Choi J, Jeong B, Rohan ML, Polcari AM, Teicher MH. Preliminary evidence for white matter tract abnormalities in young adults exposed to parental verbal abuse. Biol Psychiatry. 2009 Feb 1;65(3):227-34.
We have just published findings from my laboratory that are beginning to illuminate the neurobiological effects of exposure to parental verbal abuse. We had previously shown that exposure to high levels of parental verbal abuse had the same impact (based on symptom ratings) as witnessing domestic violence and extrafamilial sexual abuse. It had somewhat more impact than exposure to parental physical abuse, but less impact than familial sexual abuse. Hence, it appears to be a potent form of childhood adversity.
White Matter Tract Abnormalities in Young Adults Exposed to Parental Verbal Abuse
In this study we used a new MRI technique called diffusion tensor imaging (DTI) to ascertain whether exposure to a high level of parental verbal abuse (PVA) was associated with abnormalities in brain white matter (WM) tract integrity. The brain consists of regions of gray matter that contains the cell bodies and dendritic branches of neurons, and white matter, which are the myelinated axonal fiber tracts providing communication between neurons in different gray matter regions. We screen 1271 healthy young adults for exposure to childhood adversity, and collected DTI (Siemens 3.0 T Trio Scanner) on 16 unmedicated subjects with a history of high-level exposure to PVA but no other form of maltreatment (4M/12F, mean age 21.9±2.4 yrs), and 16 healthy controls (5M/11F, 21.0±1.6 yrs). Group differences in fractional anisotropy (FA), covaried by parental education and income, were evaluated using tract-based spatial statistics (TBSS), and correlated with symptom ratings and verbal IQ. FA is an index of the integrity of the fiber pathway. Reduced FA may indicate a reduction in myelin, number of axons, or diameter of axons.
Three WM tracts had significantly reduced FA: (1) arcuate fasciculus in left superior temporal gyrus, (2) cingulum bundle in the fusiform gyrus by the posterior tail of the left hippocampus, and (3) the left body of fornix. FA values were strongly associated with the maximal PVA scores (r=-0.806, P<10-7; r=-0.658, P<.0001; r=-0.584, P<.0001, respectively).
Figure 1. Three white matter tract regions (shown in red) that differed significantly in fractional anisotropy (FA) between subjects with history of exposure to high levels of parental verbal aggression and healthy controls. Region 1 contained fibers from arcuate fasciculus. Region 2 contained fibers from the cingulum bundle near the tail of the hippocampus. Region 3 is part of the left fornix (hippocampal efferents). Green shows the mean FA skeleton and background image is in MNI 152. Tractography from representative subjects show tracts passing through the region identified by TBSS.
FA in region 1 correlated with verbal IQ (r=0.405, P<.03). The arcuate fasciculus is the fiber pathway that connects Wenicke’s area in the temporal lobe to Broca’s area in the frontal lobe. It plays an important role in verbal comprehension and communication. FA in region 2 was inversely associated with ratings of depression (r=–0.442), dissociation (r=–0.447), and limbic irritability(r=–0.483). The cingulum bundle is the most prominent tract of the limbic lobe, and connects the limbic lobe with the neocortex, particularly the cingulate gyrus. FA in region 3 was inversely correlated with anxiety (r=–0.36) and somatization (r=–0.371). The fornix is a pathway that interconnects hippocampus with the septal area and mammillary bodies, and is known to play a role in anxiety and memory. Interestingly, the hippocampus receives serotonin fibers from the midbrain raphe via two pathways: the cingulum bundle (which predominantly innervates dorsal hippocampus), and the fornix (which innervates all portions). Hence, two of the fiber tracts with segments of reduced FA in PVA subjects, provide pathways for serotonin fibers to innervate the hippocampus.
This study provides the first evidence that high levels of parental verbal aggression may be a form of abuse or adversity that alters trajectories of brain development. It supports our previous hypothesis that different forms of childhood maltreatment will exert some comparable an array of consistent neurobiological effects (particularly on limbic regions or connection) as they are all stressors. However, different forms of abuse will also have some unique effects based on sensory systems activated that convey the aversive stimulus to specific parts of the brain that process and interpret the information.
This work was supported, in part, by National Institute of Mental Health RO1 grants MH53636 and MH-66222, and National Institute of Drug Abuse RO1 grants DA-016934 and DA-017846 to MHT.