In recent years the incidence of adolescent mental health problems has been rising. But at the same time, risky behaviour such as substance abuse – which has been linked to such problems – has become less common. So what has been going on? Praveetha Patalay from University College London and Suzanne Gage from the University of Liverpool looked at how things have changed over a decade among millennials born in early 1990s and early 2000s.
Headlines about adolescents have been dominated in recent years by concerns about mental health and wellbeing.
We know the prevalence of mental health issues has been rising among this group – and that the phenomenon is not restricted to the UK: international comparisons have shown the trend is mirrored across the globe.
And there’s a growing recognition that adolescence is a key time in this respect – half of those who suffer later from a mental health disorder experience symptoms by the age of 14.
Yet we know from official reports that at the same time, some types of risky behaviour which are linked with poor mental health have become less common among the young. Adolescents in the UK are less likely to be under-age substance abusers, and the proportion of 14 year-olds who smoke regularly has dropped to just a quarter of what it was in 1982.
A new piece of research looks at how rates of different mental health and health related behaviours such as substance use but also sleep, weight perception and underage sex are changing.
The paper looks at data for two cohorts of UK adolescents – those who were 14 in 2005 and those who were the same age in 2015. It uses data from two UK birth cohort studies – 5,627 young people born in 1991-2 who were part of the Avon Longitudinal Study of Parents and Children, and 11,318 born 2000–02 who were part of the Millennium Cohort Study.
The researchers looked at trends in mental health problems such as depression and self-harm, and found a picture broadly similar to previous studies. These phenomena had become more prevalent over time, with the incidence of high levels of depressive symptoms rising from six per cent in 2005 to 15 per cent in 2015. In contrast with some other studies they found boys had suffered an increase just as great as girls.
Poor mental health in our teenage years can predict a whole range of negative outcomes later on – poor physical health, worse job prospects and poor personal relationships, for instance.
Behaviour and health
And yet these results showed significant drops in various types of behaviour which are linked with poor mental health. For instance, the proportion who had assaulted someone at age 14 dropped from 40 per cent in 2005 to 28 per cent in 2015. Fewer young people had tried alcohol, binge drinking, smoking or having sex by the age of 14.
In this sample, young people in 2015 were more likely to have later bedtimes, to wake up earlier and to sleep less than the recommended eight hours. They were more likely to see themselves as overweight and to have higher Body Mass Index, or BMI.
These relationships aren’t simple. Other factors have changed over time, too. For instance the proportion of young people from ethnic minority backgrounds has risen, though that was taken into account.
The researchers suggest that increasing trends in risky behaviours such as decreasing sleep times, increasing weight and poor body image need to be investigated as potential explanatory factors for increasing mental health difficulties experienced by adolescents.
But there are some clear findings from this study. The rapid increase in depressive symptoms, self-harm, obesity and loss of sleep in adolescents over the past decade is an important finding in itself, and understanding the reasons for this could be a priority for both practitioners and policy-makers.
Changes in millennial adolescent mental health and health-related behaviours over 10 years: a population cohort comparison study is research by Praveetha Patalay and Suzanne H Gage and is published in the International Journal of Epidemiology.