The effects of single doses of chlorpromazine (100 mg) and lorazepam (0.5, 1 and 2 mg) were compared with placebo in a battery of tests of information processing, working and semantic memory. Peak saccadic velocity was used to provide a precise and reliable measure of sedation and its results were found to be consistent with those using visual analogue rating scales. Chlorpromazine 100 mg was equally sedative to lorazepam 2 mg. Lorazepam caused dose-dependent deterioration in performance in many of the memory tests, whereas an equally sedative dose of chlorpromazine did not. These data therefore support the view that benzodiazepine-induced amnesia is not secondary to sedation. Peak saccadic velocity has considerable advantages over visual analogue scales as a measure of sedation, since it is objective and has a demonstrated low coefficient of variation. It is suggested that saccadic eye movement measurement will permit considerably more reliable and precise separation of the sedative and amnestic effects of drugs and will allow investigation of amnesia caused by clinically relevant doses of psychotropic drugs.
An electro‐oculogram based eye tracking system (the Cardiff System for the Generation and Analysis of Saccades) was used to quantify smooth pursuit eye movements (SPEM) and saccadic intrusions in 20 chronic schizophrenic patients and 16 normal, healthy controls. Statistically significant differences were found between the two groups at all four target frequencies tested (0·2, 0·25, 0·33 and 0·5 Hz) in three measures of SPEM dysfunction (position error, velocity error and saccadic intrusions). Of the patients' position errors, 50–70 per cent were greater than the 95th percentile for controls. Velocity errors gave a similar range of SPEM dysfunction (50–65 per cent) but the frequency of saccadic intrusion abnormality was more variable (20–60 per cent). Position error and saccadic intrusions, at the fastest target speed, correlated with total BPRS scores. Extrapyramidal symptoms (Simpson and Angus) and abnormal involuntary movements also correlated with saccadic intrusions at 0·5 Hz. There were no significant correlations between SPEM dysfunction and age, duration of illness, negative symptoms (total SANS score) or current dose of antipsychotic drug treatment. Copyright © 1999 John Wiley & Sons, Ltd.
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