The complex relationships between executive functions and positive symptoms in schizophrenia.

BACKGROUND: Relationships between performance on various tests of executive functions and positive symptoms, especially delusions and hallucinations, have not been found consistently. This may be related to method of rating symptoms, to possible interactions between them, as well as to the low specificity of the cognitive test measures used. In this study, we have investigated the relationships between different aspects of positive symptomatology and several executive subprocesses. METHOD: Stable schizophrenia patients (n=96) were assessed for disorganization, delusion and hallucination symptoms rated from the Scale for Assessment of Positive Symptoms and the Scale for Assessment of Negative Symptoms. Interference sensitivity, inhibition and flexibility were assessed using the Wickens paradigm. The relationships between symptom dimensions as well as with cognitive and other potentially confounding variables were assessed using Pearson correlations and (simple and partial) stepwise regressions. RESULTS: Generally consistent with the cognitive constructs used to account for positive symptoms, the results indicated relationships between delusions, disorganization and inhibition, and between hallucinations and interference sensitivity. However, these relationships appeared more complex than expected, with some being dependent on interactions between symptoms. CONCLUSIONS: These results suggest: (i) that the global measures usually employed may not be appropriate for demonstrating specific relationships between symptoms and executive functions and (ii) that it is necessary to take into account the interactions between positive symptoms as well as with other factors to reveal these relationships.

Increased extrapyramidal symptoms in patients with schizophrenia and a comorbid substance use disorder.

Few data have been gathered about the impact of psychoactive substances on extrapyramidal symptoms (EPS) in schizophrenia, and so far, inconsistent results have been reported. We studied 41 outpatients with schizophrenia (based on DSM-IV criteria), who were divided into two groups: with (n = 17) and without (n = 24) a substance use disorder (alcohol, cannabis, and/or cocaine). Both groups were matched for sociodemographic data and psychiatric symptoms (Positive and Negative Syndrome Scale). EPS were evaluated with the Extrapyramidal Symptoms Rating Scale and the Barnes Akathisia Scale, and all patients were stable on either quetiapine or clozapine. Patients receiving anticholinergic drugs were excluded. Analyses of variance were conducted on both groups and showed that schizophrenia patients with a comorbid substance use disorder (especially cocaine) displayed more EPS compared with non-abusing patients.

Exploring cognitive complaints in schizophrenia: the subjective scale to investigate cognition in schizophrenia.

While it has become commonplace to test the various components of memory in schizophrenia with paper-and-pencil or in-lab tasks, very little data exist on the subjective complaints of patients regarding their memory. Few instruments have been designed to collect systematically the complaints of patients with schizophrenia. We present a work in progress on the Subjective Scale to Investigate Cognition in Schizophrenia (SSTICS), a 21-item, Likert-type scale that is simple and easy to use. It allows a quantitative approach to the subjective and cognitive dimensions of schizophrenia. Stip constructed the scale based on a questionnaire covering several cognitive domains: memory (working memory, explicit long-term memory), attention (divided, distractibility, alertness, sustained), language, and praxia. We evaluated the psychometric properties of the SSTICS in a population of 114 French-speaking patients in Montreal. Patients were recruited in the community and assessed with the Structured Clinical Interview for DSM-III-R (SCID), the Positive and Negative Syndrome Scale (PANSS), and the Extrapyramidal Symptoms Rating Scale (ESRS). Cognition was measured using the Rey Auditory Verbal Learning Test (RAVLT) (long-term memory), Controlled Oral Word Association Test (verbal fluency), and Trails A and B. Preliminary analyses showed very good internal consistency for the global score (alpha=0.88), and alphas varying from 0.57 to 0.72 for the subscales. Stability over time was very good. The principal components analysis accounted for a multiple structure. Correlations between subjective scores and objective cognitive assessment were significant for several domains. Validation of the SSTICS needs to be completed through further exploration of the factorial structure and testing of the English version.