title: Polymorphisms in dopamine system genes are associated with individual differences in attention in infancy.
abstract: Knowledge about the functional status of the frontal cortex in infancy is limited. This study investigated the effects of polymorphisms in four dopamine system genes on performance in a task developed to assess such functioning, the Freeze-Frame task, at 9 months of age. Polymorphisms in the catechol-O-methyltransferase (COMT) and the dopamine D4 receptor (DRD4) genes are likely to impact directly on the functioning of the frontal cortex, whereas polymorphisms in the dopamine D2 receptor (DRD2) and dopamine transporter (DAT1) genes might influence frontal cortex functioning indirectly via strong frontostriatal connections. A significant effect of the COMT valine(1)methionine (Val 158 Met) polymorphism was found. Infants with the Met/Met genotype were significantly less distractible than infants with the Val/Val genotype in Freeze-Frame trials presenting an engaging central stimulus. In addition, there was an interaction with the DAT1 3; variable number of tandem repeats polymorphism; the COMT effect was present only in infants who did not have two copies of the DAT1 10-repeat allele. These findings indicate that dopaminergic polymorphisms affect selective aspects of attention as early as infancy and further validate the Freeze-Frame task as a frontal cortex task.
authors.affiliation: Centre for Brain and Cognitive Development, Birkbeck, University of London, London, United Kingdom. karla.holmboe@kcl.ac.uk
authors.forename: Karla
authors.initials: K
authors.lastname: Holmboe
authors.forename: Zsofia
authors.initials: Z
authors.lastname: Nemoda
authors.forename: R M Pasco
authors.initials: RM
authors.lastname: Fearon
authors.forename: Gergely
authors.initials: G
authors.lastname: Csibra
authors.forename: Maria
authors.initials: M
authors.lastname: Sasvari-Szekely
authors.forename: Mark H
authors.initials: MH
authors.lastname: Johnson
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001288:Attention / Q000502:physiology*; D002394:Catechol O-Methyltransferase / Q000235:genetics; D015331:Cohort Studies; D004298:Dopamine / Q000235:genetics* / Q000378:metabolism; D050483:Dopamine Plasma Membrane Transport Proteins / Q000235:genetics; D005260:Female; D005787:Gene Frequency; D055106:Genome-Wide Association Study / Q000379:methods; D005838:Genotype; D006801:Humans; D007206:Individuality; D007223:Infant; D008297:Male; D018598:Minisatellite Repeats / Q000235:genetics; D009483:Neuropsychological Tests; D010287:Parent-Child Relations; D010775:Photic Stimulation / Q000379:methods; D011110:Polymorphism, Genetic / Q000235:genetics*; D017447:Receptors, Dopamine D1 / Q000235:genetics; D017448:Receptors, Dopamine D2 / Q000235:genetics
chemical_list: D050483:Dopamine Plasma Membrane Transport Proteins; D017447:Receptors, Dopamine D1; D017448:Receptors, Dopamine D2; D002394:Catechol O-Methyltransferase; D004298:Dopamine