Abstract
Patients with attention deficit-hyperactivity disorder (ADHD) exhibit difficulties in multiple attentional functions. Although high heritability rates suggest a strong genetic impact, aetiological pathways from genes and environmental factors to the ADHD phenotype are not well understood. Tracking the time course of deviant task processing using event-related electrophysiological brain activity should characterize the impact of familiality on the sequence of cognitive functions from preparation to response control in ADHD. Method Preparation and response control were assessed using behavioural and electrophysiological parameters of two versions of a cued continuous performance test with varying attentional load in boys with ADHD combined type (n=97), their non-affected siblings (n=27) and control children without a family history of ADHD (n=43). Children with ADHD and non-affected siblings showed more variable performance and made more omission errors than controls. The preparatory Cue-P3 and contingent negative variation (CNV) following cues were reduced in both ADHD children and their non-affected siblings compared with controls. The NoGo-P3 was diminished in ADHD compared with controls whilst non-affected siblings were located intermediate but did not differ from both other groups. No clear familiality effects were found for the Go-P3. Better task performance was further associated with higher CNV and P3 amplitudes. Impairments in performance and electrophysiological parameters reflecting preparatory processes and to some extend also for inhibitory response control, especially under high attentional load, appeared to be familially driven in ADHD and may thus constitute functionally relevant endophenotypes for the disorder.
Highlights
Attention deficit-hyperactivity disorder (ADHD) goes hand in hand with multiple dysfunctions in neuronal networks responsible for attention and response control (Pennington & Ozonoff, 1996 ; Castellanos &Tannock, 2002)
It is expected that endophenotypes show larger and more specific genetic effects than diagnostic phenotypes (Doyle et al 2005) and may serve as useful intermediate constructs that explain the heterogeneity of the ADHD phenotype (Buitelaar, 2005 ; Banaschewski et al 2007 ; Rommelse et al 2007a)
We showed that action monitoring as reflected by several performance and electrophysiological parameters was impaired in boys with ADHD and intermediate in their non-affected siblings compared with controls without a family history of ADHD (Albrecht et al 2008, 2009)
Summary
Attention deficit-hyperactivity disorder (ADHD) goes hand in hand with multiple dysfunctions in neuronal networks responsible for attention and response control (Pennington & Ozonoff, 1996 ; Castellanos &Tannock, 2002). It is expected that endophenotypes show larger and more specific genetic effects than diagnostic phenotypes (Doyle et al 2005) and may serve as useful intermediate constructs that explain the heterogeneity of the ADHD phenotype (Buitelaar, 2005 ; Banaschewski et al 2007 ; Rommelse et al 2007a). We showed that action monitoring as reflected by several performance and electrophysiological parameters was impaired in boys with ADHD and intermediate in their non-affected siblings compared with controls without a family history of ADHD (Albrecht et al 2008, 2009) Deficits in these parameters may be a consequence of specific genes or environmental factors that are shared in the families.
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