The effects of single doses of lorazepam on event-related potentials and cognitive function

Twelve healthy participants received double‐blind single doses of lorazepam 1 mg, 2 mg and placebo at weekly intervals using a Latin square design. Prior to administration and 2 h afterwards, a battery of tests was used to assess psychomotor and cognitive function and to elicit event‐related potentials (ERPs), concentrating on the P300 wave. This wave, elicited reliably using two paradigms (Rugg– Nagy and ‘oddball’), was prolonged in latency and reduced in amplitude in a dose‐related manner by lorazepam. Cognitive and psychomotor performance was impaired by the benzodiazepine. Subjective sedation was induced by the drug. However, no relationships were found between drug effects and the ERPs and on psychological functioning. It was concluded that the lack of correlation could reflect relatively low participant numbers or carry‐over effects of the medication.