ADHD in Dutch adults: Heritability and linkage study

Abstract

Attention deficit/hyperactivity disorder (ADHD) is a neurodevelopmental phenotype that persists into adulthood. This study investigated the heritability of inattentive and hyperactive symptoms and of total ADHD symptomatology load (ADHD index) in adults and performed linkage scans for these dimensions. Data on sibling pairs and their family members from the Netherlands Twin Register with genotype and phenotype data for inattention, hyperactivity and ADHD index (∼750 sib-pairs) were analyzed. Phenotypes were assessed with the short self-report form of the Conners' Adult ADHD Rating Scales (CAARS). Heritabilities were estimated in SOLAR under polygenic models. Genome-wide linkage scans were performed using variance components (VC) in MERLIN and MINX and model-based linkage analysis was carried out in MENDEL with empirical evaluation of the results via simulations. Heritability estimates for inattention, hyperactivity and ADHD index were 35%, 23%, and 31%, respectively. Chromosomes 18q21.31-18q21.32 (VC LOD = 4.58, p(emp) = 0.0026) and 2p25.1 (LOD = 3.58, p(emp) = 0.0372) provided significant evidence for linkage for inattention and the ADHD index, respectively. The QTL on chromosome 2p25.1 also showed suggestive linkage for hyperactivity. Two additional suggestive QTLs for hyperactivity and the ADHD index shared the same location on chromosome 3p24.3-3p24.1. Finally, a suggestive QTL on 8p23.3-8p23.2 for hyperactivity was also found. Heritability of inattention, hyperactivity and total ADHD symptoms is lower in adults than in children. Chromosomes 18q and 2p are likely to harbor genes that influence several aspects of adult ADHD.

Adoptive parent hostility and children’s peer behavior problems: Examining the role of genetically informed child attributes on adoptive parent behavior.

“…Low behavioral motivation, low social motivation, and inattention have been shown to be moderately heritable in both adults and children (Goldsmith, Buss, & Lemery, 1997; Saviouk et al, 2011; Sherman et al, 1997; Silberg et al, 2005; Takahashi et al, 2007), indicating possible parent-to-child transmission of these characteristics in biologically-related parents and children. Such parent characteristics (i.e., low behavioral motivation) may therefore influence child characteristics (i.e., low social motivation) through shared genetic influences.…”

ADHD-like behavior and entrepreneurial intentions

“…Though the exact causes of clinical ADHD are not known, medical studies find consistent evidence that the disorder has a neurobiological origin (Mathis et al 2014) and is genetically determined (Thapar et al 1999;Mathis et al 2014) with genetics contributing to about 60-75 % of cases (Cortese 2012;Faraone et al 2005). Despite the fact that ADHD appears quite stable and the majority of adolescents continue to experience its symptoms in (young) adulthood (Biederman et al 2007;Kan et al 2013;Saviouk et al 2011), most of what we know about its consequences for individual behavior is derived from research with children. Far less attention is paid to adult decision making and behavior (Young 2000).…”

Borderline personality traits and adult attention‐deficit hyperactivity disorder symptoms: A genetic analysis of comorbidity

“…Familial clustering of adult ADHD was reported by Antshel et al [2009] who found in a sample of high IQ adults that ADHD was more prevalent in first degree relatives of adults with ADHD relative to controls (28% in family members of adults with ADHD versus 5% in family members of IQ matched controls). Only two twin family studies till date looked at the genetic influences on adult ADHD [Boomsma et al, 2010; Saviouk et al, 2011]. Both studies used the screening version of the Conners’ Adult Rating Scales [CAARS-S:SV; Conners et al, 1999] to assess inattentive and hyperactive symptoms and likely ADHD diagnosis(ADHD-Index) in a large sample of Dutch twins and their family members.…”