Executive functions in cocaine-dependent patients with Cluster B and Cluster C personality disorders

Cocaine dependence often co-occurs with personality disorders from Clusters B and C, which are inherently associated with some of the executive dysfunctions found in addiction. We address the question of whether the comorbidity between cocaine dependence and different types of personality disorders is associated with differential profiles of executive deficits compatible with their personality dysfunction. We predicted that the comorbidity with Cluster B disorders would be associated with inhibition and shifting deficits, whereas the comorbidity with Cluster C disorders would be associated with working memory deficits.

We tested 107 participants (22 cocaine users with Cluster B disorders, 15 cocaine users with Cluster C disorders, 36 cocaine users without comorbidities, and 34 controls) using tests of working memory, attention, inhibition, and shifting. Groups were statistically matched on IQ and had no Axis I comorbidities (other than substance-related). Based on the performance of the control group, we obtained z-score composite measures of working memory, attention/inhibition, shifting, and global executive impairment. We tested group differences in these composite measures using univariate analyses of variance and Sidak tests corrected for multiple comparisons.

Cocaine users with Cluster B disorders had poorer attention/inhibition, whereas cocaine users with comorbid Cluster C disorders had poorer working memory. Cluster B and noncomorbid cocaine users (but not Cluster C users) differed from controls on the global executive impairment measure.

The comorbidity between cocaine dependence and personality disorders from Clusters B and C is associated with executive function deficits that are compatible with their respective personality dysfunctions.