Brain structure mediates the association between height and cognitive ability

Abstract

Height and general cognitive ability are positively associated, but the underlying mechanisms of this relationship are not well understood. Both height and general cognitive ability are positively associated with brain size. Still, the neural substrate of the height-cognitive ability association is unclear. We used a sample of 515 middle-aged male twins with structural magnetic resonance imaging data to investigate whether the association between height and cognitive ability is mediated by cortical size. In addition to cortical volume, we used genetically, ontogenetically and phylogenetically distinct cortical metrics of total cortical surface area and mean cortical thickness. Height was positively associated with general cognitive ability and total cortical volume and cortical surface area, but not with mean cortical thickness. Mediation models indicated that the wellreplicated height-general cognitive ability association is accounted for by individual differences in total cortical volume and cortical surface area (highly heritable metrics related to global brain size), and that the genetic association between cortical surface area and general cognitive ability underlies the phenotypic height-general cognitive ability relationship.

Weak correlations between body height and several brain metrics in healthy elderly subjects

“…The goal of this paper was to examine the relationship between body height and brain anatomical measures in a relatively large group of healthy older subjects. This question has recently come back into focus because several studies have reported a moderate body height to brain size relationship in preterm children (Sammallahti et al., ), in the context of ageing (Russ et al., ) and in large samples of mostly younger subjects (Posthuma et al., ; Vuoksimaa et al., ). Furthermore, this relationship has been associated with cognitive ability, in a way that brain size mediates the association between body height and cognitive ability (Vuoksimaa et al., ).…”

“…More specifically, our hypothesis was that intracranial volume would be most strongly related to body height. Owing to the fact that cortical surface area and cortical volume (Luders, Narr, Thompson, & Toga, ; Vuoksimaa et al., ) is most strongly related to general cognitive ability, we hypothesize that cortical surface area is less stable and will thus only be weakly related to body height.…”

“…There are only a few published MRI studies examining brain size and body height relationships. These studies also report heterogeneous results (Heymsfield et al., ; Koh et al., ; Nopoulos, Flaum, O'Leary, & Andreasen, ; Peters et al., ; Raz et al., ; Taki et al., ; Vuoksimaa et al., ; Wickett, Vernon, & Lee, ; Willerman, Schultz, Neal Rutledge, & Bigler, ). The strongest correlation has been reported by Koh et al.…”

“…The relationship between body height and brain size has recently received renewed interest, mainly due to the uncovered positive correlation between general cognitive ability (GCA) and body height (Adams et al., ; Keller et al., ; Marioni et al., ; Silventoinen, Iacono, Krueger, & McGue, ; Taki et al., ; Vuoksimaa et al., ). This association has been reported for preterm infants (Sammallahti et al., ), in the context of ageing (Russ, Kivimäki, Starr, Stamatakis, & Batty, ) and for a large sample spanning a wide age range (Vuoksimaa et al., ). Moreover, the study by Vuoksimaa et al.…”

“…Most of these studies have used total cortical volume or brain volume as a brain measure. Only one study (Vuoksimaa et al., ) has simultaneously used total cortical volume and cortical surface area and uncovered moderate brain size and body height relationships (cortical surface area: r = .238; cortical volume: r = .235). To the best of our knowledge, there is no published study available which has used a greater variety of brain measures (e.g., cortical thickness, cortical surface area, intracranial volume, subcortical volume, normal‐appearing cerebral white matter, cerebellum grey matter and cerebellum white matter) to shed light on the differential associations with body height.…”