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Cognitive test can predict risk of mental illness in teenagers, say scientists

BMJ 2012; 345 doi: (Published 29 November 2012) Cite this as: BMJ 2012;345:e8109
  1. Krishna Chinthapalli
  1. 1BMJ

Adolescents with a particular genetic variant and a history of an abusive family life are worse at judging emotions and at an increased risk of developing depression and anxiety, says new research.1

The University of Cambridge psychiatrists who conducted the research interviewed 238 teenagers, then conducted cognitive tests and looked at variations in a gene for serotonin transport, 5-HTTLPR. A shorter variant of this gene, the SS allele, is present in 18% of the population and is known to increase the risk of depression in adults with a history of adverse social events, such as bullying or abuse.

The 15 to 18 year old study participants, who had no history of psychiatric disorder, were asked about their early childhood experiences. Those who had the SS allele of the 5-HTTLPR gene and who were exposed to constant parental arguments or violence were worse at judging words in a cognitive test. In the task they categorised words either as positive, such as “joyful”; neutral, such as “range”; or negative, such as “failure.” The researchers found that 16 teenagers with an SS allele and a history of adverse childhood events were significantly worse at judging the tone of neutral words than the other 222 participants (Cohen’s f2=0.33 (95% confidence interval 0 to 0.65); P=0.01).

Barbara Sahakian, one of the lead investigators, explained the importance of emotional judgments at a press conference to announce the release of the study. “The way we perceive and respond to emotions affects our resilience and whether we succumb to depression and other maladaptive ways of thinking,” she said.

Ian Goodyer, the study’s lead investigator, added, “The evidence is that both our genes and our early childhood experiences contribute to 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 authors hoped that emotional processing could be used to screen teenagers for the risk of psychiatric disorders. Sahakian said that “75% of mental illnesses start before the age of 24 years, so it is really important that we look at these people before they have a breakdown or before they have an episode of depression.”

The study’s limitations were acknowledged by the coauthor Matthew Owens. The sample was too small to allow the researchers to look at the severity of family discord in early life. And he admitted that the findings did not directly link psychiatric disorders themselves to emotional processing or to variants in the 5-HTTLPR gene.

The researchers are now prospectively following adolescents to look at the incidence of mental illness and are also recruiting to a larger study to corroborate and explore these findings.


Cite this as: BMJ 2012;345:e8109


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