Distinct genetic influences on cortical surface area and cortical thickness.
Neuroimaging studies examining the effects of aging and neuropsychiatric disorders on the cerebral cortex have largely been based on measures of cortical volume. Given that cortical volume is a product of thickness and surface area, it is plausible that measures of volume capture at least 2 distinct sets of genetic influences. The present study aims to examine the genetic relationships between measures of cortical surface area and thickness. Participants were men in the Vietnam Era Twin Study of Aging (110 monozygotic pairs and 92 dizygotic pairs). Mean age was 55.8 years (range: 51-59). Bivariate twin analyses were utilized in order to estimate the heritability of cortical surface area and thickness, as well as their degree of genetic overlap. Total cortical surface area and average cortical thickness were both highly heritable (0.89 and 0.81, respectively) but were essentially unrelated genetically (genetic correlation = 0.08). This pattern was similar at the lobar and regional levels of analysis. These results demonstrate that cortical volume measures combine at least 2 distinct sources of genetic influences. We conclude that using volume in a genetically informative study, or as an endophenotype for a disorder, may confound the underlying genetic architecture of brain structure.
Panizzon
Matthew S
MS
Department of Psychiatry, University of California, San Diego, La Jolla, CA 92093, USA. mspanizz@ucsd.edu
Fennema-Notestine
Christine
C
Eyler
Lisa T
LT
Jernigan
Terry L
TL
Prom-Wormley
Elizabeth
E
Neale
Michael
M
Jacobson
Kristen
K
Lyons
Michael J
MJ
Grant
Michael D
MD
Franz
Carol E
CE
Xian
Hong
H
Tsuang
Ming
M
Fischl
Bruce
B
Seidman
Larry
L
Dale
Anders
A
Kremen
William S
WS
D002540:Cerebral Cortex / Q000033:anatomy & histology* / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009929:Organ Size / Q000235:genetics; D014427:Twins / Q000235:genetics*