Correlates between neurological soft signs and saccadic parameters in schizophrenia.

Objective: 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.