A/HRC/43/39 communal spaces disappear. Such situations can induce problems of a psychological nature, such as grief, non-pathological distress, depression and anxiety disorders, including posttraumatic stress disorder. Cumulative trauma experienced pre- and post-migration also contributes to overall child distress.22 43. As noted by the World Health Organization (WHO), mental health is more than the absence of mental disorders; mental health is fundamental to health and overall wellbeing.23 44. According to WHO, up to 50 per cent of mental disorders during adulthood have their onset in adolescence and up to 20 per cent of children and adolescents experience mental disorders. 24 An important problem is that about 70 per cent of children and adolescents with mental disorders do not receive an appropriate intervention at the right time.25 45. Despite this grave situation, mental health issues among children and adolescents are often neglected owing to lack of awareness or existing stigma of mental disorders and they remain untreated. If left untreated, mental disorders may have far-reaching negative impacts on a young person’s development, educational attainment and transition to adulthood. 26 Mental disorders at a young age can lead to discrimination, stigma and exclusion, and may even result in limited access to social, education and health services. 46. The lack of priority accorded to child and adolescent mental health is also reflected in the limited global coverage of prevalence data for mental disorders in this group. Average global coverage of prevalence data for mental disorders in children and adolescents aged 5 to 17 was 6.7 per cent. Of 187 countries, 124 had no data for any disorder. Without focused strategies to address the paucity of epidemiological data, poor coverage in both high-income countries and low- and middle-income countries will present a major challenge for child and adolescent mental health advocacy and the planning and allocation of the scarce resources available for child and adolescent mental health.27 47. Mental health is also a major concern for children themselves. In its report entitled “Voices of children and young people: child helpline data for 2017 & 2018”, Child Helpline International indicated that the two most significant concerns for children contacting its member helplines related to abuse and violence on the one hand and to mental health on the other. Suicidal thoughts, fear and anxiety were the most significant issues children and young people talked about in relation to mental health. Physical and emotional abuse were the most significant issues in the abuse and violence category. The findings were based on data received from child helplines in 84 countries and territories around the world, underlining their global relevance. B. Main negative effects of violence on children’s mental health 48. In considering the impact of violence on children’s mental health, it is important to recall the different types of negative effects it can have, as well as the differences between children’s experience of violence across the life course. 22 23 24 25 26 27 Teena M. McGuinness and Simone C. Durand, “Mental health of young refugees”, Journal of Psychosocial Nursing and Mental Health Services, vol. 53, No. 12 (December 2015). WHO, “Mental health action plan 2013–2020” (2013). See WHO key facts on adolescent mental health, available at www.who.int/news-room/factsheets/detail/adolescent-mental-health. Mental Health Foundation, “Children and young people”, available at www.mentalhealth.org.uk/a-toz/c/children-and-young-people. See WHO key facts on adolescent mental health. See H.E. Erskine and others, “The global coverage of prevalence data for mental disorders in children and adolescents”, Epidemiology and Psychiatric Sciences, vol. 26, No. 4 (August 2017). 9