Sexual Dimorphism and Age-Related Variations of Corpus Callosum Using Magnetic Resonance Imaging

Introduction: Despite technological advances and numerous published investigations, sexual dimorphism of Corpus Callosum (CC) remains a matter of ongoing controversy. In the present study on neurologically healthy Iranian adults, we investigated the possible gender- and agerelated variations in anthropometric callosal measurements. Methods: Our sample comprised 35 male and 35 female subjects with the mean (SD) age of 42.8 (14.7) and 44.7 (15) years, respectively, who referred to Partow Magnetic Resonance Imaging (MRI) center in North of Iran for headache work-up. Individuals with known neurologic disorders, history of head trauma, left handed subjects, and those younger than 20 and older than 80 years old were excluded. We measured callosal and brain dimensions on the midsagittal section and analyzed the data using Independent sample t test, analysis of variance, analysis of covariance, Pearson correlation coefficient, and linear regression. Results: The unadjusted dimensions were larger in male participants compared to female ones. Corpus callosum area on the midsagittal plane, the longitudinal brain and callosal measurements and dimensions related to the width of CC were significantly larger in males than females (P<0.05). Overall, the longitudinal dimensions of CC were larger in the elderly, while the younger subjects have significantly thicker callosal dimensions. The observed gender-related differences lost their statistical significance after adjusting for longitudinal brain dimensions. Conclusion: We found apparently larger callosal dimensions in the male participants, which could be an artifact caused by the significantly larger male brain dimensions. Our investigations on the less studied racial groups also provide further evidence regarding the confounding effect of brain volume on the observed sexual dimorphism of CC.