Acute dose-effects of scopolamine on false recognition

Rationale: Recently, there has been increased research interest in the phenomenon of false recognition, in which participants claim to recognize words that had not been presented during an initial study phase but that are associatively related to presented words. Acute administrati1on of the benzodiazepine hypnotic triazolam has been shown to decrease false recognition rates. However, no false recognition studies have examined the effects of scopolamine, an anticholinergic drug that might produce a different profile of memory-impairing effects than the benzodiazepines due to its distinct neurochemical profile. Objective: This study was designed to examine the acute dose-effects of scopolamine on false recognition. Methods: The effects of subcutaneously administered scopolamine (0.3 * 0.6 mg/70 kg) on performance in the Deese/Roediger-McDermott false recognition paradigm were examined in a repeated-measures placebo-controlled double-blind design in 18 healthy volunteers. Results: Scopolamine produced dose-related reductions in both true and false recognition rates, and induced a more conservative response bias relative to placebo for recollection-based ("remember") responses to studied words. Conclusions: While scopolamine's effects on false recognition are similar to those observed previously with triazolam, its effects on response bias may differ from those of triazolam.