Do comorbid personality disorders in cocaine dependence exacerbate neuroanatomical alterations? A structural neuroimaging study

Cocaine dependence (CD) is highly comorbid with personality disorders, with implications for poorer treatment response. The neurobiological mechanisms of this comorbidity are unclear. We aimed to test the role of comorbid personality disorders in the neuroanatomy of CD. We examined 4 groups using high-resolution structural neuroimaging, psychological questionnaires and cognitive tests: CD (n = 19), CD and personality disorder type B (CD + B, n = 21), CD and personality disorder C (CD + C, n = 13) and 21 controls. We compared groups in neuroanatomy and hypothesised that (i) CD would show altered striatal areas ascribed to reward processing (i.e., accumbens, caudate and putamen), (ii) CD + B and CD + C would show altered areas supporting emotional regulation/social valuation and anxiety/avoidance (i.e., OFC and amygdala). The CD + B group had larger caudate volumes than CD (p = .01, d = 0.94) and reduced lateral OFC thickness than CD + C (p = .056, d = 0.71). Exploratory correlations showed that altered neural integrity of the OFC and of the caudate nucleus in these groups exacerbated with worse personality disorder severity and impulsivity scores. CD with and without comorbid personality disorders may have partially distinct underlying mechanisms and targets for treatment.