Attention-deficit/hyperactivity disorder (ADHD) youths have increased suicide risk. Nevertheless, the beneficial effects of methylphenidate (MPH) on suicide attempt have received relatively little attention. To investigate the MPH usage and the risk of suicide attempt among ADHD youths. We identified 84,898 youths less than 18 years old with ADHD diagnosis between 1997 and 2013 from National Health Insurance, and examined whether MPH use affected suicide attempt risk using Cox proportional-hazards models. Among ADHD youths, reduction of suicide risk was found in patients prescribed 90-180days of MPH after adjusting for confounding factors (hazard ratio (HR): 0.41, 95% confidence interval (CI): 0.19-0.90) and a greater reduction in those prescribed more than 180days of MPH (HR: 0.28, 95% CI: 0.17-0.48). We observed a 59% suicide attempt risk reduction among ADHD youths prescribed between 90 and 180days and a 72% risk reduction in those prescribed more than 180days of MPH. The protective benefit observed by the group prescribed MPH for longer duration underscores the importance of psychoeducation and compliance enhancement as part of ADHD management. Indication bias is identified as a limitation of this study, and future self-case control study to investigate the association between suicide attempt and ADHD medication is suggested. This nationwide population-based cohort study showed that among ADHD youths, reduction of suicide risk was observed in patients prescribed MPH for duration 90days and longer, underscoring the importance of appropriate ADHD pharmacotherapy and enhancing drug compliance.

The World Health Organization reports that, by 2030, depression is expected to be the largest contributor to disease burden. Only small proportion of patients with major depressive disorder (MDD) achieves remission and the majority of them do not achieve long-term functional recovery. One of the neuropsychological domains that have been shown to be particularly impaired in depression, is that of executive function (EF). We examined whether the patients with MDD with and without suicide attempts had deteriorated 'cool' EF and 'hot' EF. The study population comprised 34 MDD attempters, 36 MDD non-attempters, and 55 healthy controls. We adopted the symmetry span task (SSPAN) to measure the updating and the affective shifting task (AST) to measure the inhibition and set-shifting in general and in response to emotional material. The Iowa gambling task (IGT) was used to examine the affective decision-making ability. After controlling for PHQ-9, Anxiety (HADS), suicidal ideation, education year and gender, we reported that (1) the MDD non-attempters had worse updating than the healthy controls and the MDD attempters; (2) the MDD attempters had worse general inhibition (GI) than the healthy controls and the MDD non-attempters; (3) the MDD non-attempters had worse general set-shifting (GS) than the healthy controls and the MDD attempters; (4) there was no between-group difference in the 'hot' EFs; and (5) MDD attempters with longer durations (over 5 years) since last attempt had worse general inhibition. The disrupted 'cool' EFs patients with MDD are consistent with previous review and meta-analytic studies. On the other hand, the two groups with MDD performed similarly to the healthy controls in the 'hot' EF.