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Gender differences in white matter microstructure.

Kanaan RA, Allin M, Picchioni M, Barker GJ, Daly E, Shergill SS, Woolley J, McGuire PK - PLoS ONE (2012)

Bottom Line: Men had higher fractional anisotropy (FA) in cerebellar white matter and in the left superior longitudinal fasciculus; women had higher FA in the corpus callosum, confirmed by ROI.The size of the differences was substantial--of the same order as that attributed to some pathology--suggesting gender may be a potentially significant confound in unbalanced clinical studies.The relatively increased superior longitudinal fasciculus and cerebellar FA in men may reflect their increased language lateralisation and enhanced motor development, respectively.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychological Medicine, King's College London, Institute of Psychiatry, London, United Kingdom. richard.kanaan@kcl.ac.uk

ABSTRACT

Background: Sexual dimorphism in human brain structure is well recognised, but little is known about gender differences in white matter microstructure. We used diffusion tensor imaging to explore differences in fractional anisotropy (FA), an index of microstructural integrity.

Methods: A whole brain analysis of 135 matched subjects (90 men and 45 women) using a 1.5 T scanner. A region of interest (ROI) analysis was used to confirm those results where proximity to CSF raised the possibility of partial-volume artefact.

Results: Men had higher fractional anisotropy (FA) in cerebellar white matter and in the left superior longitudinal fasciculus; women had higher FA in the corpus callosum, confirmed by ROI.

Discussion: The size of the differences was substantial--of the same order as that attributed to some pathology--suggesting gender may be a potentially significant confound in unbalanced clinical studies. There are several previous reports of difference in the corpus callosum, though they disagree on the direction of difference; our findings in the cerebellum and the superior longitudinal fasciculus have not previously been noted. The higher FA in women may reflect greater efficiency of a smaller corpus callosum. The relatively increased superior longitudinal fasciculus and cerebellar FA in men may reflect their increased language lateralisation and enhanced motor development, respectively.

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Areas of Gender Difference in Fractional Anisotropy.Red areas represent higher FA in women; Blue areas represent higher FA in men. Numbers Refer to the MNI Z-coordinate of the image below. The Left side of the brain is depicted on the Right side of the images.
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pone-0038272-g001: Areas of Gender Difference in Fractional Anisotropy.Red areas represent higher FA in women; Blue areas represent higher FA in men. Numbers Refer to the MNI Z-coordinate of the image below. The Left side of the brain is depicted on the Right side of the images.

Mentions: The primary analysis found men to have higher FA in the cerebellum, and an area at the anterior portion of the left superior longitudinal fasciculus; women to have higher FA in the corpus callosum (see table 2, figure 1). Repeating the analysis with age or handedness as a covariate did not change the significance of the clusters. Since the corpus callosum cluster was peri-ventricular, an ROI analysis was performed to exclude partial volume effect: this confirmed the higher corpus callosum FA in women (women: mean 0.762, standard deviation 0.055; men: mean 0.744, standard deviation 0.048; Mann Whitney U test, after Kolmogorov-Smirnov test for normality: pā€Š=ā€Š0.016).


Gender differences in white matter microstructure.

Kanaan RA, Allin M, Picchioni M, Barker GJ, Daly E, Shergill SS, Woolley J, McGuire PK - PLoS ONE (2012)

Areas of Gender Difference in Fractional Anisotropy.Red areas represent higher FA in women; Blue areas represent higher FA in men. Numbers Refer to the MNI Z-coordinate of the image below. The Left side of the brain is depicted on the Right side of the images.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3368921&req=5

pone-0038272-g001: Areas of Gender Difference in Fractional Anisotropy.Red areas represent higher FA in women; Blue areas represent higher FA in men. Numbers Refer to the MNI Z-coordinate of the image below. The Left side of the brain is depicted on the Right side of the images.
Mentions: The primary analysis found men to have higher FA in the cerebellum, and an area at the anterior portion of the left superior longitudinal fasciculus; women to have higher FA in the corpus callosum (see table 2, figure 1). Repeating the analysis with age or handedness as a covariate did not change the significance of the clusters. Since the corpus callosum cluster was peri-ventricular, an ROI analysis was performed to exclude partial volume effect: this confirmed the higher corpus callosum FA in women (women: mean 0.762, standard deviation 0.055; men: mean 0.744, standard deviation 0.048; Mann Whitney U test, after Kolmogorov-Smirnov test for normality: pā€Š=ā€Š0.016).

Bottom Line: Men had higher fractional anisotropy (FA) in cerebellar white matter and in the left superior longitudinal fasciculus; women had higher FA in the corpus callosum, confirmed by ROI.The size of the differences was substantial--of the same order as that attributed to some pathology--suggesting gender may be a potentially significant confound in unbalanced clinical studies.The relatively increased superior longitudinal fasciculus and cerebellar FA in men may reflect their increased language lateralisation and enhanced motor development, respectively.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychological Medicine, King's College London, Institute of Psychiatry, London, United Kingdom. richard.kanaan@kcl.ac.uk

ABSTRACT

Background: Sexual dimorphism in human brain structure is well recognised, but little is known about gender differences in white matter microstructure. We used diffusion tensor imaging to explore differences in fractional anisotropy (FA), an index of microstructural integrity.

Methods: A whole brain analysis of 135 matched subjects (90 men and 45 women) using a 1.5 T scanner. A region of interest (ROI) analysis was used to confirm those results where proximity to CSF raised the possibility of partial-volume artefact.

Results: Men had higher fractional anisotropy (FA) in cerebellar white matter and in the left superior longitudinal fasciculus; women had higher FA in the corpus callosum, confirmed by ROI.

Discussion: The size of the differences was substantial--of the same order as that attributed to some pathology--suggesting gender may be a potentially significant confound in unbalanced clinical studies. There are several previous reports of difference in the corpus callosum, though they disagree on the direction of difference; our findings in the cerebellum and the superior longitudinal fasciculus have not previously been noted. The higher FA in women may reflect greater efficiency of a smaller corpus callosum. The relatively increased superior longitudinal fasciculus and cerebellar FA in men may reflect their increased language lateralisation and enhanced motor development, respectively.

Show MeSH