Does weak working memory explain ADHD after orphanage care?
Children who spent early life in Romanian orphanages had more ADHD symptoms at age 12, and their poorer working memory statistically accounted for much of that link, while planning did not.
Source
Reduced Working Memory Mediates the Link between Early Institutional Rearing and Symptoms of ADHD at 12 Years
Study at a glance
- Design
- Cohort — Age-12 wave of a longitudinal cohort (originally an RCT of foster care vs institutional care) comparing ever-institutionalized with never-institutionalized children, with mediation analysis of concurrent CANTAB and teacher-rated ADHD data.
- N
- N=107 · 107 children assessed at 12 years: 73 ever institutionalized (foster-care and care-as-usual groups combined) and 34 never institutionalized community controls.
- Population
- Romanian children recruited in infancy from Bucharest institutions, plus community children recruited via GP offices.
- Outcome
- Teacher-rated inattention and impulsivity (HBQ); mediators were CANTAB working memory, planning and set-shifting indices.
Structured fields used in claim comparison tables when every cited study has a complete layer.
What they did
The researchers followed children from the Bucharest Early Intervention Project, who had been randomly assigned in infancy either to stay in institutions or move to foster care, alongside never-institutionalized community children. At age 12, 107 children completed computerized tests of working memory, planning and set-shifting, and their teachers rated inattention and impulsivity. Because foster care had no effect on these outcomes, the two institutionalized arms were combined and compared with controls, and mediation models tested which executive functions carried the link, adjusting for birth weight and gender.
What they found
Children with a history of institutional care had clearly higher teacher-rated inattention and impulsivity and did worse on all the executive function tasks. Working memory indices jointly mediated the effect of institutionalization on both inattention and impulsivity, cutting the total effect by 48.6% and 66.5% respectively until it was no longer significant. Planning, although also impaired, did not significantly mediate either outcome, and set-shifting was not linked to ADHD symptoms at all. Removing Roma children did not change the institutionalization effects.
The limits
What it doesn't show
Working memory and ADHD symptoms were measured at the same time, so the mediation model cannot establish that poor working memory causes the symptoms rather than the reverse. ADHD was measured only by teacher questionnaire, not clinical interview. Prenatal, genetic and early medical factors were not measured and could contribute to both deficits. The foster-care comparison was null here, so the study cannot say whether earlier placement would have prevented the pathway.
Key terms
- Institutional rearing
- Being raised in an orphanage-type institution, typically involving severe psychosocial and sensory deprivation.
- Mediation analysis
- A statistical test of whether a third variable (the mediator) carries part of the association between a predictor and an outcome.
- Indirect effect
- The part of a predictor's effect that passes through the mediator; here tested with bootstrapped confidence intervals that must exclude zero.
- Working memory
- The ability to hold and manipulate information over short periods, measured here with CANTAB memory tasks.
- Executive functions
- Higher-order control skills such as working memory, planning, inhibition and set-shifting that guide goal-directed behaviour.
Flashcards
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Quiz yourself
Which cognitive ability mediated the link between institutional rearing and ADHD symptoms?
Common questions
Why were the foster-care and care-as-usual groups combined?
At age 12 the two randomized groups did not differ on ADHD symptoms or executive function, so the authors compared all ever-institutionalized children with never-institutionalized children.
Does this prove orphanage care causes ADHD through working memory?
Not definitively. Institutional history came first, but working memory and ADHD were measured together, and genetic or prenatal factors were not controlled.
What practical implication do the authors draw?
They suggest working memory training might reduce symptoms in these children, though no study has yet tested it in this population.
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