Few MRS studies evaluated brain development in relation to genetic factors. Multiple studies showed that brain metabolites change rapidly early in life and then more subtly and linearly after puberty (Kreis et al. 1993; Pouwels et al. 1999; Kadota et al. 2001; G. Goldstein et al. 2009). To date, only one MRS study evaluated sexual dimorphism across the lifespan (4–88 years), using the NAA/Cho ratio in the centrum semiovale (Kadota et al., 2001). Boys exhibited a steeper age-related increase in NAA/Cho in the white matter than girls, and the age-dependent trajectory of the NAA/Cho peaked 1 to 3 years earlier in boys than in girls (Kadota et al. 2001). Cerebral laterality in WM NAA/Cho ratios also differed by sex: greater NAA/Cho ratios were found in the right compared to the left WM in boys, but not in girls. In adults, age-related changes in brain metabolites were reported but considerable heterogeneity of metabolite concentrations across studies were found (Kadota et al. 2001; Baker et al. 2008; Maudsley et al. 2009; Chang et al. 1996). Note also that metabolite ratios are difficult
