Young adults, who were bullied as a child, are at significantly greater risk of depression due to a mix of genetic and environmental factors, a study has found. Using detailed mood and feelings questionnaires and genetic information from 3,325 teenagers who were part of Bristol's Children of the 90s study, researchers 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.
"Although we know that depression can strike first during the teenage years, we didn't know how risk factors influenced change over time," said Alex Kwong, a PhD student at University of Bristol in the UK.
"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," Kwong added.
The study, published in the journal JAMA Network Open, has 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, it said.
"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," Kwong said.
Rebecca Pearson, lecturer at the university, said 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," she said.