The assessment of residual effects of a single dose of diazepam on visually-defined EEG patterns

The aim of this single-blind study was to evaluate the residual effects of a 10-mg dose of diazepam on cortical activation 11 h after oral intake. The electroencephalographic segments (from O1-O2) delimited by a sequence of photic stimuli presented every 10 sec during a simple reaction-time task (36 min duration) were arbitrarily classified into nine cerebral patterns (EEGP). EEGP segment classifications were grouped into six peri-stimulus transitions expressed in percentages: alpha-blockade; alpha-persistence; beta-persistence; alpha-induction; activation and deactivation. A sample of 42 young healthy university students (21 females and 21 males) each underwent three counterbalanced experimental conditions (control, placebo and diazepam). Diazepam affected all the subjects, although the women showed a greater number of EEGP transitions which indicated deactivation, than did the men. The results show that this type of visual EEG analysis is a useful technique for detecting the residual effects of benzodiazepines.