Assessment of the AccuSwayPLUS System in Measuring the Effect of Lorazepam on Body Sway in Healthy Volunteers

Aim: To assess the AccuSway(PLUS) system, which aims to quantify deficiency in human balance, using the measurement of the effect of lorazepam on body sway in healthy volunteers. Methods: A double-blind, randomised, placebo-controlled, two-way crossover study in 12 healthy male and female volunteers. Participants received a single oral dose of lorazepam 2mg and placebo, 1 week apart. Body sway was assessed using the AccuSway(PLUS) system, by measuring the length of the path of the centre-of-pressure (COP), and the area of the 95% confidence ellipse enclosing the COP (A95). Body sway was assessed at baseline and at 2, 3, 4, 6, 12, 18 and 24 hours after administration, in two positions: with the participants' eyes open and feet apart at hip's width (EOFA), and with their eyes shut and feet together (ESFT). Results: Statistically significant differences in body sway between lorazepam and placebo were detected for up to 18 hours after administration. The largest change in body sway was 2 hours post-dose, in the EOFA position; the mean (95% confidence interval) difference between lorazepam and placebo in fold change of A95 was 7.67 (3.88, 15.17), and in length of COP was 1.61 (1.23, 2.10). Conclusion: The findings confirm that the AccuSway(PLUS) system is a useful tool for detecting changes in body sway induced by centrally acting drugs.