Objective: Borderline personality disorder is characterized by a lack of effective regulation of emotional responses. The authors investigated the role of the endogenous opioid system and mu-opioid receptors in emotion regulation in borderline personality disorder.
Method: Mu-opioid receptor availability in vivo (nondisplaceable binding potential, or BP(ND)) was measured with positron emission tomography and the selective radiotracer [(11)C]carfentanil during neutral and sustained sadness states in 18 unmedicated female patients with borderline personality disorder and 14 healthy female comparison subjects.
Results: Patients showed greater regional mu-opioid BP(ND) than did comparison subjects at baseline (neutral state) bilaterally in the orbitofrontal cortex, caudate, and nucleus accumbens and in the left amygdala, but lower BP(ND) in the posterior thalamus. Sadness induction was associated with greater reductions in BP(ND) (endogenous opioid system activation) in the patient group than in the comparison group in the pregenual anterior cingulate, left orbitofrontal cortex, left ventral pallidum, left amygdala, and left inferior temporal cortex. Patients showed evidence of endogenous opioid system deactivation in the left nucleus accumbens, the hypothalamus, and the right hippocampus/parahippocampus relative to comparison subjects. Correlations of baseline measures with the Dissociative Experiences Scale and endogenous opioid system activation with the Barratt Impulsiveness Scale did not remain significant after correction for multiple comparisons.
Conclusions: Differences exist between patients with borderline personality disorder and comparison subjects in baseline in vivo mu-opioid receptor concentrations and in the endogenous opioid system response to a negative emotional challenge that can be related to some of the clinical characteristics of patients with borderline personality disorder. The regional network involved is implicated in the representation and regulation of emotion and stress responses.