Background: cognitive disorders are considered as key disfunctions in schizophrenia spectrum disorders and as risk factors of schizophrenia. The aim of study was to examine neurocognitive deficit in patients with schizophrenic spectrum disorders, its structure and risk factors of schizophrenia. Patients and methods: 42 patients were examined with the diagnosis of “schizotypal disorder” (F21.3–21.5 according to ICD-10, n = 20) and “paranoid schizophrenia” (F20.00 according to ICD-10, n = 22). The control group included 20 people who had no signs of mental disorder. Cross-sectional study used methods for cognitive functions assessment. Results: patients with schizotypal disorder and paranoid schizophrenia are united by a deficit in the speed of processing, in verbal, visual and working memory, executive functions with sufficiently preserved visual-constructive abilities. In patients with the schizotypal disorder, compared with patients with paranoid schizophrenia, sustained attention and taskswitching ability, the effectiveness of long-term memorization and visual-spatial abilities are preserved to a greater extent. We found a correlation between burdened heredity and reduced results of the “Ray–Osterritz figure” technique and between the frequency of seeking medical help and the indicator of the “TMT-B” tracking test. Patients with schizotypal disorder are more likely to received more than one antipsychotic. The cognitive functioning of patients taking first/second generation antipsychotic drugs or their combination does not differ. Conclusions: patients with schizotypal disorder show similar, but in contrast to patients with paranoid schizophrenia, less pronounced cognitive impairment. There is a link between the degree of visual-spatial ability and the family risk of psychosis. The frequency of seeking medical help (unfavorable course of the disease) is associated with task-switching ability. Antipsychotic polypharmacotherapy, subject to dosages, is not a significant factor in cognitive disorders.