The effect of sex and age on cortical grey and white matter volumes of frontal lobe

Grey matter (GM) of the frontal lobe carries out its complex function such as muscle control, speech, decision making, and self-control; while the white matter (WM) of frontal lobe is a major contributor to human brain enlargement and higher structural connectivity. This study was conducted to assess the effect of sex and age on grey and white matter volumes (GMV and WMV) of the frontal lobe and its gyri in healthy young adult Sudanese. The present study included 139 healthy Sudanese subjects (80 males and 59 females). Participant’s ages were ranging between 20-40 years. T1-weighted MR brain images with thickness 1mm were obtained. MR images of the subjects were analyzed using the automatic segmentation software (BrainSuite). GMV and WMV of frontal lobe and its gyri were estimated using the output data of the process of software. Males had greater GMV and WMV of the frontal lobes (251.18±31.80cm3 and 143.48±22.92cm3, respectively) and most of frontal lobe gyri (P<0.05). Change with age in GMV has been reported in the frontal lobes, superior frontal gyrus, pars orbitalis, orbitofrontal, and cingulate gyrus (P<0.05). Change with age in WM volumes has been found in the cingulate, precentral, and paracentral gyri (P<0.05). Sex has prominent effect on GMV and WMV of the frontal lobes and most of frontal lobe gyri, thus sex is a major contributor to GMV and WMV differences between individuals. Age effect GMV and WMV of most frontal lobe gyri, these findings confirm the continuation of maturation of frontal lobe until fourth decade. Assessing effect of sex and age on GM and WM in healthy adult has major importance to distinguish the normal brain from diseased.