Sexual Dimorphism in Surface Anatomical Parameters of Human Cerebral Cortex in Different Lebes in Normal and Neurodegenerative Subjects: a Stereological and Macroscopical Study

Purpose: This study sought to determine sex differences in surface anatomical parameters (thickness and surface areas) of human cerebral cortex in different lobes of the left hemisphere in normal right-handed subjects and right-handed subjects suffering from Alzheimer and Parkinson's diseases. Materials and Methods: This cross-sectional descriptive study was performed on 72 normal human brains (38 males, 34 females); 11 brains suffered from Alzheimer (4 males, 7 females), and 13 brains suffered from Parkinson's disease (9 males, 4 females). The age of the males and females in each group was similar.The right hemisphere of each brain was used for neuropathological diagnosis, and the left one was used for morphometrical analysis. The stmation of thickness and surface areas in the cerebral cortex of different lobes of the left hemisphere was performed on photographs of 5mm serial coronal sections of this hemisphere with a linear grid based on unbiased sterelogical method. The results were analyzed by t-student and non-parametrical Mann- Whitney statistical tests. Results: The thickness of the left parietal cortex was significantly smaller in healthy right-handed women than in men (p=0.02). The thickness of cortex in other lobes of the left hemisphere showed no significant sexual difference in healthy right-handed subjects; however, there was a tendency (0.05<p<0.1) for a smaller thickness in women rather than in men. The outer surface area of the left parietal and temporal cortices was similar between two sexes in healthy right-handed subjects, whereas the outer surface area of the left frontal cortex was smaller in women (p=0.02), and there was also a tendency (0.05<p<0.1) for a smaller outer surface area in the left occipital cortex in women. The inner and mean cortical surface areas in different lobes of the left hemisphere were almost similar between two sexes in healthy right-handed subjects. There was a tendency (0.05<p<0.1) for smaller inner and mean surface areas of the left occipital cortex in women. The surface anatomical parameters (thickness and surface areas) of the cortex in different lobes of the left hemisphere were similar between males and females in right-handed subjects suffering from Alzheimer and Parkinson's diseases. Conclusion: It is concluded that the thickness of the left parietal cortex and the outer surface area of the left frontal cortex is smaller in healthy right-handed women than in men. These normal sexual differences in surface anatomical parameters of the cerebral cortex disappear in alzheimer and Parkirison's diseases. Changes in the normal pattern of cortical sexual dimorphism in neurodegenerative diseases can be due to more degeneration of the cerebral cortex in men.