Motion perception and form discrimination in psychiatric patients.

Former studies have suggested that schizophrenia and bipolar disorders (BPD) are associated with a deficiency in the magnocellular visual system. Nevertheless, these findings are still controversial. The aim of the present study is to analyze whether visual processing is affected in schizophrenia, BPD, and depression patients and to investigate whether these deficits are associated with symptoms severity, neuropsychological function and eye movements. Thirty psychiatric inpatients, with diagnoses of Schizophrenia, Depression, and Bipolar Disorder participated in the study. Symptoms severity was measured with Brief Psychiatric Rating Scales. Accuracy in motion and form perception was evaluated by motion and form coherence tests respectively. Smooth pursuit eye movements were measured with Eye Tribe infrared video-oculography system. Data were analyzed off-line to calculate gain, delay and maximum speed. The general cognitive abilities were tested by Raven's Matrices. Stroop Test and Attentive Matrix were used to assess attention and Digit Span Test for memory. Executive functions were evaluated using Tower of London test and a modified version of Wisconsin Card Sorting Test. All the scores were standardized according to age and gender. No significant differences emerged between psychiatric diagnostic groups concerning motion and form perception and eye movements parameters. When compared to the control group, patients showed impaired visual perception and higher delay and lower gain values. Linear regression analysis showed that motion perception performances were related significantly to general cognitive abilities, attention ability, executive functions and ocular motility and did not depend to symptoms severity. Form recognition was only related to executive functions. These preliminary findings confirm the hypothesis that visual perception deficits in psychiatric patients are related to cognitive impairment and oculomotor defects .