Comparisons of IQ in Children With and Without Cochlear Implants: Longitudinal Findings and Associations With Language.
Ivette Cejas, Christine M Mitchell, Michael Hoffman and 1 others
PMID 29624538WHAT IT FOUND
Children with cochlear implants scored in the average range on school-age IQ tests, but below hearing peers.
Their IQ scores were more closely linked to spoken language than to hearing status or mother's education.
Key findings
01At school age, children with cochlear implants scored lower than hearing peers on the nonverbal IQ indices, but both groups averaged within the normal range.
02Spoken language scores were the strongest correlate of school-age IQ; when language was included in regression models, hearing status and mother's education no longer predicted IQ.
03In a small exploratory subgroup, children with cochlear implants and severe additional comorbidities scored lower at baseline and on school-age processing speed than children with cochlear implants without those comorbidities.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
The hearing peers had higher maternal education and household income than the children with cochlear implants, so family advantage likely contributed to the IQ and language gaps. The cochlear implant group was older than the hearing group when the school-age IQ test was given, mean 8.5 versus 7.7 years, so age at testing may have affected scores. The CI + Comorbidities group had only 11 children, and the comparison was exploratory, so differences should not be treated as stable findings. The WISC indices were called nonverbal, but instructions and comprehension still depended on spoken language, which can lower scores in children with hearing loss. The tests used at baseline and school age were different, and the study compared scores across those tests rather than using the same measure at both ages. Norms for the WISC and CASL are based on hearing children, not children with hearing loss.
Declared interests
The study was supported by NIH/NIDCD grant R01DC004797. Dr. Cejas reported ties to AG Bell, a pediatric advisory board, Advanced Bionics, and NIDCD.
The easy way to misread this
Do not conclude that cochlear implants cause lower IQ. The children with cochlear implants still scored in the average range, the hearing comparison group had higher maternal education and income, and the study did not assign children to implants or hearing. Do not use early pre-implant IQ alone to predict school-age cognition, especially when language ability is not considered.