human psychopharmacology Hum Psychopharmacol Clin Exp 2006; 21: 101–108. Published online 28 December 2005 in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/hup.747 Diazepam-induced prospective memory impairment and its relation to retrospective memory, attention, and arousal Jill B. Rich 1 *, Eva Svoboda 2,3 and Gregory G. Brown 4 1 Department of Psychology, York University, 4700 Keele Street, Toronto, Ontario, Canada M3J 1P3 2 Department of Psychology, University of Toronto, 100 St. George Street, Toronto, Ontario, Canada M57 3G3 3 Rotman ResearchInstitute, Baycrest Centre for Geriatric Care, 3560 Bathurst Street, Toronto, Ontario, Canada M6A 2E1 4 Department of Psychology, San Diego VAMC, 3350 La Jolla Village Dr., La Jolla, CA 92161, USA The amnestic effects of benzodiazepines are well documented on a variety of memory tasks. However, prospective memory (PM), or remembering to execute an action at a future time, has not been studied previously. This study examined the effect of diazepam on word list recall, PM, sustained attention, and subjective ratings of arousal. Forty-eight healthy participants, aged 19–35, received an average of 0.19mg/kg oral diazepam or placebo in a double-blind manner. Retrospective memory and PM were assessed by free recall of unrelated word lists and by instructing participants to request a hidden belonging at the end of the session, respectively. Sustained attention was measured by multiple trials of a digit cancellation task, and subjective arousal was assessed by self-ratings of drowsiness. Diazepam impaired performance on all measures, including PM. Reduced PM performance was associated with decreased subjective arousal in the diazepam group but was unrelated to sustained attention. This is the first report of the effects of benzodiazepines on prospective remembering, and further supports the view that the arousal/attentional system is composed of partially independent subsystems that have differential relationships to memory. Copyright # 2005 John Wiley & Sons, Ltd. key words — prospective memory; memory; benzodiazepines; diazepam; attention; arousal INTRODUCTION Benzodiazepines are frequently prescribed for their sedative, anxiolytic, and muscle-relaxant effects. Their transient deleterious effects on cognitive func- tions, namely arousal and memory, are also well established in the literature (for reviews, see Buffett-Jerrott and Stewart, 2002; Curran, 2000). Although sedation declines with increased drug tolerance (Curran, 2000), impaired memory func- tioning can be a lasting problem (Curran et al., 1994; Tata et al., 1994). Because of the importance of memory in everyday functioning, it has received extensive coverage in the psychopharmacological literature. Prospective memory (PM), defined as remembering to carry out a prespecified but delayed action, is a relatively new area of investigation in the field of cognitive psychology and among memory researchers (Kvavilashvili, 1987; Meacham and Singer, 1977). Although early PM studies focused primarily on aging (Einstein and McDaniel, 1990; Maylor, 1990; Moscovitch, 1982), the field has recently seen advances in both theoretical and empirical work (see Brandimonte et al., 1996). Despite the fact that this type of memory is particu- larly important for successful independent living, the effects of benzodiazepines on prospective remem- bering are unknown. Remembering to pay electricity bills, relay a tele- phone message, and take medicine every 4 h are examples of prospective remembering. PM comprises two components: remembering to perform an action at the appropriate time (prospective component) and remembering the content of the action (retrospective component, Brandimonte et al., 1996; Burgess and Shallice, 1997). The timeliness factor is crucial for successful prospective remembering (there is no need Received 14 June 2005 Copyright # 2005 John Wiley & Sons, Ltd. Accepted 31 October 2005 * Correspondence to: Dr Jill B. Rich, Department of Psychology, York University, 4700 Keele Street, Toronto, Ontario, Canada M3J 1P3. Tel: (416) 736-5115-ext 30561. Fax: (416) 736-5814. E-mail: jbr@yorku.ca