Neurological Soft Signs (NSS) and impairments in oculomotor saccadic paradigms are both frequent in patients with schizophrenia but their correlation has never been explored.Methods
78 patients with DSM-IV schizophrenia (including 43 non-treated) and 41 matched healthy controls were tested for NSS, and on three saccadic tasks: prosaccades, predictive saccades and memory-guided saccades) using infrared oculometry. We analyzed correlations between NSS scores and latencies in all three tasks, rate of errors in memory-guided saccades, and rate of anticipated predictive saccades.Results
No correlations were found in healthy controls. In the patient group, the NSS total and motor coordination scores were positively correlated with three saccadic variables: the latency of prosaccades (r = 0.36, p < 0.01 and r = 0.36, p < 0.01 respectively), of memory-guided saccades (r = 0.35, p < 0.01 and r = 0.32, p < 0.05 respectively) and, negative correlations were found, with the rate of anticipated predictive saccades (r = − 0.33, p < 0.01; r = − 0.35, p < 0.01 respectively). NSS total, motor coordination and sensory integration scores were correlated to the latency of non-anticipated predictive saccades (r = 0.34, p < 0.01; r = 0.24, p < 0.05 and r = 0.40, p < 0.001 respectively). The NSS total, motor integration and sensory integration scores were correlated with the rate of errors in memory-guided saccades (r = 0.38, p < 0.01; r = 0.37, p < 0.01 and r = 0.34, p < 0.01 respectively).Conclusions
These results support a common pathological mechanism with partial overlapping neural substrates between NSS and saccades in schizophrenia.