title: Genetic and environmental contributions to neonatal brain structure: A twin study.
abstract: Twin studies have found that global brain volumes, including total intracranial volume (ICV), total gray matter, and total white matter volumes are highly heritable in adults and older children. Very little is known about genetic and environmental contributions to brain structure in very young children and whether these contributions change over the course of development. We performed structural imaging on a 3T MR scanner of 217 neonatal twins, 41 same-sex monozygotic, 50 same-sex dizygotic pairs, and 35 "single" twins-neonates with brain scans unavailable for their co-twins. Tissue segmentation and parcellation was performed, and structural equation modeling was used to estimate additive genetic, common environmental, and unique environmental effects on brain structure. Heritability of ICV (0.73) and total white matter volume (0.85) was high and similar to that described in older children and adults; the heritability of total gray matter (0.56) was somewhat lower. Heritability of lateral ventricle volume was high (0.71), whereas the heritability of cerebellar volume was low (0.17). Comparison with previous twin studies in older children and adults reveal that three general patterns of how heritability can change during postnatal brain development: (1) for global white matter volumes, heritability is comparable to reported heritability in adults, (2) for global gray matter volume and cerebellar volume, heritability increases with age, and (3) for lateral ventricle volume, heritability decreases with age. More detailed studies of the changes in the relative genetic and environmental effects on brain structure throughout early childhood development are needed.
authors.affiliation: UNC Schizophrenia Research Center, Department of Psychiatry, University of North Carolina, Chapel Hill, USA. jgilmore@med.unc.edu
authors.forename: John H
authors.initials: JH
authors.lastname: Gilmore
authors.forename: James Eric
authors.initials: JE
authors.lastname: Schmitt
authors.forename: Rebecca C
authors.initials: RC
authors.lastname: Knickmeyer
authors.forename: Jeffrey K
authors.initials: JK
authors.lastname: Smith
authors.forename: Weili
authors.initials: W
authors.lastname: Lin
authors.forename: Martin
authors.initials: M
authors.lastname: Styner
authors.forename: Guido
authors.initials: G
authors.lastname: Gerig
authors.forename: Michael C
authors.initials: MC
authors.lastname: Neale
mesh_terms: D001921:Brain / Q000033:anatomy & histology* / Q000502:physiology*; D001931:Brain Mapping; D004777:Environment; D005260:Female; D005823:Genetics; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D007223:Infant; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male