title: Temporal changes in incidence and prevalence of intellectual disability between two birth cohorts in Northern Finland.
abstract: We followed two separate, genetically homogeneous cohorts of children born in 1966 (n = 11,965) and 1985-1986 (n = 9,432) in Northern Finland to determine temporal changes in the incidence and prevalence of subcategories of intellectual disability within the same geographic area. The children were followed up to the age of 11.5 years. Similar study design, data ascertainment methods, and definition of intellectual disability were used. There was no change in the total incidence (12.62/1,000 in each) or in total prevalence (11.03/1,000 vs. 11.23/1,000) of intellectual disability. However, in the subcategories of intellectual disability, there was a shift from severe and moderate towards mild; whereas profound intellectual disability remained at the same level. The temporal changes followed generally similar patterns by gender.
authors.affiliation: University of Oulu, Department of Public Health Science and General Practice, Finland. ulla.heikura@oulu.fi
authors.forename: Ulla
authors.initials: U
authors.lastname: Heikura
authors.forename: Anja
authors.initials: A
authors.lastname: Taanila
authors.forename: Päivi
authors.initials: P
authors.lastname: Olsen
authors.forename: Anna-Liisa
authors.initials: AL
authors.lastname: Hartikainen
authors.forename: Lennart
authors.initials: L
authors.lastname: von Wendt
authors.forename: Marjo-Riitta
authors.initials: MR
authors.lastname: Järvelin
mesh_terms: D000293:Adolescent; D002391:Catchment Area, Health; D015331:Cohort Studies; D005260:Female; D005387:Finland / Q000453:epidemiology; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008607:Intellectual Disability / Q000175:diagnosis / Q000453:epidemiology*; D008297:Male; D015995:Prevalence; D011594:Psychometrics / Q000379:methods; D012720:Severity of Illness Index; D017678:Sex Distribution; D013997:Time Factors