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Abstract:
Early reports suggested that benzodiazepine and
anticholinergic drugs may provide models for the patterns of
cognitive deficits observed in different clinical populations.
However, results of more recent studies comparing effects of the
two types of drug have generally revealed similar profiles of
deficits. The purpose of the present study was to directly compare
effects of the benzodiazepine lorazepam and the anticholinergic
scopolamine at comparable doses on a broad range of memory and
cognitive measures. Forty-eight healthy adult volunteers
participated in a double-blind, double-dummy design in which drug
condition (2.0 mg/70 kg oral lorazepam, 0.6 mg/70 kg subcutaneous
scopolamine, and placebo) was manipulated between subjects (16 per
drug condition), and data were collected at selected timepoints
following drug administration. Relative to placebo, lorazepam and
scopolamine produced similar decrements in psychomotor, recognition
memory, and free recall performance, and neither drug affected
negative priming. Lorazepam, but not scopolamine impaired working
memory performance. The two drugs also produced different patterns
of effects on metamemory judgments and on performance in the Stroop
interference paradigm. Consistent with their distinct neurochemical
profiles, lorazepam and scopolamine produce different patterns of
cognitive effects.
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