Some young adults who were bullied as a child could have a greater risk of ongoing depression due to a mix of genetic and environmental factors according to a new study from the University of Bristol.

Researchers wanted to find out what factors influenced depression in young adults between the ages of 10 and 24 and why some people responded differently to risk factors such as bullying, maternal postnatal depression, early childhood anxiety and domestic violence.

Using detailed mood and feelings questionnaires and genetic information from 3,325 teenagers who are part of Bristol’s Children of the 90s study, alongside evidence of these risk factors at nine points in time they found that childhood bullying was strongly associated with trajectories of depression that rise at an early age. Children who continued to show high depression into adulthood were also more likely to have genetic liability for depression and a mother with postnatal depression. However, Children who were bullied but did not have any genetic liability for depression showed much lower depressive symptoms as they become young adults.

University of Bristol PhD student Alex Kwong commented:

“Although we know that depression can strike first during the teenage years we didn’t know how risk factors influenced change over time. Thanks to the Children of the 90s study, we were able to examine at multiple time points the relationships between the strongest risk factors such as bullying and maternal depression, as well as factors such as genetic liability.

“It’s important that we know if some children are more at risk of depression long after any childhood bullying has occurred. Our study found that young adults who were bullied as children were eight times more likely to experience depression that was limited to childhood. However, some children who were bullied showed greater patterns of depression that continued into adulthood and this group of children also showed genetic liability and family risk.

“However, just because an individual has genetic liability to depression does not mean they are destined to go on and have depression. There are a number of complex pathways that we still don’t fully understand and need to investigate further.

“The next steps should continue to look at both genetic and environmental risk factors to help untangle this complex relationship that would eventually help influence prevention and coping strategies for our health and education services.”

Lecturer in Psychiatric Epidemiology at the University of Bristol Dr Rebecca Pearson added:

“The results can help us to identify which groups of children are most likely to suffer ongoing symptoms of depression into adulthood and which children will recover across adolescence. For example, the results suggest that children with multiple risk factors (including family history and bullying) should be targeted for early intervention but that when risk factors such as bullying occur insolation, symptoms of depression may be less likely to persist”

Karen Black, Chief Executive Officer for Bristol’s Off the Record added:

“At Off The Record we see a diverse mix of young people presenting with a range of needs, often depression and anxiety. Understanding some of the factors that influence this will further help us to shape services and our offer for young people. I would also hope that studies such as these will help change policy direction and spending so that we start to get upstream of the issues that we know affect mental health including education and family, prevention rather than cure ideally.”

Paper: Genetic and environmental risk factors associated with different trajectories of depression symptoms from adolescence to young adulthood by Alex Kwong et al in JAMA Open Network