Effects of a benzodiazepine on free recall of semantically related words

Although it is widely known that benzodiazepines impair episodic memory, few studies have investigated their effects upon specific processes involved in free recall. This study evaluated the acute effects of flunitrazepam (1.0 mg; 1.3 mg) and placebo in healthy volunteers on immediate and delayed free recall of word lists considering serial positions as well as semantic relations between words inserted in the middle of the lists (e.g. milk-cheese-butter). Flunitrazepam promoted a global amnestic effect, impairing recall in all serial positions except the last words (recency effect). Primacy and recency effects were preserved as indexed, respectively, by larger recall of the first and last words in relation to adjacent items. Facilitation in recall of semantically related words was not impaired by the drug when compared to recall in adjacent positions, in spite of a dose-dependent diminution of the number of words recalled also in mid-list positions. Flunitrazepam-induced deficits were interpreted as impairment in the formation of new associations between items, or groups of items in the case of related words, and context.