Objective This study aimed to determine the tic aggravation event rate and cumulative incidence rate in the use of methylphenidate (MPH) treatment in attention-deficit/hyperactivity disorder (ADHD) and the factors that influence tic aggravation.Methods We conducted a retrospective chart review of children and adolescents aged between 6 to 15 years, who were diagnosed with ADHD from January 2017 to December 2019. A total of 121 subjects were included. The MPH dosage, psychiatric family history, comorbidity and past history of tics were assessed through chart review and the psychological examinations data were included. Collected data were analyzed using Cox regression and Kaplan-Meier survival analysis.Results Tic aggravation event rates without a past history of tics were 2.9% with MPH treatment in ADHD. Past history of tics, total MPH dosage and age were the factors associated with tic aggravation ([HR 21.46, p<0.001], [HR 0.94, p=0.023], [HR 0.79, p=0.021] for each). Cumulative incidence of tic aggravation was different between groups with or without past tic history. When treated with MPH, all tic aggravation appeared within approximately eight months but for subjects with a past history of tic, aggravation showed within approximately six months (p<0.001).Conclusion Tic aggravation event rate was significantly low especially in the group without a past history of tics with the use of MPH in ADHD. However, a thorough assessment of past history of tics, and close monitoring during the first six-eight months of treatment with MPH is needed to avert a potential worsening of tics.

Background: Self-harm is an important public health problem with increasing incidences among adolescents for over a decade. This study aimed to identify factors associated with self-harm in adolescent psychiatric inpatients in Korea. We also investigated clinical characteristics associated with nonsuicidal self-injury disorder (NSSI-D) and suicidal behavior disorder (SBD) according to the Diagnostic and Statistical Manual of Mental Disorders 5 criteria.Methods: This retrospective study included 215 adolescents aged between 12 to 18 years, who were admitted to the psychiatric ward of Samsung Medical Center, Seoul, Korea, from January 2014 to February 2021. Participants were divided into three groups according to NSSI-D and SBD diagnostic criteria. Collected data were analyzed using chi-square test and analysis of variance test.Results: Overall, 57.7% of the participants (n=124) reported self-harm at least once in their lives. Patients with self-harm were more likely to have experienced parental conflict, parent-child relational problems, and verbal, physical, or sexual abuse. Among the three groups divided according to NSSI-D and SBD diagnostic criteria, patients with both NSSI-D and SBD were more likely to have experienced parent-child relational problems than those with either NSSI-D only or SBD only.Conclusion: This study shows that parent-child relational problem is associated with high incidences of selfharm. Especially, the parent-child relational problem seemed to be a risk factor for SBD among patients with NSSI-D. These are important findings that provide an understanding of the self-harm characteristics and therefore improve prevention and treatment strategies in psychiatric adolescent patients.