Facultad de Ciencias de la Salud

Cocaine addiction is frequently associated with different psychiatric disorders, especially schizophrenia and antisocial personality disorder. A small number of studies have used prepulse inhibition (PPI) as a discriminating factor between these disorders. This work evaluated PPI and the phenotype of patients with cocaine-related disorder (CRD) who presented a dual diagnosis of schizophrenia or antisocial personality disorder. A total of 74 men aged 18–60 years were recruited for this research. The sample was divided into four groups: CRD (n = 14), CRD and schizophrenia (n = 21), CRD and antisocial personality disorder (n = 16), and a control group (n = 23). We evaluated the PPI and other possible vulnerability factors in these patients by using different assessment scales. PPI was higher in the CRD group at 30 ms (F(3, 64) = 2.972, p = 0.038). Three discriminant functions were obtained which allowed us to use the overall Hare Psychopathy Checklist Revised score, reward sensitivity, and PPI at 30 ms to predict inclusion of these patients in the different groups with a success rate of 79.7% (42.9% for CRD, 76.2% for CRD and schizophrenia, 100% for CRD and antisocial personality disorder, and 91.3% in the control group). Despite the differences we observed in PPI, this factor is of little use for discriminating between the different diagnostic groups and it acts more as a non-specific endophenotype in certain mental disorders, such as in patients with a dual diagnosis.

This study reports experimental results from a clinical sample of patients with a cocaine-related disorder and dual diagnosis: Schizophrenia and Anti-Social Personality Disorder. Both types of patients as well as a non-clinical group of students performed two incentivized decision-making tasks. In the first part of the experiment, they performed a lottery-choice task in order to elicit their degree of risk aversion. In the second part, they decided in two modified dictator games aimed at eliciting their aversion to advantageous and disadvantageous inequality. It is found that the Anti-Social Personality Disorder group exhibits no significant differences from the non-clinical sample in either task. However, compared with the students’ sample, subjects from the group with schizophrenia show more risk aversion and exhibit more aversion towards disadvantageous inequality.

Objective:Schizophrenia, cocaine-related disorder, antisocial personality disorder, andpsychopathy share biological bases, but few studies discriminate between these disordersby means of prepulse inhibition. This work studies the phenotype of patients with cocaine-related disorders who are vulnerable to presenting a dual diagnosis of schizophrenia orantisocial personality disorder, by evaluating their prepulse inhibition, impulsivity and psych-opathy personality traits.Methods:The sample (n¼38) was divided into three groups: (1)cocaine-related disorder (8 individuals diagnosed with cocaine-related disorder who did notpresent any other mental disorder), (2) cocaine-related disorder and schizophrenia (n¼14),and (3) cocaine-related disorder and antisocial personality disorder (n¼16).Results:Theprepulse inhibition in the two groups with dual diagnosis was lower than that in thecocaine-related disorder group,F(2, 35)¼6.52,p¼.004, while there was no significant differ-ences between the two dual-diagnosis groups. Psychopathy was evaluated with the revisedHare Psychopathy Checklist and showed no correlation with the prepulse inhibition.Secondary psychopathy (impulsivity and poor behavior control), as evaluated with LevensonSelf-Report Psychopathy Scale, was related to the prepulse inhibition. Two discriminating functions were obtained that allowed prediction of patient inclusion in the groups usingthe prepulse inhibition and the revised Hare Psychopathy Checklist with a success rate of81.6% (cocaine-related disorder¼62.5%; cocaine-related disorder and schizophrenia¼78.6%;cocaine-related disorder and antisocial personality disorder¼93.8%). These results are dis-cussed in regard to the neurobiological implications of prepulse inhibition in dual diagnosis.Conclusions:The results suggest that the prepulse inhibition is a promising dual-diagnosisvulnerability marker in individuals with cocaine addiction, because prepulse inhibition defi-cits are related both to schizophrenia and antisocial personality disorder. In addition, pre-pulse inhibition, which is considered a good endophenotype for studies on the genetic andneurobiological basis of cocaine-related disorder and schizophrenia, could be used in thesame way in studies on antisocial personality disorder.