Risk of teenage depression affected by genes

The risk of depression in adolescents exposed to negative family environments during their childhood is partly dependent on their genetic make-up, suggest researchers.

'Whether we succumb to anxiety and depression depends in part on our tendencies to think well or poorly of ourselves at troubled times. The evidence is that our genes and early childhood experiences contribute to such personal thinking styles', said Professor Ian Goodyer, who led the study at the University of Cambridge.

Researchers analysed the genetic make-up of over 200 teenage participants, specifically looking at a gene encoding the transporter for the brain chemical serotonin. The gene occurs in two forms, long and short, with each individual carrying two copies of the gene - one inherited from each parent.

In addition to the genetic background of the participants, a history of their exposure to family arguments was also collected. The teenagers were then asked to complete a series of computer tests designed to determine how well they could process emotional information.

Teenagers carrying two short copies of the gene, who had also been exposed to prolonged family disputes before the age of six, performed worse in the tests when compared to those carrying two long copies of the gene who had been also exposed to similar childhood adversity.

The inability to easily process emotions was suggested to indicate an increased chance of developing depression, however the results of the computer test were not assessed in this regard.

'We do not know how good a predictor this test is, but this study provides sufficient validity to test it in the field', says Professor Goodyer.

The research is preliminary and requires further investigation, but the authors hope it could lead to the development of an inexpensive screening test for depression and anxiety in children. In the UK four percent of children aged between five and 16 years have an emotional disorder such as depression or anxiety.

Lead author of the study Dr Matthew Owens, from the University of Cambridge, says: 'This research opens up the possibility of identifying individuals at greatest risk and helping them with techniques to process emotions more easily or training them to respond more adaptively to negative feedback'.

The study was published in PLOS One.