectual disability.
03Children with autism and intellectual disability had lower odds of documented psychiatric disorders like anxiety and mood disorders compared to those without intellectual disability.
STILL TO COME
How it was doneWhat they foundWhat it means for PTsWhat it means for OTsWhat it means for SLPs
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What it does not show
The study is cross-sectional, so it cannot determine if the co-occurring conditions caused the ID or vice versa, or if they developed in a specific sequence. Co-occurring conditions were identified from existing records, not through direct clinical assessment, meaning diagnoses relied on how providers documented them, which may vary by site and clinician. 42.8% of children had missing IQ data and were excluded from the ID status grouping, potentially biasing the sample. The timing of diagnoses was not tracked; some conditions recorded between birth and age 8 may have been transient, resolved, or later attributed to ASD rather than being distinct co-occurring conditions. There was significant variability in findings across different study sites, likely due to differences in local diagnostic practices and record access.
Declared interests
The ADDM Network is funded by the Centers for Disease Control and Prevention (CDC).
The easy way to misread this
Do not interpret the lower rates of ADHD and anxiety in children with intellectual disability as evidence that these conditions are less common in this group. The authors suggest this likely reflects diagnostic overshadowing, where ID explains symptoms, or difficulties in detecting internal states like anxiety in individuals with limited verbal ability.