Inhibition of Motor Responses in Siblings Concordant and Discordant for Attention Deficit Hyperactivity Disorder

Abstract

Impaired inhibitory control aggregates in the family members of individuals with ADHD and may serve as an indicator of genetic vulnerability to the disorder.

Support for an independent familial segregation of executive and intelligence endophenotypes in ADHD families

“…The findings of impaired EF in children with ADHD are in line with most previous studies on inhibition, visuospatial and verbal working memory in patients with ADHD (Oosterlaan & Sergeant, 1996 ;Oosterlaan et al 1998 ;Nigg, 1999 ;Martinussen et al 2005). Much less is known about EF in relatives of children with ADHD, but our results are in line with previous studies on EF and other cognitive difficulties in non-affected siblings (Crosbie & Schacher, 2001 ;Slaats-Willemse et al 2003 ;Doyle et al 2005a ;Schachar et al 2005 ;Waldman et al 2006 ;Rommelse et al 2007 ;Bidwell et al 2007). The results suggest that deficits in EF form key neuropsychological endophenotypic candidates, as has been previously suggested (Castellanos & Tannock, 2002).…”

“…More promising results have been reported by Waldman et al (2006), showing that various EF measures are impaired in non-affected siblings and correlated between siblings ; also, a study focusing on twins discordant for ADHD reported on various EF measures as endophenotypic candidates (Bidwell et al 2007). Studies that have specifically targeted inhibition as a cognitive endophenotype have also reported promising results : two studies reported non-affected siblings as performing intermediately between their affected siblings and controls (SlaatsWillemse et al 2003 ;Schachar et al 2005) and a third study reported that poor inhibition in children with ADHD was related to a higher prevalence of ADHD among their relatives (Crosbie & Schachar, 2001). Subtle problems in interference control have been reported in non-affected relatives of girls with ADHD (Doyle et al 2005a) and significant correlations have been found for inhibitory control between affected siblings (Slaats-Willemse et al 2005).…”

Testing for Neuropsychological Endophenotypes in Siblings Discordant for Attention-Deficit/Hyperactivity Disorder

“…The finding of slower and more variable response speed in siblings of ADHD probands is consistent with previous results showing that unaffected relatives might have difficulty sustaining sufficient cognitive activation, despite not showing the full behavioral manifestation of ADHD (23). The finding of an SSRT deficit is also consistent with other studies (23,25,26) that have measured SSRT in unaffected relatives. Moreover, Durston et al (63) measured the neuroanatomy of unaffected siblings of ADHD probands and found that the unaffected siblings have reduced right prefrontal gray matter volume relative to control subjects.…”

“…Two studies focused exclusively on response inhibition and found that small samples of unaffected siblings of ADHD probands did not differ from their ADHD siblings on measures of response inhibition (25,26). Nigg et al (23) examined performance of relatives of ADHD probands on measures of a broader range of neuropsychological tasks.…”

Converging Evidence for a Fronto-Basal-Ganglia Network for Inhibitory Control of Action and Cognition: Figure 1.

“…Impaired stopping performance appears to aggregate in the family members of individuals with ADHD and may serve as an indicator of genetic vulnerability to the disorder (Crosbie and Schachar, 2001;Schachar et al, 2005). Consistent with this, right IFC gray matter and functional activation is reduced in unaffected siblings of children and adolescents with a diagnosis of ADHD (Durston et al, 2004(Durston et al, , 2006.…”