Lack of effects of guanfacine on executive and memory functions in healthy male volunteers
Guanfacine is an α2-adrenergic receptor agonist that has been shown to have beneficial effects on working memory and attentional functions in monkeys and in patients with attention deficit hyperactivity disorder.
The aim of this study was to further investigate the cognitive-enhancing properties of guanfacine using an established battery of tasks measuring executive and memory functions.
Sixty healthy male volunteers were randomised into three groups. Cognitive testing was performed from +2 to +4 h after double-blind administration of a single oral dose of 1 or 2 mg of guanfacine or placebo.
Systolic blood pressure was significantly reduced by both doses of guanfacine at the end of the testing session. There were no statistically significant effects on any of the cognitive measures. Two trend effects were observed with poorer performance on digit span backward and slower ‘Go’ reaction times after guanfacine.
This study found no improvement of prefrontal memory or executive functions after guanfacine. Negative effects on blood pressure and trend effects on digit span backward and go reaction time indicate a mild sedative effect of guanfacine at these doses, possibly via mechanisms of autoreceptor down-regulation.
KeywordsAlpha receptor Guanfacine Noradrenaline Memory Prefrontal
We thank Dr. Danielle Turner for help with preparing the study, the nurses and administrative staff at the Wellcome Trust Clinical Research Facility (WTCRF) for professional collaboration and all volunteers for participation. The study was performed at the WTCRF, Addenbrooke's Centre for Clinical Investigation (ACCI) Cambridge, supported by a Wellcome Trust Programme Grant (TWR, BJS), the Isaac Newton Trust (TWR, UM) and the Alexander von Humboldt-Foundation (Feodor Lynen-Fellowship awarded to UM) and completed within the MRC Centre for Behavioural and Clinical Neuroscience.
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