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Abstract Background Teenage suicide-related behaviors have been highlighted in Japan in recent years, but the background factors and characteristics of these behaviors have not been clarified. Therefore, we investigated the characteristics of teenage suicide attempters who were admitted to an emergency room. Methods The subjects were suicide attempters in their teens and twenties who were admitted to the Critical Care Medical Center of Nippon Medical School Hospital between January 1, 2010 and December 31, 2021. The means of suicide attempt, sociodemographic data, psychiatric diagnoses, and causes and motives for suicide attempts were retrospectively examined from medical records. Teenage suicide attempters were compared to those in their twenties in regard to the acquired data, and logistic regression analysis was conducted to evaluate the influence on teenage suicide attempts by the aspects that have been shown to be closely associated with teenage suicides. Results Among 860 suicide attempters between 2010 and 2021, 59 (6.9%) were teenage suicide attempters and 216 (25.1%) were suicide attempters in their twenties. The large number of females, the history of self-harm, the great number of drug overdoses as a means of attempting suicide, and the large number of individuals with psychiatric disorders, especially with mood disorders and personality disorders, were commonly shared by suicide attempters both in their teens and twenties. On the other hand, family problems, school problems and autism spectrum disorder significantly influenced mostly teenage suicide attempters. Conclusions It was suggested that teenage suicide attempters may have attempted suicide due to environmental difficulties and conflicts about not being able to escape from them. It has become clear that teenage suicide attempters have unique characteristics and background factors, and that it is important to take these into account when taking measures to prevent teenage suicides.

Abstract Intellectual drug doping in athletics by using stimulants that affect central nervous system functions has been diversified. Stimulants are regulated by the World Anti-Doping Agency according to their levels of urinary concentration. Positron emission tomography could evaluate how stimulants affect central nervous system functions. We aimed to evaluate the effect of stimulants on brain function by examining the difference in brain dopamine transporter occupancy by PET after administration of dl-methylephedrine or pseudoephedrine at the clinical maximum daily dose. Four PET scans without and with drug administration (placebo, dl-methylephedrine 150 mg and pseudoephedrine 240 mg) were performed. The concentrations of dl-methylephedrine and pseudoephedrine in plasma and urine were measured. DAT occupancies in the striatum with placebo, dl-methylephedrine and pseudoephedrine were calculated by PET images. The urinary concentration of dl-methylephedrine (12.7 µg/mL) exceeded the prohibited concentration (10 µg/mL), but the DAT occupancy with dl-methylephedrine (6.1%) did not differ (p = 0.92) from that with placebo (6.2%). By contrast, although the urinary concentration of pseudoephedrine (144.8 µg/mL) was below the prohibited concentration (150 μg/mL), DAT occupancy with pseudoephedrine was 18.4%, which was higher than that with placebo (p = 0.009). At the maximum clinical dose, dl-methylephedrine was shown to have weaker effects on brain function than pseudoephedrine.

IntroductionMental rotation (MR) tasks of body parts involve anatomically interconnected brain systems. The systems are implicated in sensorimotor information integration and activate cortical motor-related areas, corresponding to the execution of similar motor tasks. In this study, we aimed to investigate the effect of varying the angle in the hand MR task on cerebral activation of the motor-related areas.MethodsTwenty healthy right-handed participants were recruited. We investigated cerebral activation while each participant decided whether a hand-palm image, rotated by 0°, 90°, 180°, and 270°, was a right or left hand.Results and discussionA significant negative correlation between the angle and brain activity was observed in the right and left supplementary motor area (SMA) and right posterior anterior cingulate gyrus. The SMA was inactivated with 180°- or 270°-rotated images in the regions of interest analysis. 180°- and 270°-rotated palms would be biomechanically difficult to position; thus, SMA deactivation may be closely associated with biomechanical constraints. This study provided novel findings regarding the neurophysiological mechanisms of motor imagery and may be useful in developing treatment plans using MR tasks during patient rehabilitation.