Body sway and the effects of psychoactive drugs — a review

The published literature on the effects of single oral doses of psychoactive drugs on body sway in normal healthy young volunteers has been reviewed. Several methods are used to quantify sway objectively, including mechanical devices, balance platforms, and non‐contact techniques. No one method emerges as being most appropriate for use in psychopharmacology. Total sway path and Fourier analysis are the variables commonly studied. Although many factors can influence sway they have little impact on well‐designed studies. Ethanol has been consistently shown to increase body sway at doses above 0·5 g/kg, benzodiazepines also increase sway; both probably acting at a central site(s). Various other psychoactive drugs have been shown to increase sway; however, none has yet been shown to decrease the amount of sway in normal subjects. The objective measurement of body sway is therefore a useful test for inclusion in a battery of tests for studies in human psychopharmacology. It also has a potential application in other areas of research requiring the assessment of central nervous system function, and in other subject groups, such as the elderly.