Effects of hypnotics on prefrontal cortex activity during a verbal fluency task in healthy male subjects: A near-infrared spectroscopy study.

Abstract

To assess the effects of hypnotics on prefrontal cortex activity in healthy subjects using near-infrared spectroscopy (NIRS) in a double-blind, placebo-controlled crossover trial. Eighteen healthy males received acute doses of ramelteon (8mg), triazolam (0.125mg), or placebo in a predetermined randomization schedule, with a washout period of more than 1week. All subjects performed a verbal fluency task during NIRS assessments at baseline and at 1 and 4hr post-dose. The number of words correctly generated during the task (behavioral performance) and scores on the Stanford Sleepiness Scale (SSS) were also recorded at each test time. Compared with the placebo, triazolam (0.125mg) significantly decreased oxyhemoglobin (oxy-Hb) concentration change in NIRS during the posttask period and significantly increased behavioral performance, whereas triazolam (0.125mg) and ramelteon (8mg) significantly increased SSS scores. The differential effects of two types of hypnotics on oxy-Hb change measured by NIRS were observed in acute dosing, suggesting that when assessing brain activity of patients with psychiatric disorders, researchers should consider how certain types of hypnotics can influence brain function. This would also provide useful information to clinicians when prescribing hypnotics suitable for their patients' conditions.