Volumes of the hippocampus and amygdala in patients with borderline personality disorder: a meta-analysis.

Individuals with borderline personality disorder (BPD) often exhibit impulsive and aggressive behavior. The hippocampus and amygdala form part of the limbic system, which plays a central role in controlling such expressions of emotional reactivity. There are mixed results in the literature regarding whether patients with BPD have smaller hippocampal and amygdalar volume relative to healthy controls. To clarify the precise nature of these mixed results, we performed a meta-analysis to aggregate data on the size of the hippocampus and amygdala in patients with BPD. Seven publications involving six studies and a total of 104 patients with BPD and 122 healthy controls were included. A significantly smaller volume was found in both the right and left hippocampi and amygdala of patients with BPD compared to healthy controls. These findings raise the possibility that reduced hippocampal and amygdalar volumes are biological substrates of some symptoms of BPD.