Attention deficit-hyperactivity disorder among mentally retarded children.

Taub et al. (1994) compared ADHD symptoms in kids with and without intellectual disability. They used the Conners Teacher Rating Scale to see if low IQ changed the ADHD picture.

The study looked at children with ID, typical-IQ children with ADHD, and kids without either condition. Teachers filled out the same 39-item checklist for all groups.

ADHD looked mostly the same regardless of IQ level. The core hyperactive-impulsive and inattentive symptoms showed up similarly on teacher ratings.

Two differences stood out. Children with ID plus ADHD scored higher on anxiety items. Typical-IQ children with ADHD were rated as more asocial by their teachers.

Farrant et al. (1998) extended this work to adults, finding about 1 in 7 with severe ID also meet ADHD criteria. This suggests the ADHD-ID link persists across the lifespan.

Matson et al. (2011) tracked children longitudinally and found ADHD sticks around longer when ID is present. Their data show similar symptom trajectories but slower improvement in the ID group.

Lancioni et al. (2009) looked at adults with mild ID plus ADHD and found extra attention problems beyond what IQ alone would predict. This seems to contradict our target paper, but the difference is severity. The 1994 study mixed ID levels, while 2009 focused on mild ID where subtle attention deficits become clearer.

When you assess a child with both ADHD and ID, don't assume all behavior problems come from one condition. Watch for anxiety symptoms that might need separate treatment. Also check social skills - typical-IQ kids with ADHD may need different social interventions than their peers with ID. Use the same rating scales for both groups, but interpret anxiety and social items differently based on IQ level.