Peer-reviewed article
Psychopathology from childhood to adolescence in children with and without Mild Intellectual Disability (MID): a comparison across three MID operationalizations.
Dogukan Koc, Maurits Masselink, Stefania Barzeva, Daan H G Hulsmans, Nanda N J Rommelse et al. ·
Summary
Written by AI, not yet AICS's view · claude-haiku-4-5-20251001This study followed 4,643 children from the Netherlands from ages 1.5 to 15 years to compare behavioural and emotional problems in children with mild intellectual disability (MID) against matched controls. Children with MID showed higher levels of ADHD, affective, and autistic problems than children without MID, with the extent of problems depending on how MID was defined. The broadest definition of MID, including borderline intellectual disability (IQ 75-85 with adaptive functioning impairment), showed the highest problem levels, and differences increased over time.
Key points
- Children with MID across all definitions showed elevated behavioural and emotional problems compared to matched controls from early childhood through adolescence
- The broadest MID definition (IQ ≤85 with adaptive functioning impairment) identified children with the highest levels of ADHD, affective, and autistic problems
- Children with borderline intellectual disability (IQ 75-85) may have particularly elevated mental health problems
- ADHD trajectories were unfavourable in children with the two narrower MID definitions even without baseline differences
- Mental health problem levels depend significantly on how mild intellectual disability is operationalized clinically
Limitations
The study is observational and based on parent-reported problems only, which may not capture the full picture of children's psychological functioning. The findings apply to a Dutch population and may not generalise to other countries with different healthcare and educational systems.
Abstract
The DSM-5(-TR) expanded the definition of Mild Intellectual Disability (MID) to include adaptive functioning (AF) alongside intelligence quotient (IQ). In this population-based study, we examined behavioural and emotional problems in children with MID and matched controls from early childhood to adolescence. We evaluated how three operationalizations of MID, varying by IQ and AF, influence outcomes. Cognitive assessments and parent-reported problems from 4,643 children from 1.5 to 15 years (T1 to T5) in the Generation R Study were used. MID was defined as: (1) IQ ≤ 75; (2) IQ ≤ 75 with impairments in AF; (3) IQ ≤ 85 with impairments in AF. Propensity score matching ensured comparable MID and non-MID groups. Linear mixed-effects models were employed to assess multiple domains of psychopathology over time. Across all MID definitions, children with MID exhibited elevated behavioural and emotional problems compared to matched controls. Children meeting the criteria for MID3, the broadest definition, showed the highest problem levels, with elevated ADHD (β = 0.37, pFDR < 0.001), affective (β = 0.25, pFDR < 0.001), and autistic problem scores (β = 0.25, pFDR < 0.001) at baseline, with differences widening over time. Children with MID1 and MID2 also displayed unfavourable ADHD trajectories, although no baseline differences were observed. The findings suggest the extent of mental health problems depends on how MID is operationalized and suggest that psychopathology may be particularly present in children with borderline intellectual disability, 75 ≤ IQ ≤ 85.