Reports of volumetric abnormalities in the anterior cingulate cortex (ACC) in adults with established borderline personality disorder (BPD) are inconsistent, and it is not known whether such abnormalities are present early in the disorder. We aimed to investigate ACC volume in a first-presentation teenage BPD sample with minimal exposure to treatment. Fifteen female BPD patients and 15 healthy female control participants underwent magnetic resonance imaging (MRI) scanning. ACC volumes were estimated using a reliable method that accounts for inter-individual variation in sulcal morphology, and measurements were compared between the two groups. Analysis of variance revealed a decrease in volume of the left ACC in BPD patients compared with control participants. This volumetric change was correlated with parasuicidal behavior and impulsivity. A measure of ACC volume asymmetry was also correlated with fear of abandonment symptoms. Our results suggest that ACC volumetric abnormalities early in the course of BPD might be related to clinical correlates of the disorder. Longitudinal studies are needed to examine the nature of this abnormality over the course of the disorder.
Neuroanatomical abnormalities have been reported in limbic and prefrontal regions in adult patients with borderline personality disorder (BPD) (Lyoo et al., 1998, Schmahl and Bremner, 2006 and Lis et al., 2007), and it has been suggested that these abnormalities might be associated with clinical features of the disorder. The anterior cingulate cortex (ACC) is involved in cognitive and affective functions (Bush et al., 2000, Allman et al., 2001 and Yücel et al., 2007) that are likely to underpin key borderline features, including affective instability, impulsivity, and cognitive distortions accompanying emotional distress.
Magnetic resonance imaging (MRI) volumetric studies of the ACC in BPD have been inconsistent in their findings. One region-of-interest based study of eight unmedicated adult female BPD patients (Tebartz van Elst et al., 2003) reported a 26% reduction in right cingulate gyrus (grey and white matter) volume. Another reported bilateral reductions in cingulate gyrus grey matter, coupled with increased ACC white matter, in 50 adult patients with various comorbidities (Hazlett et al., 2005). Voxel-based-morphometry studies of unmedicated adult BPD patients with comorbid disorders have reported both left-lateralized reductions (Minzenberg et al., 2008), and an absence of volumetric changes in the ACC (Rüsch et al., 2003).
One explanation for the above inconsistencies might relate to methodological differences in volumetric measurement. The ACC is a region of high morphometric variability, particularly with respect to the presence and extent of the paracingulate sulcus, which runs parallel to the cingulate sulcus along its rostro-caudal extent. We have previously demonstrated that PCS variability can alter the regional distribution of volume in the limbic ACC (ACCL; callosal sulcus extending to the cingulate sulcus) and the adjacent paralimbic cortex (ACCP; upper bank of the cingulate sulcus, extending to the paracingulate sulcus when present) by 39–88% (see Fig. 1 and Fornito et al., 2006). For automated voxel-based-morphometry approaches, the morphologically variable nature of this region increases the potential for errors in spatial normalization, making it unclear whether statistically significant findings reflect differences in volume, sulcal and gyral anatomy, or some combination of both (Bookstein, 2001). Consequently, morphometric studies of the region cannot ignore the influence that anatomical variation may have on volumetric estimates.
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Fig. 1.
Example of limbic (ACCL; highlighted in green) and paralimbic (ACCP; highlighted in blue) anterior cingulate regions when the paracingulate sulcus (red arrow) and superior rostral sulcus (yellow arrow) are present (right hand side) and absent (left hand side). See text (Section 2.3.1) for description.
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Another possible explanation for inconsistent findings in the literature is that studies have typically examined samples of adult patients with chronic BPD. Examining younger samples, earlier in the course of the disorder, has the potential to reduce the confounding influences of prolonged illness, treatment, and recurrent or chronic comorbidities (e.g., substance abuse, mood disorders) associated with BPD (Chanen et al., 2008c). The present study sought to extend this line of research in the context of a unique sample of young people with first-presentation BPD by investigating measures of ACCL and ACCP volume with a region-of-interest based methodology that takes into account individual variability in local sulcal morphology (Fornito et al., 2006).
