The marker is a variation of a certain gene — the short form of the serotonin transporter gene 5-HTTLPR.
For the study, scientists at the University of Cambridge recruited 238 teens (ages 15 to 18) to receive genetic testing and an environmental assessment.
The participants were then given a computer test to determine how they process emotional information. The teens had to decide whether words were positive, negative, or neutral (examples included “joyful” for positive, “failure” for negative, and “range” for neutral).
Those teens who were both homozygous for the short allele of 5-HTTLPR had significant difficulty evaluating the emotion within the words, suggesting an inability to process emotional information.
These same teens also had exposure to sporadic family arguments for over six months and witnessed violence between parents before the age of six.
Prior research has linked a disturbed perception and response to emotions with a much greater risk of depression and anxiety.
The researchers concluded that cognitive and emotional processing problems may be an intermediate marker for anxiety and depression in genetically susceptible individuals exposed to early childhood adversities.
The scientists say the test, which can be done on a computer, could be used as an inexpensive tool to screen teens for common mental disorders. As the cognitive biomarker may appear before the symptoms of depression and anxiety, early intervention could then be initiated.
“Whether we succumb to anxiety and depression depends in part on our tendencies to think well or poorly of ourselves at troubled times,” said Ian Goodyer, M.D., 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.”
The study is published in the journal PLoS One.
Source: University of Cambridge