MRI study on morphological changes of adult cerebral cortex in aging

Objective To explore the regional and lateral differences of adult cerebral cortex volume, thickness and surface area during normal aging by MRI. Methods The prospective study was conducted. From September 2017 to January 2018, 109 healthy adult volunteers of right-handed Han nationality were recruited, including 56 males and 53 females, average age (53.13±15.61) years (aged 18-85 years). The original data of 3.0 T MRI were obtained and analyzed with FreeSurfer software to obtain the interesting areas of left and right hemispheres and lobes. The specific values of the volume, including thickness and surface area of the regional cerebral cortex were studied to explore the correlation with age, the regional and lateral differences of cerebral cortex aging. Results Linear regression analysis showed age-related decreases in global cortical volume, thickness and surface area (P<0.01). The largest age-related decreases in cortical volume were in the middle frontal gyrus, inferior frontal gyrus, inferior parietal angular gyrus, lingual gyrus, middle temporal gyrus and parahippocampal gyrus(the largest was -0.653% per year, P<0.01). The areas with the greatest decrease in cortical thickness were the middle frontal gyrus, the frontal gyrus of outer orbit, the inferior parietal angular gyrus, the superior temporal gyrus, the temporal pole, the parahippocampal gyrus and the posterior cingulate gyrus(the largest was -0.009 mm per year, P<0.01). The areas with the greatest decrease in cortical surface area were mainly in the middle frontal gyrus, the infra-frontal gyrus, the lingual gyrus, the inferior temporal gyrus and the parahippocampal gyrus (the largest was -0.40% per year, P<0.01). The asymmetric regions of cortical volume-age effect in the left and right hemispheres were superior frontal gyrus, inferior frontal gyrus and triangle, middle orbital frontal gyrus, frontal pole, inferior parietal marginal angular gyrus, superior marginal gyrus, fusiform gyrus, temporal pole, parahippocampal gyrus, anterior cingulate gyrus and entorhinal cortex(P<0.05). The asymmetric regions of age effect of cortical thickness were superior frontal gyrus, inferior frontal gyrus, middle orbital frontal gyrus, cuneate lobe, inferior temporal gyrus, temporal pole, anterior cingulate gyrus and posterior cingulate gyrus (P<0.05). The asymmetric regions of age effect of cortical surface area were superior frontal gyrus, middle frontal gyrus, inferior frontal gyrus, trigone, frontal pole, inferior parietal angular gyrus, superior marginal gyrus, fusiform gyrus, temporal pole, parahippocampal gyrus, anterior cingulate gyrus, posterior cingulate gyrus and entorhinal cortex (P<0.05). Conclusions In normal aging process of human brain, the volume, thickness and surface area of cerebral cortex show linear negative correlations with age. Aging has different effects in cortical regions. The age effect of partial gyri is lateralized. Three morphological indexes of cortical volume, thickness and surface area are interrelated. Key words: Cerebral cortex; Magnetic resonance imaging; Brain aging; Cortical volume; Cortical thickness; Cortical surface area; Region of interest