The effect of level of depression on the use of visual analogue scales by normal volunteers.

1 In two separate studies, 102 normal male volunteers were screened for level of depression using the Zung Self-Rating Depression Scale (Zung, 1965). Eight high scorers and eight low scorers were selected for inclusion in each study. 2 There were marked differences in scores on the visual analogue mood scales of Bond & Lader (1974) between the high depressed (HD) and low depressed (LD) groups. 3 In the first study, subjects were given single doses of imipramine 50 mg and 100 mg, diazepam 10 mg, and placebo in a double-blind randomized crossover design with 1 week between treatments. Drug effects as assessed on visual analogue scales were significantly more marked in the LD than in the HD group, to the extent that the sedative effects of imipramine 50 mg and diazepam 10 mg were minimal or absent in the HD groups whereas these effects were clear and highly significant in the LD group. 4 In a second study, LD and HD volunteers were given more objective items to rate using visual analogue scales. Ratings of the size of each of a series of ten circles, and of the weight of a 'black box', were consistently and significantly lower in the LD than in the HD group. Significant differences between LD and HD groups were also found on a series of visual analogue scales expressing attitudes not directly related to mood. 5 It is concluded that normal volunteers with varying levels of depression cannot be considered as homogeneous in their mode of expression on visual analogue scales, and that this should be taken into account in the design and interpretation of studies involving the use of such scales.