Abstract
- Purpose: Adolescence is a time of dramatic changes in a range of behaviours, which occur in tandem with changes in brain structure and function. These coincide with the physiological changes of puberty, but little research has focussed on the possible contributing role of puberty. One important behaviour emerging in adolescence is the increased propensity to make risky decisions. A prominent theory to explain this increased propensity for risk is the ‘dual systems’ model (Casey et al., 2008), where risky decisions result from a dissociation in the timing of the maturation of the limbic system and the prefrontal cortex, both regions involved in risky decision-making. The limbic system (incorporating the ventral striatum) is hypothesised to mature relatively early in adolescence, and is thought to be related to pubertal maturation. In contrast, the prefrontal cortex is thought to undergo more protracted development throughout adolescence. This study explores how developmental changes in brain function when performing a risk-taking fMRI (functional Magnetic Resonance Imaging) task are related to puberty, independently of chronological age. - Methods: Forty-five male participants aged 13-14 years underwent fMRI scanning whilst performing a risk-taking task (BART task, adapted from Lejuez et al., 2002). In this age range, there is normal variability in pubertal development, with individuals being at all stages of puberty from pre-puberty to having completed puberty. In the BART task, participants had to decide whether to inflate a virtual balloon on a screen. Successful inflation of the balloon resulted in the opportunity to earn more money, but risked the balloon popping and the money being lost. Stopping allowed the participants to save the money towards their final earnings. Participants completed four six-minute runs of the task. Pubertal stage was assessed using self-report measures including a pictorial Tanner stage and the Pubertal Developmental Scale (Petersen et al., 1988). Salivary hormone levels were collected to measure levels of Testosterone, Oestradiol and DHEA. Participants also completed validated self-report questionnaires of risk-taking, impulsivity and sensation-seeking. - Results: The analysis focused on a main effect, across the entire group, of active decision-making compared to the control condition in regions including the prefrontal cortex and limbic system, which are known to be involved in risky decision-making. We also investigated whether this activation was differentially related to puberty across regions, using both group-wise and regression analyses. - Conclusions; This study investigated a role for puberty in the functional development of brain regions involved in risky decision-making in males, and further informs the usefulness of the dual systems model of risk taking during adolescence.
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