Visual contrast sensitivity in schizophrenia and schizotypic disorder

Schizophrenia is characterized by a wide range of symptoms that also manifest themselves in other disorders, which served as the basis for the emergence of ideas about schizophrenia spectrum disorders. Studies indicate inconsistency of data on the characteristics of visual contrast sensitivity in schizophrenia and schizotypal disorder, which is part of the structure of schizophrenia spectrum disorders. The study involved 30 patients diagnosed with paranoid schizophrenia; 18 patients with schizotypal disorder and 30 people without psychopathology and neurological diseases. Contrast sensitivity was recorded when presenting Gabor elements with a spatial frequency from 0.4 to 10 cycles/deg, using the adaptive staircase procedure. Contrast sensitivity in both the schizophrenia group and the schizotypal disorder group was lower in the area of high spatial frequencies, compared to the conditionally healthy control. Thus, the identified disorders are common to both schizophrenia and schizotypal disorder. The obtained data are considered as evidence of a special nature of the discordance in the interaction of the magnocellular and parvocellular channels of the visual system with a shift towards the dominance of the magnocellular system.