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Substance use and depression more closely linked for generation Z teens

Press release issued: 4 May 2021

Substance use and antisocial behaviour are more likely to go hand-in-hand with poor mental health for generation Z teens compared to millennial adolescents growing up a decade earlier, finds a new UCL study.

Researchers from the Centre for Longitudinal Studies (CLS) at the UCL Social Research Institute and the University of Liverpool analysed data collected from two cohorts, born a decade apart, when they were 14 years old. The younger generation Z group was made up of more than 11,000 young people born across the UK in 2000-02, who are being followed by the Millennium Cohort Study. The older group of millennials consisted of just over 5,600 people who were born in the Bristol area in 1991-92 and are being followed by the Children of the 90s study.

The research, published in the Journal of Adolescent Health, reveals that even though rates of alcohol consumption, smoking, and assault among young people fell over the 10 year period – between 2005-2015 – the association between these behaviours and depressive symptoms was stronger for generation Z.

Co-author, Dr Praveetha Patalay (UCL Centre for Longitudinal Studies and MRC Unit for Lifelong Health and Ageing) said: “While it’s good news that underage smoking and drinking appears to have become less common in more recent cohorts, we found that young people who did engage in these activities were more likely to also experience mental health difficulties compared to previous generations.”

The researchers examined the prevalence of mental ill-health, substance use, antisocial behaviour, high body mass index (BMI) and perception of excess weight among both cohorts at age 14, and then looked at how likely they were to occur together.

Rates of depression among adolescents had almost doubled in the 10 years between the two generations ­– from 9% to 16% – but prevalence of antisocial behaviour and substance use, behaviours which have been recognised as predicting poor adolescent mental health in previous studies, had decreased over the decade.

Rates of 14-year-olds assaulting someone on purpose had dropped from 40% to 32%. More than 52% of the millennials had tried alcohol by age 14, compared to less than 48% of those born a decade later, and, 9% of millennials had tried smoking cigarettes in adolescence, compared to 5% of generation Z.

Among both generations, prevalence of mental ill-health was higher among those who reported underage drinking, smoking and assault. However, these risky behaviours and mental ill-health were more likely to occur together among generation Z teens than millennials. For example, among generation Z, those who had tried smoking were almost twice as likely to also have depressive symptoms compared to millennial youths.

The researchers also examined the link between excess weight and poor mental health. They found that rates of obesity among young people had almost doubled over a decade,  from 4% to 8%. Generation Z teens were also more likely to perceive themselves as being overweight or obese compared to their older counterparts at the same age (33% versus 26%).  Among generation Z, those who were overweight or obese and those who perceived themselves to have a high BMI were more likely to also report depressive symptoms at age 14 compared to similar millennial adolescents a decade earlier.

Dr Patalay said: “Among young people in generation Z, it appears that engagement in risky behaviours has disproportionately reduced in those without mental health difficulties, meaning that substance use and antisocial behaviours have become over-represented among those with poor mental health. This closer link between depression and potentially health-harming activities among more recent generations is concerning, and should be considered in public health planning and clinical care provision.”

Co-author, Dr Suzanne Gage (University of Liverpool) added: “Substance use, antisocial behaviours, body image issues and depression tend to begin in adolescence, and have long lasting effects for individuals and society. This research reveals a closer link between these risky behaviours and poor mental health for more recent generations of teens. Understanding more about how these behaviours interact in adolescence will be vitally important for policy and practice, so future generations can be supported better.”

Further information

Paper: S Gage, P Patalay, ‘Associations between adolescent mental health and health-related behaviours in 2005 and 2015: A population cross-cohort study,’ is available on the Journal of Adolescent Health website.

Study methodology notes

Depressive symptoms

At age 14, young people in both studies answered 13 questions that assess the extent (not true, sometimes true, true) of difficulties in the previous two weeks such as feeling miserable, tired, lonely, crying and hating oneself. A score above an established threshold is indicative of suffering from depression.

Antisocial behaviour

Antisocial behaviour was assessed using questions ascertaining involvement in assault, rowdy behaviour, graffiti, vandalism and shoplifting, and combined to create an index of antisocial behaviours (possible range 0-5, higher score indicating engaging in higher number of antisocial behaviours).

Substance use

Study participants were asked whether they had ever tried smoking, alcohol, cannabis and any other drugs and if they had engaged in heavy drinking and weekly smoking. To create a combined substance use index score, measures of ever trying the following substances: tobacco, alcohol, cannabis or other drugs combined was created with a range of 0 (tried no substances) to 4 (used all substances). The study also investigated the extent of use with tobacco (weekly smoking) and alcohol (heavy drinking).

Health behaviours

The study includes measures of Body Mass Index (BMI) (derived from objectively measured height and weight as measured by interviewer), and weight perception (perceiving oneself as overweight).

Comparing the two cohorts

A key strength of this investigation is the use of two large contemporary cohorts with comparable measures – of mental ill-health, substance use, antisocial behaviours, weight and weight perception – available at the same age. It is important to note that one cohort, Children of the 90s, is a regional cohort and the Millennium Cohort Study is a national cohort. However, we account for differences in the composition of these cohorts in our analyses.

The Millennium Cohort Study (MCS) is following 19,517 young people born across the UK in 2000-02, building a uniquely detailed portrait of the children of the new century. The last survey of parents and children took place in 2018-19 when the study members were age 17. Data from the Age 17 Survey is now available. The MCS is funded by the Economic and Social Research Council and a consortium of government departments, and managed by the UCL Centre for Longitudinal Studies at the UCL Social Research Institute. Visit

The UCL Centre for Longitudinal Studies (CLS) is a resource centre based at the UCL Social Research Institute. CLS is home to four national longitudinal cohort studies, which follow the lives of tens of thousands of people. The Centre is funded by the Economic and Social Research Council (ESRC).

The UCL Social Research Institute (SRI) is one of the leading centres in the UK for multidisciplinary teaching and research in the social sciences. Based at the UCL Institute of Education, and with more than 180 academic, research and professional staff, it works to advance knowledge and to inform policy in areas including gender, families, education, employment, migration, inequalities, health and child/adult wellbeing.

The Economic and Social Research Council (ESRC). The ESRC, which funds the UCL Centre for Longitudinal Studies, is part of UK Research and Innovation, a non-departmental public body funded by a grant-in-aid from the UK government. For more information visit

The ESRC is the UK’s largest funder of research on the social and economic questions facing us today. It supports the development and training of the UK’s future social scientists and also funds major studies that provide the infrastructure for research. ESRC-funded research informs policymakers and practitioners and helps make businesses, voluntary bodies and other organisations more effective.

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