Scientists have discovered a cognitive biomarker for young adolescents who are at high risk of developing depression and anxiety. Researchers at the University of Cambridge say the marker is a variation of one gene—the short form of the serotonin transporter gene 5-HTTLPR.

For the study, 238 15–18-year-old participants underwent genetic testing and environmental assessment. The adolescents were then given a computer test to gauge how they process emotional information. The test had the participants evaluate whether words were positive, negative, or neutral (examples included “joyful” for positive, “failure” for negative, and “range” for neutral).

Those adolescents who were both homozygous for the short allele of 5-HTTLPR, as well as who had exposure to intermittent family arguments for longer than six months and violence between parents before the age of six, were shown to have marked difficulty in evaluating the emotion within the words, indicating an inability to process emotional information. Previous research has associated a maladjusted perception and response to emotions with a significantly increased risk of depression and anxiety. The authors concluded that cognitive and emotional processing deficits may act as an intermediate marker for anxiety and depressive disorders in genetically susceptible individuals exposed to early childhood adversities.

The scientists say the test for the cognitive biomarker, which can be done on a computer, could be used as an inexpensive tool to screen adolescents for common emotional mental illnesses. As the cognitive biomarker may appear prior to the symptoms of depression and anxiety, early intervention could then be initiated. The study, titled “5-HTTLPR and Early Childhood Adversities Moderate Cognitive and Emotional Processing in Adolescence”, was published yesterday in the journal PLoS One.

“Whether we succumb to anxiety and depression depends in part on our tendencies to think well or poorly of ourselves at troubled times,” says professor Ian Goodyer, principal investigator on the study. “How it comes about that some people see the ‘glass half full’ and think positively whereas other see the ‘glass half empty’ and think negatively about themselves at times of stress is not known.

“The evidence is that both our genes and our early childhood experiences contribute to such personal thinking styles. Before there are any clinical symptoms of depression or anxiety, this test reveals a deficient ability to efficiently and effectively perceive emotion processes in some teenagers—a biomarker for low resilience which may lead to mental illnesses.”

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