Prevalence of autism in Iceland.
Autism cases in Iceland doubled across birth cohorts, and later work shows adults with ID are still missed—expect more clients and plan services now.
01Research in Context
What this study did
Doctors counted every child born in Iceland from 1974 to 1993 who later got an autism diagnosis.
They split the kids into two groups: 1974-1983 and 1984-1993. Then they compared how many kids in each group had autism.
What they found
Autism jumped from 3.the kids per 10,000 in the first group to 8.6 per 10,000 in the second group.
That is more than double in just ten years.
How this fits with other research
Smith et al. (2010) looked again in Iceland, but only at adults with severe intellectual disability. They found 1 in 5 also had autism—twice what services had noticed.
Together the two papers show the count keeps rising and many adults are still missed.
Mahdi et al. (2018) widened the lens. They list 110 ways autism shows up, not just numbers. The rising count plus the long list means you need both head-counts and full-function profiles.
Why it matters
Prevalence doubled and adults are under-counted. You will see more clients every year. Start planning now: bigger caseloads, staff hiring, funding requests, and adult services.
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02At a glance
03Original abstract
This clinic-based study estimated the prevalence of autism in Iceland in two consecutive birth cohorts, subjects born in 1974-1983 and in 1984-1993. In the older cohort classification was based on the ICD-9 in 72% of cases while in the younger cohort 89% of cases were classified according to the ICD-10. Estimated prevalence rates for Infantile autism/Childhood autism were 3.8 per 10,000 in the older cohort and 8.6 per 10,000 in the younger cohort. The characteristics of the autistic groups are presented in terms of level of intelligence, male:female ratio, and age at diagnosis. For the younger cohort scores on the Autism Diagnostic Interview-Revised and the Childhood Autism Rating Scale are reported as well. Results are compared with a previous Icelandic study and recent population-based studies in other countries based on the ICD-10 classification system. Methodological issues are discussed as well as implications for future research and service delivery.
Journal of autism and developmental disorders, 2001 · doi:10.1023/a:1010795014548