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Distinct genetic influences on cortical surface area and cortical thickness
Matthew S Panizzon1, Christine Fennema-Notestine, Lisa T Eyler
1Department of Psychiatry, University of California, San Diego, La Jolla, CA 92093, USA. mspanizz@ucsd.edu
Cerebral Cortex (New York, N.Y. : 1991)
|March 21, 2009
Summary
Cortical volume combines distinct genetic influences on brain thickness and surface area. These brain measures are highly heritable but genetically independent, suggesting volume studies may confound genetic architecture.
Area of Science:
- Neurogenetics
- Brain Imaging
- Aging Research
Background:
- Neuroimaging studies often use cortical volume to assess aging and neuropsychiatric disorders.
- Cortical volume is a composite measure of cortical thickness and surface area.
- Distinct genetic influences may underlie thickness and surface area.
Purpose of the Study:
- To investigate the genetic relationships between cortical surface area and thickness.
- To determine the heritability and genetic overlap of these two cortical measures.
Main Methods:
- Utilized bivariate twin analyses in the Vietnam Era Twin Study of Aging.
- Included 110 monozygotic and 92 dizygotic twin pairs (mean age 55.8 years).
- Estimated heritability and genetic correlations for total and regional cortical measures.
Main Results:
- Both total cortical surface area (heritability=0.89) and average cortical thickness (heritability=0.81) were highly heritable.
- Cortical surface area and thickness showed minimal genetic overlap (genetic correlation=0.08).
- This pattern of low genetic correlation was consistent across lobar and regional analyses.
Conclusions:
- Cortical volume measures integrate at least two independent genetic influences.
- Using cortical volume in genetic studies or as an endophenotype may obscure the true genetic architecture of brain structure.
- Future research should differentiate between genetic effects on cortical thickness and surface area.
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