title: Magnetic susceptibility of brain iron is associated with childhood spatial IQ.
abstract: Iron is an essential micronutrient for healthy brain function and development. Because of the importance of iron in the brain, iron deficiency results in widespread and lasting effects on behavior and cognition. We measured iron in the basal ganglia of young children using a novel MRI method, quantitative susceptibility mapping, and examined the association of brain iron with age and cognitive performance. Participants were a community sample of 39 young children recruited from pediatric primary care who were participating in a 5-year longitudinal study of child brain development and anxiety disorders. The children were ages 7 to 11years old (mean age: 9.5years old) at the time of the quantitative susceptibility mapping scan. The differential abilities scale was administered when the children were 6years old to provide a measure of general intelligence and verbal (receptive and expressive), non-verbal, and spatial performance. Magnetic susceptibility values, which are linearly related to iron concentration in iron-rich areas, were extracted from regions of interest within iron-rich deep gray matter nuclei from the basal ganglia, including the caudate, putamen, substantia nigra, globus pallidus, and thalamus. Controlling for scan age, there was a significant positive association between iron in the basal ganglia and spatial IQ, with this effect being driven by iron in the right caudate We also replicated previous findings of a significant positive association between iron in the bilateral basal ganglia and age. Our finding of a positive association between spatial IQ and mean iron in the basal ganglia, and in the caudate specifically, suggests that iron content in specific regions of the iron-rich deep nuclei of the basal ganglia influences spatial intelligence. This provides a potential neurobiological mechanism linking deficits in spatial abilities reported in children who were severely iron deficient as infants to decreased iron within the caudate.
authors.affiliation: Department of Psychiatry and Behavioral Sciences, Duke University School of Medicine, Durham, NC, USA. Electronic address: kimberly.carpenter@dm.duke.edu.
authors.forename: Kimberly L H
authors.initials: KLH
authors.lastname: Carpenter
authors.affiliation: Research Imaging Institute, University of Texas Health Science Center, San Antonio, TX, USA; Department of Ophthalmology, University of Texas Health Science Center, San Antonio, TX, USA; Brain Imaging and Analysis Center, Duke University School of Medicine, Durham, NC, USA.
authors.forename: Wei
authors.initials: W
authors.lastname: Li
authors.affiliation: Brain Imaging and Analysis Center, Duke University School of Medicine, Durham, NC, USA.
authors.forename: Hongjiang
authors.initials: H
authors.lastname: Wei
authors.affiliation: Brain Imaging and Analysis Center, Duke University School of Medicine, Durham, NC, USA; GE Healthcare, Beijing, China.
authors.forename: Bing
authors.initials: B
authors.lastname: Wu
authors.affiliation: Brain Imaging and Analysis Center, Duke University School of Medicine, Durham, NC, USA; Department of Biomedical Engineering, Tsinghua University, Beijing, China.
authors.forename: Xue
authors.initials: X
authors.lastname: Xiao
authors.affiliation: Brain Imaging and Analysis Center, Duke University School of Medicine, Durham, NC, USA; Department of Radiology, Duke University School of Medicine, Durham, NC, USA.
authors.forename: Chunlei
authors.initials: C
authors.lastname: Liu
authors.affiliation: Program in Neurodevelopmental Disabilities, Division of Pediatric Neurology, Department of Pediatrics, Duke University School of Medicine, Durham, NC, USA.
authors.forename: Gordon
authors.initials: G
authors.lastname: Worley
authors.affiliation: Department of Psychiatry and Behavioral Sciences, Duke University School of Medicine, Durham, NC, USA.
authors.forename: Helen Link
authors.initials: HL
authors.lastname: Egger
mesh_terms: D001479:Basal Ganglia / Q000737:chemistry* / Q000000981:diagnostic imaging; D001921:Brain / Q000000981:diagnostic imaging; D001923:Brain Chemistry; D001931:Brain Mapping / Q000379:methods*; D002648:Child; D005260:Female; D006801:Humans; D007360:Intelligence; D007361:Intelligence Tests; D007501:Iron / Q000032:analysis*; D060328:Magnetic Phenomena; D008279:Magnetic Resonance Imaging; D008297:Male; D009483:Neuropsychological Tests
chemical_list: D007501:Iron
keywords: Brain iron; Caudate; Quantitative susceptibility mapping; Spatial intelligence