Intergenerational transmission of adult to child ADHD in a population-based cohort study

Attention deficit hyperactivity disorder (ADHD) ischaracterized by a persistent pattern of inattention and/orhyperactivity-impulsivity that interferes with functioning. Previous twin andfamily studies have shown moderate... [ view full abstract ]

Attention deficit hyperactivity disorder (ADHD) ischaracterized by a persistent pattern of inattention and/orhyperactivity-impulsivity that interferes with functioning. Previous twin andfamily studies have shown moderate estimates of heritability for adult ADHD andhigh estimates of heritability of child ADHD. Across these studies, there hasbeen little evidence of substantial effects of environmental factors shared bysiblings. However, there is to date comparatively little knowledge on to whatextent adult and child ADHD have common genetic risk factors.

By using the Intergenerational Transmission of Risk (IToR)study, a twin-family subsample of the Norwegian Mother and Child Cohort study,we will estimate: 1) heritability of adult ADHD, 2) heritability of child ADHD,3) genetic transmission of adult ADHD to child ADHD, 4) genetic factorsspecific to child ADHD, and 5) possible direct effects of parental ADHD tochild ADHD. To estimate such parameters, we will apply an extended children oftwin model on the IToR dataset comprising a large number of sibling/twinfamilies.

The results will inform on the biological underpinnings ofthe similar phenomena of adult and child ADHD. Our estimates of geneticinnovation across age is of importance to molecular genetic studies wheredifferent age groups are often used in a single sample.