BACKGROUND: Impairments in executive functioning (EF) and intelligence quotient (IQ) are frequently observed in children with attention deficit hyperactivity disorder (ADHD). The aim of this paper was twofold: first, to examine whether both domains are viable endophenotypic candidates for ADHD and second to investigate whether deficits in both domains tend to co-segregate within families. METHOD: A large family-based design was used, including 238 ADHD families (545 children) and 147 control families (271 children). Inhibition, visuospatial and verbal working memory, and performance and verbal IQ were analysed. RESULTS: Children with ADHD, and their affected and non-affected siblings were all impaired on the EF measures and verbal IQ (though unimpaired on performance IQ) and all measures correlated between siblings. Correlations and sibling cross-correlations were not significant between EF and IQ, though they were significant between the measures of one domain. Group differences on EF were not explained by group differences on IQ and vice versa. The discrepancy score between EF and IQ correlated between siblings, indicating that siblings resembled each other in their EF-IQ discrepancy instead of having generalized impairments across both domains. Siblings of probands who had an EF but not IQ impairment, showed a comparable disproportionate lower EF score in relation to IQ score. The opposite pattern was not significant. CONCLUSIONS: The results supported the viability of EF and IQ as endophenotypic candidates for ADHD. Most findings support an independent familial segregation of both domains. Within EF, similar familial factors influenced inhibition and working memory. Within IQ, similar familial factors influenced verbal and performance IQ.
BACKGROUND: Impairments in executive functioning (EF) and intelligence quotient (IQ) are frequently observed in children with attention deficit hyperactivity disorder (ADHD). The aim of this paper was twofold: first, to examine whether both domains are viable endophenotypic candidates for ADHD and second to investigate whether deficits in both domains tend to co-segregate within families. METHOD: A large family-based design was used, including 238 ADHD families (545 children) and 147 control families (271 children). Inhibition, visuospatial and verbal working memory, and performance and verbal IQ were analysed. RESULTS:Children with ADHD, and their affected and non-affected siblings were all impaired on the EF measures and verbal IQ (though unimpaired on performance IQ) and all measures correlated between siblings. Correlations and sibling cross-correlations were not significant between EF and IQ, though they were significant between the measures of one domain. Group differences on EF were not explained by group differences on IQ and vice versa. The discrepancy score between EF and IQ correlated between siblings, indicating that siblings resembled each other in their EF-IQ discrepancy instead of having generalized impairments across both domains. Siblings of probands who had an EF but not IQ impairment, showed a comparable disproportionate lower EF score in relation to IQ score. The opposite pattern was not significant. CONCLUSIONS: The results supported the viability of EF and IQ as endophenotypic candidates for ADHD. Most findings support an independent familial segregation of both domains. Within EF, similar familial factors influenced inhibition and working memory. Within IQ, similar familial factors influenced verbal and performance IQ.
Authors: Jonna Kuntsi; Alexis C Wood; Frühling Rijsdijk; Katherine A Johnson; Penelope Andreou; Björn Albrecht; Alejandro Arias-Vasquez; Jan K Buitelaar; Gráinne McLoughlin; Nanda N J Rommelse; Joseph A Sergeant; Edmund J Sonuga-Barke; Henrik Uebel; Jaap J van der Meere; Tobias Banaschewski; Michael Gill; Iris Manor; Ana Miranda; Fernando Mulas; Robert D Oades; Herbert Roeyers; Aribert Rothenberger; Hans-Christoph Steinhausen; Stephen V Faraone; Philip Asherson Journal: Arch Gen Psychiatry Date: 2010-11
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Authors: Anoek M Oerlemans; Katharina Droste; Daphne J van Steijn; Leo M J de Sonneville; Jan K Buitelaar; Nanda N J Rommelse Journal: J Autism Dev Disord Date: 2013-12
Authors: A C Wood; F Rijsdijk; K A Johnson; P Andreou; B Albrecht; A Arias-Vasquez; J K Buitelaar; G McLoughlin; N N J Rommelse; J A Sergeant; E J S Sonuga-Barke; H Uebel; J J van der Meere; T Banaschewski; M Gill; I Manor; A Miranda; F Mulas; R D Oades; H Roeyers; A Rothenberger; H C Steinhausen; S V Faraone; P Asherson; J Kuntsi Journal: Psychol Med Date: 2010-06-04 Impact factor: 7.723
Authors: Siri D S Noordermeer; Marjolein Luman; Jan K Buitelaar; Catharina A Hartman; Pieter J Hoekstra; Barbara Franke; Stephen V Faraone; Dirk J Heslenfeld; Jaap Oosterlaan Journal: J Atten Disord Date: 2015-10-20 Impact factor: 3.256
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