Results from neuroimaging studies have been mixed. Some neuroimaging studies have not found sex differences in cortical thickness (Nopoulos et al., 2000; O'Donnell, Noseworthy, Levine, & Dennis, 2005; Salat, 2004) after covarying for total brain volume, or they have found trends towards greater thickness in males (Salat, 2004). Others have found thicker cortex in females after taking differences in overall brain volume into account. Luders and colleagues measured cortical thickness in sixty healthy right handed adults (females aged 24.32 +- 4.35 years; males 25.45 +- 4.72 years), using a method in which spatially homologous regions of the cortex were aligned between individuals by matching patterns of cortical landmarks (Luders et al., 2006). They found that when total brain volume was covaried, the cortex was thicker in females across nearly the entire lateral surface of the brain. If unadjusted values were used, a similar but less widespread pattern of greater thickness in females was found, which was most pronounced in the left inferior and superior frontal gyri, and then to a lesser extent in the superior pre- and post-central regions and
