Discussion

This paper highlights: (a) high prevalences of psychological distress, self-harm and attempted suicide among 17-year olds, and (b) gender-, ethnic-, socioeconomic- and sexuality-based inequalities in who experiences these difficulties at this age.

High prevalences have also been recently reported elsewhere with 15.4% of 17- to 19-year-olds having reported ever self-harming or attempted suicide.² In contrast, lifetime self-harm prevalence in the UK adults was 6%^{Reference McManus, Gunnell, Cooper, Bebbington, Howard and Brugha8} and high psychological distress based on the K-6 in US adults was, for instance, 8.6%.^{Reference Prochaska, Sung, Max, Shi and Ong7}

Our findings reflect well-established higher prevalences in females. However, the male–female gap in self-harm at age 17 (males 20.1%, females 28.2%) was considerably narrower than at earlier ages (males 8.5%, females 22.8%),^{Reference Patalay and Gage4} highlighting the greater increase in self-harming in males between ages 14 and 17.

Ethnic differences were similar to those reported elsewhere for this generation whereby White adolescents report the highest levels of distress.² An exception is attempted suicide, which demonstrated few ethnic differences. The reasons for observed ethnic differences in distress and self-harm and the lack of ethnic differences in attempted suicide might include inequalities in support and access to services in ethnic minority groups.^{Reference Edbrooke-Childs and Patalay9}

Sexual minority adolescents report the highest prevalences, with around 2–4 times the rates of self-harm and attempted suicide compared with their heterosexual peers. These findings highlight the need to better support this group and for parents, educators and clinicians to be aware that sexual minority adolescents might be struggling and need appropriate support, as they often also experience greater bullying, assault and a host of adverse co-occurring mental health related outcomes.^{Reference Amos, Manalastas, White, Bos and Patalay10}

The distribution of psychological distress scores (Supplementary Fig. 1) highlighted that although the mean scores in the socioeconomically disadvantaged group are higher, they are also more dispersed, with more disadvantaged adolescents reporting both higher and lower distress. Of note, prevalence of attempted suicide was almost double (around 12%) in the poorest two quintiles compared with the other income groups.

Like all longitudinal cohorts, MCS suffers from non-random attrition, and although this is accounted for by weights in analyses it is possible that the loss-to-follow-up of more disadvantaged participants might result in underestimation of prevalences. At age 14, the symptom measure included was different, precluding making any direct comparisons in distress prevalences between ages 14 and 17.

Age 17 marks an important age before many key life transitions, including the ending of compulsory education and moving away from home. With the ending of support from Child and Adolescent Mental Health Services (CAMHS) around this critical age, many young people fall through the gaps between CAMHS and adult mental health services, potentially further worsening outcomes at the precise time when support is most required.^{Reference Singh, Paul, Ford, Kramer, Weaver and McLaren11} These findings underline the urgent mental health support need in this generation. On the cusp of adulthood, they warn of a further widening in health, economic and social inequalities.