Selective effects of clonidine and temazepam on attention and memory

Abstract

The present study compared the effects of clonidine and temazepam on performance on a range of tasks aiming to assess the role of central noradrenergic mechanisms in cognitive function. Fifteen healthy volunteers (seven male, eight female), aged 18-25 years, took part in a five-period crossover study in which they received placebo, temazepam (15 and 30 mg) and clonidine (150 and 300 microg) by mouth in counterbalanced order in sessions at least 4 days apart. A test battery was administered before treatment and at 45, 90 and 135 min after the dose. Performance on most tests was significantly impaired in a dose-related fashion, and subjective sedation was recorded for both drugs. The greatest impairments with clonidine were on attention in the presence of distractors. Clonidine did not affect the formation of new long-term memories, in contrast to temazepam, but did impair measures of working memory. Subjective effects, especially feelings of drunkenness and abnormality, were particularly marked with clonidine. These results support the suggestion that central noradrenergic function may be involved in preventing distraction, but do not confirm other reports suggesting that some aspects of performance are improved with clonidine.

Noradrenergic modulation of working memory and emotional memory in humans

“…In one study, lower and higher doses of clonidine (0.04 and 0.4 mg) impaired working memory but an intermediate dose (0.16 mg) had no effect (Jakala et al 1999a). In another, the deleterious effects of clonidine were more marked at a higher compared to a lower dose (0.30 vs 0.15 mg) (Tiplady et al 2005). In another investigation, Coull et al (1995b) found that 0.12 mg clonidine had no effect on spatial working memory but impaired visual working memory, whereas 0.20 mg improved spatial working memory with no effect on visual working memory.…”

Modular processes in mind and brain

“…This may be why, for example, in a study that used task comparison to determine which processes are affected by clonidine versus temazepam (known to have different pharmacological mechanisms) in which 11 tasks were used, each drug produced statistically significant effects on all except one of the tasks (Tiplady, Bowness, Stien, & Drummond, 2005). The processdecomposition approach might be more helpful.…”

Naturalistic Effects of Five Days of Bedtime Caffeine Use on Sleep, Next-Day Cognitive Performance, and Mood

“…The Arrow Flankers task 33 consisted of five stimuli presented in a row in the center of the screen and lasted 3 minutes. Participants were instructed to press left [4] or right [6] keys on the keypad corresponding to the direction of the central arrow as quickly as possible while ignoring the flankers, unless the flankers were crosses in which case participants were instructed not to respond.…”