[The effect of terguride on the dynamics and mean level of vigilance. A controlled electroencephalographic study with...

The influence of a 3-week medication period with terguride (trans-dihydro-lisuride) in a dosage of 2 X 0.2 mg/d per os upon the 10-min resting EEG of elderly, clinically normal volunteers (mean age 70 years was investigated. Eight subjects received placebo and 7 subjects received terguride under double-blind conditions. The EEG data were analysed, inter alia, by a newly-developed method of quantification which uses information on topographical relationships of the absolute alpha-powers provided by two anterior and two posterior leads. Under terguride, but not under placebo, a significant increase of subvigilant patterns was found. If one were to disregard the baseline situation, which was characterized in the present sample by a distinct restriction of the physiological dynamics of vigilance at a reduced level (dynamic rigidity), this finding would have to be interpreted as sedation. A non-physiological pre-drug situation was indicated by marked and sustained anteriorization of alpha-activity. Taking into account our additional finding that terguride, but not placebo, eliminates this non-physiological alpha-anteriorization, we interpret the increase of subvigilant patterns in the course of the recording period as a resolution of the preexisting dynamic rigidity and, consequently, as a therapeutically desirable effect.