Relationships between performance on various tests of executive functions andpositive symptoms, especially delusions and hallucinations, have not beenfound consistently. This may be related to method of rating symptoms, topossible interactions between them, as well as to the low specificity of thecognitive test measures used. In this study, we have investigated therelationships between different aspects of positive symptomatology andseveral executive subprocesses.

Stable schizophrenia patients (n=96) were assessed for disorganization,delusion and hallucination symptoms rated from the Scale for Assessment ofPositive Symptoms and the Scale for Assessment of Negative Symptoms.Interference sensitivity, inhibition and flexibility were assessed using theWickens paradigm. The relationships between symptom dimensions as well aswith cognitive and other potentially confounding variables were assessedusing Pearson correlations and (simple and partial)stepwise regressions.

Generally consistent with the cognitive constructs used to account forpositive symptoms, the results indicated relationships between delusions,disorganization and inhibition, and between hallucinations and interferencesensitivity. However, these relationships appeared more complex thanexpected, with some being dependent on interactions between symptoms.

These results suggest: (i) that the globalmeasures usually employed may not be appropriate for demonstrating specificrelationships between symptoms and executive functions and(ii) that it is necessary to take into account theinteractions between positive symptoms as well as with other factors toreveal these relationships.