Déficits des fonctions exécutives dans la schizophrénie selon les dimensions positive, négative et de désorganisation

Environmental dependency phenomena in schizophrenia: a pilot study

INTRODUCTION

Environmental dependency phenomena refer to the enslavement of patients' performances under the characteristics of the tasks and were first described in case of prefrontal lobe damage. Two forms of environmental dependency, executive and social, may be dissociated, which involve respectively dorsolateral and orbital prefrontal cortex (PFC) dysfunction. Schizophrenia is widely considered to be caused by PFC dysfunction, but no study to date has addressed environmental dependency in this pathology.

METHODS

We compared patients (N = 17) and healthy controls (N = 28) on a task dedicated to the study of environmental dependency.

RESULTS

Our results demonstrate the presence of environmental dependency in schizophrenia. Each form of environmental dependency can be highlighted independently, as previously demonstrated by studies with prefrontal patients.

CONCLUSIONS

These findings suggest specific prefrontal dysfunction for each subgroup of patients and demonstrate a dissociation between socio-cognitive and neurocognitive performance in schizophrenia. Additionally, we found relationships between symptomatology and environmental dependency. This pilot study supports the relevance of studying environmental dependency to highlight specific patterns of prefrontal disorders in schizophrenia, which may contribute to a better understanding of PFC dysfunction in schizophrenia.

Inferring about individual drug and schizotypy effects on cognitive functioning in polydrug using mephedrone users before and after clubbing

OBJECTIVE

Mephedrone has been recently made illegal in Europe, but little empirical evidence is available on its impact on human cognitive functions. We investigated acute and chronic effects of mephedrone consumption on drug-sensitive cognitive measures, while also accounting for the influence of associated additional drug use and personality features.

METHOD

Twenty-six volunteers from the general population performed tasks measuring verbal learning, verbal fluency and cognitive flexibility before and after a potential drug-taking situation (pre-clubbing and post-clubbing at dance clubs, respectively). Participants also provided information on chronic and recent drug use, schizotypal (Oxford-Liverpool Inventory of Feelings and Experiences) and depressive symptoms (Beck Depression Inventory), sleep pattern and premorbid IQ.

RESULTS

We found that (i) mephedrone users performed worse than non-users pre-clubbing and deteriorated from the pre-clubbing to the post-clubbing assessment; (ii) pre-clubbing cannabis and amphetamine (not mephedrone) use predicted relative cognitive attenuations; (iii) post-clubbing, depression scores predicted relative cognitive attenuations; and (iv) schizotypy was largely unrelated to cognitive functioning, apart from a negative relationship between cognitive disorganisation and verbal fluency.

CONCLUSION

Results suggest that polydrug use and depressive symptoms in the general population negatively affect cognition. For schizotypy, only elevated cognitive disorganisation showed potential links to a pathological cognitive profile previously reported along the psychosis dimension.