ADHD in Dutch adults: heritability and linkage study

Area of Science:

• Genetics
• Neuroscience
• Psychiatry

Background:

• Attention deficit/hyperactivity disorder (ADHD) is a neurodevelopmental condition that often persists into adulthood.
• Understanding the genetic underpinnings of adult ADHD is crucial for developing targeted interventions.

Purpose of the Study:

• To investigate the heritability of inattentive and hyperactive symptoms in adults.
• To perform genome-wide linkage scans to identify chromosomal regions associated with adult ADHD dimensions.

Main Methods:

• Analysis of sibling pairs and family members from the Netherlands Twin Register (approx. 750 sib-pairs).
• Phenotypic assessment using the Conners' Adult ADHD Rating Scales (CAARS).
• Heritability estimation using SOLAR and genome-wide linkage scans using MERLIN, MINX, and MENDEL.

Main Results:

• Heritability estimates for inattention, hyperactivity, and the ADHD index were 35%, 23%, and 31%, respectively.
• Significant linkage for inattention found on chromosome 18q21.31-18q21.32 (LOD=4.58).
• Significant linkage for the ADHD index found on chromosome 2p25.1 (LOD=3.58), with suggestive linkage for hyperactivity.
• Additional suggestive quantitative trait loci (QTLs) identified on chromosomes 3p24.3-3p24.1 and 8p23.3-8p23.2.

Conclusions:

• Heritability of ADHD symptoms is lower in adults compared to children.
• Chromosomes 18q and 2p are implicated in harboring genes that influence adult ADHD.
• These findings provide insights into the genetic architecture of adult ADHD.