Citation

Posthuma D, Baaré WF, Hulshoff Pol HE, Kahn RS, Boomsma DI, De Geus EJ. Twin Res. 2003; 6(2): 131-139.

Affiliation

Department of Biological Psychology, Vrije Universiteit, van der Boechorststraat 1, 1081 BT Amsterdam, the Netherlands. danielle@psy.vu.nl

Copyright

(Copyright © 2003, Australian Academic Press)

DOI

10.1375/136905203321536254

PMID

12723999

Abstract

We recently showed that the correlation of gray and white matter volume with full scale IQ and the Working Memory dimension are completely mediated by common genetic factors (Posthuma et al., 2002). Here we examine whether the other WAIS III dimensions (Verbal Comprehension, Perceptual Organization, Processing Speed) are also related to gray and white matter volume, and whether any of the dimensions are related to cerebellar volume. Two overlapping samples provided 135 subjects from 60 extended twin families for whom both MRI scans and WAIS III data were available. All three brain volumes are related to Working Memory capacity (r = 0.27). This phenotypic correlation is completely due to a common underlying genetic factor. Processing Speed was genetically related to white matter volume (r(g) = 0.39). Perceptual Organization was both genetically (r(g) = 0.39) and environmentally (r(e) = -0.71) related to cerebellar volume. Verbal Comprehension was not related to any of the three brain volumes. It is concluded that brain volumes are genetically related to intelligence which suggests that genes that influence brain volume may also be important for intelligence. It is also noted however, that the direction of causation (i.e., do genes influence brain volume which in turn influences intelligence, or alternatively, do genes influence intelligence which in turn influences brain volume), or the presence or absence of pleiotropy has not been resolved yet.

Language: en