Effects of low-dose mirtazapine on driving performance in healthy volunteers.

OBJECTIVE: This study aimed to assess whether a lower initial dose of mirtazapine can lessen the harmful effect on driving performance or not in a double-blinded, placebo-controlled crossover trial. METHODS: Thirteen healthy men received 8 days of continuous nocturnal doses of mirtazapine at 7.5 mg or 15 mg, or placebo. At baseline and on days 2 and 9, subjects performed three driving tasks (road-tracking, car-following, and harsh-braking tasks) using a driving simulator and a Continuous Performance Test. Stanford Sleepiness Scale (SSS) scores were also assessed. In the mirtazapine 7.5 mg series, 15 mg of mirtazapine was additionally administered on day 9, followed by all the same assessments on day 10. RESULTS: Mirtazapine 7.5 mg had no significant effects on any tasks except for SSS compared with placebo. Mirtazapine 15 mg impaired road-tracking task and SSS. The increase in mirtazapine dose also had no significant effects on any tasks compared with those before dose increase. CONCLUSIONS: Mirtazapine 7.5 mg did not cause driving impairment compared with mirtazapine 15 mg, while both doses of mirtazapine produced subjective somnolence. The increase in mirtazapine had no detrimental effects on psychomotor performance. Initial low-dose mirtazapine may be safer for automobile driving than the normal starting dose.

Effects of repeated dosing with mirtazapine, trazodone, or placebo on driving performance and cognitive function in healthy volunteers.

OBJECTIVE: This study aimed to evaluate the effects of repeated treatments with the sedative antidepressants mirtazapine and trazodone on driving performance and cognitive function. METHODS: Nineteen healthy men received continuous nocturnal doses of 15-mg mirtazapine , 25-mg trazodone, or placebo for 8 days in a double-blinded, three-way crossover trial. Subjects were asked to perform three driving tasks (road tracking, car following, and harsh braking) using a driving simulator and cognitive tasks (the Wisconsin Card Sorting Test, Continuous Performance Test, and N-back Test) at baseline and on Days 2 and 9. Stanford Sleepiness Scale scores were also assessed. RESULTS: Mirtazapine significantly increased the standard deviation of lateral position in the road-tracking task as compared with trazodone on Day 2. Mirtazapine significantly increased Stanford Sleepiness Scale scores as compared with trazodone and placebo. For the remaining tasks, no significant effects of treatment were observed. CONCLUSIONS: Acute treatment of mirtazapine impaired road-tracking performance and increased sleepiness, but sedative effects disappeared under repeated administrations. Trazodone did not affect driving performance or cognitive function under acute or repeated administrations. Both initial sedative effects and pharmacological profiles should be taken into consideration when using sedative antidepressants.

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

RATIONALE: Japanese researchers have recently conducted studies using near-infrared spectroscopy (NIRS) to help diagnose psychiatric disorders based on changes in brain activity. However, the influence of psychotropic drugs on NIRS measurements has not been clarified. OBJECTIVE: To assess the effects of sedative antidepressants on prefrontal cortex activity in healthy subjects using NIRS in a double-blinded, placebo-controlled, crossover trial. METHODS: Nineteen healthy males received nocturnal doses of mirtazapine 15 mg, trazodone 25 mg, or placebo for eight consecutive days in rotation, with a washout period of more than 1 week between each rotation. Subjects performed a verbal fluency task during NIRS on a total of seven occasions during the study period: more than a week prior to receiving the first dose of the first medication; and on days 2 and 9 of each rotation. The number of words correctly generated during the task (behavioral performance) was also recorded. Stanford Sleepiness Scale (SSS) scores were determined each day. RESULTS: Mirtazapine 15 mg significantly increased oxyhemoglobin (oxy-Hb) concentration change in NIRS on day 9, compared to trazodone 25 mg and placebo. Mirtazapine 15 mg significantly increased SSS on day 2, compared to the other conditions. No significant differences in behavioral performance were observed. CONCLUSIONS: Administration of mirtazapine for eight consecutive days affected oxy-Hb changes on NIRS. This result indicates that researchers should consider how certain types of antidepressant could influence brain function when the brain activity of patients with psychiatric disorders is assessed.

Sexual dysfunction and hyperprolactinemia in Japanese schizophrenic patients taking antipsychotics.

This study aimed to estimate the prevalence of sexual dysfunction, evaluated by the Nagoya Sexual Function Questionnaire (NSFQ), and hyperprolactinemia in patients with schizophrenia and examine a relationship between sexual dysfunction and serum prolactin levels. This cross-sectional, comparative study was performed using a sample comprising 195 Japanese schizophrenic in- and outpatients treated with antipsychotics (117 males and 78 females). Data were collected from October 2009 to January 2010 using single, cross-sectional ratings of sexual function assessed by the NSFQ and concurrent measurement of serum prolactin levels. The prevalence of sexual dysfunction in patients with schizophrenia was high (males 66.7%; females 79.5%). Hyperprolactinemia (>25ng/ml) was highly prevalent among schizophrenia patients, affecting 53.8% of females and 51.3% of males. Among female patients, 16.7% had prolactin levels>100ng/ml. There was no relationship between sexual dysfunction and serum prolactin levels. The present study demonstrated a higher prevalence of sexual dysfunction and hyperprolactinemia in Japanese schizophrenia patients. Clinicians should keep these problems in mind and discuss potential solutions with patients to improve patients' quality of life and adherence to therapy.

Reliability and validity of a new sexual function questionnaire (Nagoya Sexual Function Questionnaire) for schizophrenic patients taking antipsychotics.

OBJECTIVE: This study aims to validate a new user-friendly sexual function questionnaire (Nagoya Sexual Function Questionnaire [NSFQ]) for schizophrenic patients taking antipsychotics. METHODS: Schizophrenic outpatients (men = 30, women = 30) were asked to fill out the NSFQ at initial entry into the research program (Time1) and again 1 to 2 weeks later (Time2). To assess the convergent validity of the NSFQ, at Time1, subjects were asked to fill out the Japanese version of the Udvalg for Kliniske Undersogekser Side Effect Rating Scale (UKU). To assess the discriminant validity of the NSFQ, at Time1, subjects were also asked to fill out the Japanese version of Epworth Sleepiness Scale. RESULTS: Results from Cronbach's alpha analysis indicated that the NSFQ demonstrated excellent internal consistency and scale reliability. The NSFQ also demonstrated strong test-retest reliability. The NSFQ total score was highly correlated with the UKU total score. The NSFQ was shown to have good convergent validity with the UKU. The NSFQ total score was not correlated with the Japanese version of Epworth Sleepiness Scale total score. CONCLUSIONS: This study revealed the internal consistency, test-retest reliability, and convergent and discriminant validities of the NSFQ.