Childhood sexual abuse is associated with reduced gray matter volume in visual cortex of young women

Abstract

Background: Childhood sexual abuse (CSA) has been associated with alterations in brain morphology using region of interest analyses that have focused on stress-sensitive target regions. This study was designed to ascertain the effects on gray matter volume (GMV) of exposure to CSA in healthy young adult college students selected based on exposure history regardless of psychiatric outcome. Voxel-based morphometry (VBM) provided unbiased delineation of the most significantly affected brain regions.

Methods: High-resolution T1-weighted magnetic resonance imaging (MRI) datasets were obtained for 23 unmedicated female subjects with CSA and 14 healthy female control subjects of equivalent age and socioeconomic status with no history of trauma. Cortical surface-based analysis (FreeSurfer) was performed to verify VBM results.

Results: Gray matter volume was reduced by 12.6% and 18.1% in right and left primary visual (V1) and visual association cortices of abused subjects. This reduction was directly related to duration of CSA before age 12. Gray matter volume of left and right V1 correlated with measure of visual memory (r = .353, p = .032 and r = .448, p = .005). Cortical surface-based analysis indicated that GMV of abused subjects was reduced in the left fusiform (p = .004), left middle occipital (p = .04), and right lingual (p = .002) gyri.

Conclusions: Early visual experience exerts a strong influence on the developing mammalian visual cortex. Present findings indicate that exposure to CSA may also affect the development of this region and are apparent even in a population of subjects who are sufficiently healthy to matriculate.

Figure 1

Portrayal of the locations of significant differences between abused subjects and controls in regional gray matter volume as revealed by voxel-based morphometry. Significantly lower gray-matter densities in abused subjects were measured in the left and right visual cortex. Color scale: 0–5 represents t-values.

Figure 2

Scatter plot portraying the relation between gray matter volume and visual memory on the Memory Assessment Scale at the cluster location of maximal correlation in right lingual gyrus (x= 12, y= −85, z= 17). Linear regression for all subjects, and for controls only, shown as solid black line and dashed blue line. Regression in CSA subjects (red dotted line) shown excluding anomalous data point (r = 0.484). There was no significant correlation between visual memory and right V1 GMV in CSA subjects with all points included (r = 0.061).

Figure 3

Mean (±SE) gray matter volume (GMV) in the visual cortex acquired by cortical surface-based analysis showing differences between healthy controls and subjects with repeated exposure to childhood sexual abuse. *, P < 0.05; **, P < 0.01; and ***, P < 0.005. ^aSignificant difference between two groups in the left visual cortex (abused 34838±627 versus vs. controls 37886±838; F = 8.3, df = 1,34, P = 0.007). ^bSignificant difference between two groups in the right visual cortex (35887±518 vs. 37773±693; F = 4.7, df = 1,34, P = 0.038). ^cSignificant difference between two groups in the left middle occipital gyrus (8347±243 vs. 9219±325; F = 4.5, df = 1,34, P = 0.041). ^dSignificant difference between two groups in the left fusiform gyrus (4285±181 vs. 5226±242; F = 9.5, df = 1,34, P = 0.004). ^eSignificant difference between two groups in the right lingual gyrus (10289±179 vs. 11300±239; F = 11.2, df = 1,34, P = 0.002).