Teenage mental health not just about genes

The research team say the findings – which drew on nearly 10,000 teenagers in England and Wales and over 12,000 teenagers in Sweden - are important for understanding that there are a range of pathways through which teenagers might experience mental health problems. For some, it is more due to inherited predisposition and for others there is more of an environmental component. 

Lead researcher Professor Angelica Ronald, Professor of Psychology and Genetics, said: “Genetic research has accelerated rapidly for mental health conditions in recent years. There is still a tendency to think of mental health being influenced by either genes or environment, but we know that both play a role.  Adolescence is a particularly critical time because most mental health problems start around then. Our research is unique in the way it shows how genetic propensity and environmental adversity interact in their influence on adolescent mental health. We found that genetic influence played less of a role for some groups of teenagers, particularly those experiencing considerable environmental adversity.” 

To provide such evidence, Professor Ronald, at Birkbeck’s Centre for Brain and Cognitive Development, asked 10,000 16-year-olds across England and Wales about their mental health. The study focussed on symptoms such as paranoia, hallucinations and extreme lack of motivation. The teenagers and their parents reported on these symptoms and on a range of environmental adversities that the teenagers had experienced, which included being bullied and having stressful life events. The 16-year-olds were all twins who had enrolled in the study. By studying twins, the team were able to look at the role of inherited and environmental influences. To bolster the study, Professor Ronald’s team found the same pattern of results when they worked with a second sample of teenagers, this time based in Sweden.  

Professor Ronald states: “Clinicians have observed how some mental health problems seem to be triggered through environmental adversities and this can be in teenagers with no family history of mental health problems. For others, mental health problems seem to arise despite a lack of apparent environmental adversities, which might reflect a greater inherited component. I was keen to test if this was the case. 

“We found that the role of genetic influences for symptoms such as paranoia was lower in the teenagers who had experienced more environmental adversity. Whereas for teenagers with paranoia and with less environmental adversity, the inherited factors played a greater role. 

“What we need to know next is how to prevent and offer early support for mental health challenges in teenagers. It’s essential to understand why these problems are triggered and there might not be a one-size-fits-all answer for everyone. Finding out about the range of causes will enable more targeted approaches to preventing mental health problems and for supporting those teenagers who are experiencing them.” 

Co-investigator Professor Daniel Freeman, from the Department of Psychiatry at University of Oxford commented: “We know that mental health problems such as excessive mistrust in adolescents can be corrosive, generating anxiety and limiting interactions with friends. For a small proportion it can also be a precursor to further mental health difficulties. This study shines a fascinating light on the emergence of mistrust, showing the pathways that can tip people into difficulties. Excessive mistrust in adolescence is seldom discussed but could prove a pivotal focus in future preventative mental health initiatives.” 

This research was funded by the UK Medical Research Council with additional support from the US National Institutes of Health, MQ Mental Health Research and UK National Institute for Health Research.  

‘Heritability of Psychotic Experiences in Adolescents and Interaction with Environmental Risk’ was published in JAMA Psychiatry on 3 August and is freely available to read online.