Neuropsychological characteristics of adults with comorbid ADHD and borderline/mild intellectual disability.

Lancioni et al. (2009) compared adults who have both ADHD and mild-borderline intellectual disability to adults with ADHD alone.

They used a neuropsych test battery that measured selective attention and commission errors.

IQ scores were held constant so any extra attention problems could be blamed on the ID, not low IQ.

The double-diagnosis group made more errors and scored lower on selective attention even after IQ was controlled.

In plain words, the ID plus ADHD combo created an extra attention hit beyond what IQ alone predicts.

McClain et al. (2017) saw the same pattern in kids: ADHD symptoms look milder when ID is present, yet hidden attention deficits remain.

Waldron et al. (2023) zoom out in a big review and warn that attention in ID must be judged against mental-age norms, not calendar age.

The three papers line up: expect subtler but real attention gaps in ID, so use developmental level when you interpret scores.

When you test an adult with ADHD and mild ID, do not shrug off poor attention scores as "just low IQ."

Plan longer response-time windows, break tasks into smaller chunks, and teach self-monitoring skills.

These clients need ADHD treatment plus ID-friendly supports; one size will not fit both conditions.