Executive functioning in individuals with schizophrenia and/or cocaine dependence.

Objective: Although little is known about neurocognition in Dual Diagnosis, it has been suggested that Schizophrenia (SZ) patients with comorbid substance use belong to a subgroup with lower genetic vulnerability to develop SZ and, consequently, they show better executive and social premorbid functioning. The first aim of this study was to assess the executive functioning, and the second one was to explore the effect of age of onset of substance use in neurocognition in SZ patients with cocaine dependence.

Methods: The total sample consisted of 95 male patients, aged 20 to 60 years, divided in three groups: one group with SZ and cocaine dependence (SZ+; n = 30), another group with SZ without cocaine dependence (SZ-; n = 30), and a control group with cocaine dependence without psychiatric comorbidity (COC; n = 35).

Results: We found a better executive functioning in both SZ+ and COC than SZ-. We observed a worse performance of SZ+ patients compared with COC in cognitive set-shifting regardless the age of onset of consumption.

Conclusions: The results agree with the hypothesis of a lower genetic vulnerability in SZ+ patients to develop psychosis compared with SZ-, who develop it without any additional trigger. However, future research is needed to clarify the current knowledge gaps.