In one sentence
A study of 314 Swedish twins suggests that autism and intellectual disability are linked to everyday skill challenges even after accounting for shared genetics and environment, while ADHD’s link to those challenges may be explained largely by genetic factors.
What the researchers did
Adaptive functioning means the practical skills children use in daily life — communication, self-care, social participation, and community routines. Challenges in these areas are part of the diagnostic picture for many neurodevelopmental conditions, but it can be hard to separate diagnosis effects from genetics, co-occurring conditions, and family environment.
Researchers studied 314 twin pairs aged 8–21 in Sweden, including identical and fraternal twins. Parents rated adaptive functioning using the Adaptive Behavior Assessment System, second edition. The team looked at diagnoses of autism, ADHD, and intellectual disability, along with other psychiatric conditions. They first compared twins across different families, then compared twins within the same pair to adjust for shared genetics and upbringing.
What they found
Across twin pairs, each neurodevelopmental condition was independently associated with greater adaptive functioning challenges. Having more than one condition was linked to more difficulty: more diagnoses meant more everyday support needs.
Among autistic participants, older age was associated with more adaptive challenges. When researchers compared identical twins within pairs — who share all their genes — the link between autism and adaptive difficulties remained, as did the link for intellectual disability. For ADHD, however, the association with adaptive challenges weakened and was no longer significant among identical twins after full genetic adjustment, suggesting genetic factors may explain much of ADHD’s link to daily living skills in this sample.
What this means for families and therapists
For autistic children and those with intellectual disability, everyday skills may need ongoing, practical support that goes beyond a single therapy room. Teams should plan for communication, self-care, and community participation across settings, not assume that support needs will simply fade with age.
For children with ADHD, genetic influences may matter, but structured routines, clear expectations, and skill coaching still help in real life. Parents can ask clinicians which daily skills to prioritise and how to practise them at home and school.
Because co-occurring conditions add to difficulty, comprehensive assessment matters. When several diagnoses are present, therapy plans should address the combined picture rather than treating each label in isolation.
Limitations and what we don't know yet
The sample included 314 twins from Sweden, so findings may not apply everywhere. Adaptive functioning was measured by parent report only, which may not capture performance in every setting.
This was a snapshot study, so it cannot prove cause and effect or show how skills change over time. Twin designs reduce but do not eliminate all confounding factors, such as prenatal influences or gene–environment interactions.
This is a simplified summary of Neurodevelopmental conditions and adaptive functioning - a co-twin control study by Isaksson J, Eklund F, Remnélius KL, Black MH, Bölte S, Journal of child psychology and psychiatry, and allied disciplines (2025).
Source license: CC-BY.
This is not medical advice. Please consult a qualified healthcare professional before making treatment decisions.