Functional and structural alterations of the anterior cingulate cortex (ACC), a key region for emotional and cognitive processing, are associated with borderline personality disorder (BPD). However, the interhemispheric structural connectivity between the left and right ACC and between other prefrontal regions in this condition is unknown. We acquired diffusion-tensor imaging data from 20 healthy women and 19 women with BPD and comorbid attention-deficit hyperactivity disorder (ADHD). Interhemispheric structural connectivity between both sides of the ACC, dorsolateral prefrontal cortices and medial orbitofrontal cortices was assessed by a novel probabilistic diffusion tensor-based fiber tracking method. In the BPD group as compared with healthy controls, we found decreased interhemispheric structural connectivity between both ACCs in fiber tracts that pass through the anterior corpus callosum and connect dorsal areas of the ACCs. Decreased interhemispheric structural connectivity between both ACCs may be a structural correlate of BPD.
The anterior cingulate cortex (ACC) is a key region for emotion regulation and impulse control (Davidson et al., 2000), both prominent symptoms of borderline personality disorder (BPD). BPD is associated with alterations of ACC structure and function in terms of reduced ACC volume (Tebartz van Elst et al., 2003, Hazlett et al., 2005, Minzenberg et al., 2008, Soloff et al., 2008 and Whittle et al., 2009), decreased activity during negative emotions and behavioral inhibition (Silbersweig et al., 2007), pain stimulation (Schmahl et al., 2006), response to fear stimuli (Minzenberg et al., 2007) and increased glutamate and N-acetylaspartate concentrations ( Rüsch et al., 2009). Previous structural imaging studies assessed the ACC as a separate region. However, recent findings point to impaired interhemispheric connectivity in BPD ( Williams et al., 2006 and Rüsch et al., 2007a), which warrants further investigation of the ACC and other prefrontal areas involved in emotion regulation such as the orbitofrontal and dorsolateral prefrontal cortices.
We examined interhemispheric structural connectivity between these prefrontal regions in women with BPD and comorbid attention-deficit hyperactivity disorder (ADHD). This is a more homogeneous but representative subgroup of BPD because ADHD is very common in subjects with BPD (about 60% of adults with BPD have a lifetime history of ADHD; Fossati et al., 2002) and both disorders share key features such as emotional instability and impulsivity (Davids and Gastpar, 2005) that are linked to ACC function (Davidson et al., 2000). Because of ADHD comorbidity, recent findings of ACC volume reduction (Seidman et al., 2006) and alterations of functional connectivity (Tian et al., 2006) in ADHD add to the relevance of this brain region for our analyses (Makris et al., 2009). Based on these previous findings, our study was designed to test the hypothesis that interhemispheric structural connectivity between the ACC, orbitofrontal and dorsolateral prefrontal cortices is reduced in women with BPD and comorbid ADHD as compared with healthy women.
