A pathway imbalance in the brain may explain why teenage girls are twice as likely to get depression than boys.
For the first time, research by King’s College London shows that a biological brain mechanism called the kynurenine pathway plays a role in the development of depression during teenage years.
This pathway is a series of chemical reactions that process tryptophan, an amino acid found in food.
When tryptophan breaks down it can either produce brain-protecting chemicals or brain-damaging chemicals.
Senior author Professor Valeria Mondelli, Clinical Professor of Psychoneuroimmunology at King’s said adolescence was a time when many changes occurred in the brain, but we still know little about the possible biological drivers for depression and how this might affect the difference between teenage boys and girls.
“During adolescence there are a wide range of social and individual factors that influence mental health and by identifying the biological pathways involved we hope we can help build a clearer picture of how we can help teenagers manage depression,” Prof Mondelli said.
The study monitored 150 teenagers from Brazil aged 14-16 for three years. The teenagers belonged to one of three groups – those with a low risk of depression, those with a high risk of depression, and those who had been diagnosed with depression.
The researchers found that females with a higher risk or with depression, had lower levels of brain-protecting chemicals.
The study also found those with higher levels of inflammatory markers in the body were linked to increased production of neurotoxic chemicals found in those at high-risk or with depression, but not in low-risk teenagers. This suggests that inflammation might drive the kynurenine pathway to produce neurotoxic chemicals and increase the risk of depression.
First author and Senior Research Associate at King’s Dr Naghmeh Nikkheslat said the study indicated that the measurement of chemicals involved in the kynurenine pathway could help identify those at risk of persistent depression.
“This insight could help develop more targeted support for teenagers with depression through interventions that work in a range of ways on the kynurenine pathway from medication to lifestyle changes such as diet and exercise,” Dr Nikkheslat said.
The study was published in Biological Psychiatry.
