Smooth pursuit eye movements in schizophrenia: effects of neuroleptic treatment and caffeine.

Abnormal smooth pursuit eye movement (SPEM) has been proposed as a trait marker in schizophrenia. We utilized high resolution infra-red oculography to measure SPEM in 11 neuroleptic-treated schizophrenic patients, 10 drug-free schizophrenic patients, and 11 normals. The most characteristic abnormality was a significant increase in saccadic intrusions during SPEM in schizophrenic patients (p less than .001). SPEM gain was reduced in schizophrenic patients (p less than .005). No significant effects of neuroleptic treatment on SPEM were found, including analysis of seven patients in whom paired data was available. We also measured SPEM prior to and after caffeine ingestion (10 mg/kg) in 10 normals. We found reduced saccadic interruptions as a result of caffeine ingestion compared with placebo (p less than .05). As caffeine has been shown to selectively increase dopaminergic neurotransmission in mesocortical neurons, further study utilizing dopamine agonists during SPEM in schizophrenic patients is warranted.