D2.4 Reduced grey matter concentrations in infants with transposition of the great arteries

Cognitive Neuroscience and Neuropsychiatry Section, Institute of Child Health, 30 Guildford Street, London, UK Background Transposition of the great arteries (TGA) is congenital heart defect which is associated with a risk of systemic hypoxia/ischaemic (HI) brain injury in the neonatal period. Children and adolescents with corrected TGA have been reported to show motor coordination and cognitive deficits, and increased incidence of psychiatric diagnoses in follow-up. Methods We examined the ontogeny of cognitive and motor coordination deficits in relation to structural magnetic resonance Imaging (MRI) evidence of the integrity of the hippocampus and basal ganglia, by conducting a longitudinal, prospective study of groups of infants treated for TGA and age-matched healthy controls (NC). All infants were free from any neurological diagnoses. Results Voxel-Based Morphometry (VBM) analysis indicated that infants with TGA have reduced grey-matter volume in the hippocampus relative to NC. This finding is consistent with previous reports that older children with TGA have reduced hippocampal volumes. Magnetic resonance spectroscopy (MRS) was also used for the assessment of focal brain pathology in the caudate and thalamus. No evidence of pathology was revealed in either structure. The Bayley Scales of Infant Development were used to assess cognitive, fine-motor, gross-motor, expressive language and receptive language skills at two time-points (age six months and 12 months). At six months of age, the TGA group was delayed relative to NC on the gross-motor scale only. At 12 months of age, the TGA group showed significant delays on the cognitive, expressive language and fine motor scales. Conclusion We conclude that infants with corrected TGA suffer HI damage to the hippocampus during the perinatal period which has significant consequences for subsequent development within the first year of life. These data provide insight into the emergence of cognitive and motor deficits in infants with TGA.