title: The Genetic Association Between Neocortical Volume and General Cognitive Ability Is Driven by Global Surface Area Rather Than Thickness.
abstract: Total gray matter volume is associated with general cognitive ability (GCA), an association mediated by genetic factors. It is expectable that total neocortical volume should be similarly associated with GCA. Neocortical volume is the product of thickness and surface area, but global thickness and surface area are unrelated phenotypically and genetically in humans. The nature of the genetic association between GCA and either of these 2 cortical dimensions has not been examined. Humans possess greater cognitive capacity than other species, and surface area increases appear to be the primary driver of the increased size of the human cortex. Thus, we expected neocortical surface area to be more strongly associated with cognition than thickness. Using multivariate genetic analysis in 515 middle-aged twins, we demonstrated that both the phenotypic and genetic associations between neocortical volume and GCA are driven primarily by surface area rather than thickness. Results were generally similar for each of 4 specific cognitive abilities that comprised the GCA measure. Our results suggest that emphasis on neocortical surface area, rather than thickness, could be more fruitful for elucidating neocortical-GCA associations and identifying specific genes underlying those associations.
authors.affiliation: Department of Psychiatry Center for Behavioral Genomics Twin Research Laboratory Department of Public Health, University of Helsinki, Helsinki, Finland.
authors.forename: Eero
authors.initials: E
authors.lastname: Vuoksimaa
authors.affiliation: Department of Psychiatry Center for Behavioral Genomics Twin Research Laboratory.
authors.forename: Matthew S
authors.initials: MS
authors.lastname: Panizzon
authors.affiliation: Department of Psychiatry Center for Behavioral Genomics Twin Research Laboratory.
authors.forename: Chi-Hua
authors.initials: CH
authors.lastname: Chen
authors.affiliation: Department of Psychiatry Center for Behavioral Genomics Twin Research Laboratory.
authors.forename: Mark
authors.initials: M
authors.lastname: Fiecas
authors.affiliation: Department of Psychiatry Mental Illness Research Education and Clinical Center, VA San Diego Healthcare System, San Diego, CA, USA.
authors.forename: Lisa T
authors.initials: LT
authors.lastname: Eyler
authors.affiliation: Department of Psychiatry Department of Radiology and.
authors.forename: Christine
authors.initials: C
authors.lastname: Fennema-Notestine
authors.affiliation: Department of Radiology and.
authors.forename: Donald J
authors.initials: DJ
authors.lastname: Hagler
authors.affiliation: Department of Radiology, Massachusetts General Hospital, Boston, MA, USA Harvard Medical School, Boston, MA, USA Computer Science and AI Lab, Massachusetts Institute of Technology, Cambridge, MA, USA.
authors.forename: Bruce
authors.initials: B
authors.lastname: Fischl
authors.affiliation: Department of Psychiatry Center for Behavioral Genomics Twin Research Laboratory.
authors.forename: Carol E
authors.initials: CE
authors.lastname: Franz
authors.affiliation: Department of Psychiatry Center of Excellence for Stress and Mental Health, VA San Diego Healthcare System, La Jolla, CA, USA.
authors.forename: Amy
authors.initials: A
authors.lastname: Jak
authors.affiliation: Department of Psychology, Boston University, Boston, MA, USA.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Lyons
authors.affiliation: Virginia Institute for Psychiatric and Behavioral Genetics, Virginia Commonwealth University School of Medicine, Richmond, VA, USA.
authors.forename: Michael C
authors.initials: MC
authors.lastname: Neale
authors.affiliation: Department of Psychiatry Department of Radiology and.
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Rinker
authors.affiliation: Department of Psychiatry.
authors.forename: Wesley K
authors.initials: WK
authors.lastname: Thompson
authors.affiliation: Department of Psychiatry Center for Behavioral Genomics Twin Research Laboratory.
authors.forename: Ming T
authors.initials: MT
authors.lastname: Tsuang
authors.affiliation: Department of Radiology and Department of Neurosciences, University of California, San Diego, La Jolla, CA, USA.
authors.forename: Anders M
authors.initials: AM
authors.lastname: Dale
authors.affiliation: Department of Psychiatry Center for Behavioral Genomics Twin Research Laboratory Center of Excellence for Stress and Mental Health, VA San Diego Healthcare System, La Jolla, CA, USA.
authors.forename: William S
authors.initials: WS
authors.lastname: Kremen
mesh_terms: D000704:Analysis of Variance; D002540:Cerebral Cortex / Q000033:anatomy & histology*; D003071:Cognition; D056726:Genetic Association Studies; D006801:Humans; D007361:Intelligence Tests; D008279:Magnetic Resonance Imaging; D008875:Middle Aged; D008957:Models, Genetic; D015999:Multivariate Analysis; D009929:Organ Size; D014429:Twins, Dizygotic; D014430:Twins, Monozygotic
keywords: cognition; cortex; genetic correlation; heritability; twins