with younger females having larger hippocampi. In a whole brain regression analysis, testosterone was positively associated with increased GM density in right sided diencephalic structures in males, and negatively correlated with parietal GM volume in males. Estradiol levels were positively correlated with greater GM density in the uncus and parahippocampal gyri in girls only. Although this study did not look at effects of sex steroids and pubertal stages separately from effects of chronologic age, the sex-specific effects of testosterone and estrogen are consistent with findings that sex steroids continue to have organizational effects on brain structure during puberty. For more discussion of the effects of pubertal timing on behavior in adolescents, please see the paper by Dahl and Forbes, this issue.
