The prevalence of learning disability in a Health and Social Services Board in Northern Ireland.
Counting every list in one Northern Ireland board showed severe learning disability at about 1% of teens, double the usual textbook figure.
01Research in Context
What this study did
Workers counted every 15- to 19-year-old with severe learning disability in one Northern Ireland health board.
They used IQ below 50 as the cut-off and checked school, clinic, and social-service lists.
What they found
About 8 to 10 teenagers in every 1,000 had severe learning disability. That is roughly 1%.
Half of these teens still lived with both parents, and mothers were the main carers.
How this fits with other research
Kapoor et al. (2024) asked the same question across all of India and found far lower numbers: about 1 to 2 per 1,000. The gap looks huge, but India used stricter school-record rules and counted only diagnosed cases, so many milder cases were missed.
Pitetti et al. (2007) in Finland used several government registers at once and reached 7 per 1,000, close to the Northern Ireland rate. Their work shows that linking health, school, and social files catches more people than any single list.
Lai et al. (2012) tracked Taiwanese children and saw the rate inch up each year. Like the Northern Ireland study, they found boys out-numbered girls, hinting that the true count keeps rising when you look harder.
Why it matters
If you plan services, do not rely on one database. Combine school special-ed lists, clinic files, and social-service records to avoid under-counting. Expect roughly 1% severe ID in teens, and remember most live at home with mum as the primary carer. Build respite and parent-training slots for that family shape, not just residential placements.
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02At a glance
03Original abstract
The Southern Health and Social Services Board is one of four in the province and encompasses three administrative areas. The survey included ascertained mild cases of learning disability, and both ascertained and unascertained individuals functioning at levels below IQ 50. The prevalence of mild learning disability is within the limits reported in the literature and is discussed in the context of the 'new morbidity'. However, the rates of severe learning disability (IQ < 50) in all three areas are high--between 7.9 and 10.2 per 1000 in the 15-19-years-old age group--and confirm the findings of an earlier survey. Half of all cases live at home in 'intact' families. In families with a sole carer, the mother is seven times more likely to fill the role than the father.
Journal of intellectual disability research : JIDR, 1996 · doi:10.1046/j.1365-2788.1996.801801.x