Weaker gut instinct put teenagers at risky behaviours

Making a snap decision usually means following your initial reaction - going with your gut.

That intuitive feeling sprouts from part of the brain called the limbic system that affects emotion, behaviour and motivation.

But during adolescence, the limbic system connects and communicates with the rest of the brain differently than it does during adulthood - leaving many adolescents vulnerable to riskier behaviours, according to researchers from Duke University.

"We know adolescence is a time of profound social change. It is also a profound time for risk-taking - a time period when peer influence is more important," said Kevin LaBar, a professor in the Duke Center for Cognitive Neuroscience.

This is when we start establishing independent relationships with adults, and some of those relationships are going to be influenced by how trustworthy those people are.

"It is important in these relationships to evaluate who you can and cannot trust," he added.

The study examined this capability in adolescent girls, ages 10 to 20.

The research team enrolled 43 girls and showed each 34 pictures of adult faces in extremely fast (50-millisecond to 100-millisecond) glimpses while recording their reactions in real time using functional MRI (fMRI) brain scanning.

After each flash, the images were immediately scrambled to prevent the girls from developing any lasting visual memory of a face.

After each image, participants rated the face as very untrustworthy, untrustworthy, trustworthy or very trustworthy.

Based on the fMRI results, the components of the limbic system known as the amygdala (which evaluates negative emotions) and insula (which plays a role in gut-level decision making) were the most active for the faces participants rated as untrustworthy.

Among all ages, the right amygdala showed high levels of activity when presented with an untrustworthy face.

"These heightened responses for untrustworthiness suggest that during this time, girls this age are particularly sensitive to the facial features they feel are untrustworthy," LaBar noted.

Maybe, it is a post-pubertal hormone change that brings on the heightened response or maybe they are more motivated to scan for social threats during this period, the researchers observed.

This findings could help design prevention and treatment interventions for risky decision-making or help adolescents with mental illness.

The study was appeared in the journal Social Cognitive and Affective Neuroscience.