Greg Knowles
University of Birmingham, UK
Title: Structural brain correlates of adolescent risk-taking and peer influence susceptibility
Biography
Biography: Greg Knowles
Abstract
Statement of the Problem: Adolescence is characterised by an increased propensity to engage in risky behaviour, in part the result of a heightened susceptibility to peer influence. We aimed to investigate whether adolescent risk-taking and peer influence susceptibility (PIS) had any relation to brain structure.
Methodology: A sample of 27 healthy adolescents (15 males, 12 females; age 17-23 years) participated in this study. We adapted the Balloon Analogue Risk Task so that participants completed it twice alone and twice after exposure to peer encouragement. The alone condition objectively measured baseline risk-propensity. Taking the percentage difference between conditions formed an empirical index of PIS. Using voxel-based morphometry, we compared baseline risk-propensity and PIS scores to grey and white matter volumes in whole-brain multiple regression analyses.
Findings: We identified a statistically significant positive correlation between baseline risk-propensity and white matter volume of the right posterior cerebellar lobule VII (p<0.01, FWE-corrected). Secondly, PIS scores were associated with volumetric variations in the right precuneus, right ventrolateral prefrontal cortex (VLPFC) and left dorsolateral prefrontal cortex (DLPFC) (p<0.001, uncorrected).
Conclusion: Across late adolescence, cerebellar volumes decline through mechanisms like synaptic pruning. Considering this, our research suggests a link between reduced lobule VII structural maturity and increased risk-propensity. We remain in the early stages of learning about the cognitive cerebellum. However, functional topographical studies demonstrate the recruitment of lobule VII specifically during cognitively-demanding, rather than movement-orientated, tasks. Perhaps lobule VII immaturity hinders the engagement of cognitive resources in decision-making, causing less risk-averse behaviour. With regards to PIS analyses, our study is the first to empirically investigate its structural correlates. Existent fMRI research implicates the DLPFC, VLPFC and precuneus in social cognition. While we provide preliminary evidence for a specific association between these regions and PIS, larger studies are needed to elucidate their exact contribution to task performance.