Network analysis of cognitive deficit in patients with schizophrenia spectrum disorders

BACKGROUND: Cognitive impairments are found in 80% of patients with schizophrenia. The severity of these impairments significantly affects the recovery of patients in terms of social functioning. Network analysis is the most suitable approach for studying complex relationships among cognitive functions. AIM: To build a network model of neurocognitive functions for identifying both the severity of impairments in individual functions and the vertices central to the whole model. METHODS: The study included 115 patients with schizophrenia and schizophrenia spectrum disorders and a comparison group, comprising 99 healthy subjects. The severity of clinical symptoms was assessed using the PANSS, CDSS and YMRS, and the SAS and BARS for extrapyramidal symptoms and akathisia. Subjects from the comparison group completed screening questionnaires QIDS-SR and PQ-16. Neurocognitive functions were assessed using the BACS. RESULTS: The patients performed worse than the healthy subjects on all tests. In the cognitive network models of healthy subjects, fewer connections were revealed and the central place was occupied by working memory, the functioning of which depends upon everyday functioning in the community. In the cognitive models of patients there was a greater connectedness of neurocognitive functions. Furthermore, the central place of the networks in patients is occupied by the processing speed, evaluated primarily using the Symbol Coding test, which reflects the dependence of patient activity on lower-order functions. CONCLUSION: The processing speed deficit is key to schizophrenia and it may be considered a potential endophenotype of the disease.