The benzodiazapine drug known as alprazolam is commonly sold under the trade name of Xanax, and it is often prescribed for anxiety, depression and sleep disorders. In addition to stress-reducing effects, Xanax also has sedative, hypnotic, anticonvulsant and muscle relaxant effects. Some of these properties may be mediated indirectly by affecting memory systems. In fact, alprazolam induces anterograde amnesia, promotes retrograde amnesia, changes risk taking and enhances memory gain.
Alprazolam is often associated with anterograde short-term memory loss for events that occur after taking the drug, in both human and nonhuman models. A respected study published in the November 1994 issue of "Psychological Medicine" illustrates these effects. Memory was assessed objectively and researchers found that Alprazolam caused impairments on a word recall task, and these lasted up to four months after stopping the drug. It did not, however, affect performance on an implicit memory or digit span task. Subjective measures of memory were more effected than objective measures. Alprazolam-induced anterograde amnesia is usually considered to be transient, yet those results suggested otherwise. A follow-up study, published in the January 1999 issue of "Psychological Medicine" revealed that the previous results were not effects of alprazolam, but were from the drug's interaction with practice effects on the tests used and the anxiety over repeated exposure to the test protocol.
The effects of alprazolam on retrograde amnesia are less clear, yet they are likely present as well. A study in the January 1998 issue of "Pharmacology" demonstrated retrograde amnesia in rats given alprazolam. Similar results were published in the August 2007 issue of "Behavioural Brain Research" using a related chemical, brotizolam. These data may be replicated in human studies and thereby support the more commonly obtained benzodiapine-induced anterograde amnesia.
A study in the May 2006 issue of "Experimental and Clinical Psychopharmacology" looked at a different aspect of alprazolam: its ability to reduce anxiety during simulated risk taking. The key measures in this study were responsiveness to rewards and losses, rate of updating expectancies about the value of risky alternatives -- learning/memory -- and consistency with which trial-by-trial choices match expected outcomes. The authors found that alprazolam produced increases in risk taking that were related to learning/memory but not motivation.
Time of day may play an important role in the effects of alprazolam on memory. A study in the October 1998 issue of the "Journal of Clinical Psychopharmacology" showed that alprazolam can, under some circumstances, enhance memory gain. A total of 64 subjects, in two groups, were given either a drug or placebo twice a day for 14 days. A salient increase in performance was indicated after drug administration in the alprazolam group compared with the control group results. Because the drug was administered at two different clock times, this study differs in protocol and results suggesting that a relationship between the two factors may explain the aberrant results.