Three anxiolytic drugs (bromazepam 3 mg, buspirone 10 mg, and clobazam 10 mg p.o.) were evaluated for their effects on memory, psychomotor performance and subjective response in a double-blind, placebo-controlled, crossover study in 20 healthy volunteers. At each session, measurements were made before and 2 and 6 h after drug administration. The psychometric tests used were the images test, digit/symbol substitution test (DSST), choice reaction time (CRT), and critical fusion frequency (CFF). Free recall after 30 s in the 2-hour session was altered for all 3 drugs as compared to placebo (p < 0.01), but in the 6-hour session only bromazepam showed a significant difference (p < 0.05). The number of symbols reproduced by subjects during DSST was significantly decreased by bromazepam and buspirone as compared to placebo (p < 0.05), whereas clobazam showed no differences with placebo. Analysis of variance for all four treatments (the 3 drugs and the placebo) showed no differences at recognition time or for motor response in CRT, except between bromazepam and clobazam after 6 h (p < 0.05). None of the drugs altered performance during CFF (except bromazepam), and clobazam actually improved performance. All the drugs studied disturbed acquisition phenomena or restitution of memory; however, only bromazepam and buspirone significantly modified performance during DSST and disturbed the recognition and processing of sensory data.

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