br Acknowledgments This study was funded by

Acknowledgments This study was funded by the NIH grant R21-MH080820 to J. R. Booth, and the Northwestern University Human CognitionT32-NS047987 NIH training grant to R. Hammer. Parts of the reported methods and findings are included in provisional patent NU2014-051-01 US. We thank Shira DeCovnick, Audrey Haque, Jessica Stroup and the other members of the Developmental Cognitive Neuroscience Lab at Northwestern University for their help in data collection, and Rupin Parikh for his help in data preprocessing. We also thank the participating children and their parents.
Over the adolescent period, teens spend increasingly less time under direct adult supervision (). Given this burgeoning independence, an essential ability to be learnt is self-regulation – a skill set that involves the cultivation of behavioural self-control, the capacity to cope with negative emotions, and the ability to maintain goal-directed behaviour (). Failure of self-regulation during the adolescent order ARQ 621 can lead to maladaptive behaviours such as excessive risk-taking, and poor mental health outcomes such as depression (). The dispositional trait of mindfulness, which reflects the tendency towards present-moment awareness, has been associated with positive psychological functioning, including enhanced self-regulation (). Based on the theoretical accounts introduced by , a two-construct model of dispositional mindfulness has been proposed, capturing individual differences in (1) attention and awareness and (2) acceptance and non-reactivity (). However, have suggested attention to the moment to be the single most critical construct of mindfulness, subsuming acceptance and non-reactivity. Higher levels of dispositional mindfulness are thought to facilitate self-regulation, because they are permissive of present-moment focussed states of consciousness that allow the mind to break free from maladaptive patterns of thinking and behaviour (). Further, dispositional mindfulness in adolescents has been shown to predict recovery from depression (). Higher levels of dispositional mindfulness have been measured as a positive outcome of mindfulness-based intervention (MBI) participation – which often involves mindfulness-based meditation practice (). However, given the complexity of such interventions, the exact mechanisms that produce this outcome are still not understood (). Given that dispositional mindfulness can be assessed as a trait within normal populations without specific training, including adolescent populations, research into the emergence of mindfulness over development provides an alternative perspective from which to investigate the mechanisms that determine dispositional mindfulness. The adolescent period is a unique time for the development of the brain, and specific patterns of maladaptive behaviour that reflect poor self-regulation during the adolescent period have been attributed to a normative imbalance between executive frontal and subcortical development. For example, risk-taking behaviours, such as dangerous driving, unsafe sex and drug abuse can have severe health consequences for teens (). “Dual systems” models of adolescent development have suggested that risk-taking behaviour becomes more prevalent when subcortical reward and affective systems such as the nucleus accumbens and amygdala develop quickly and early over the adolescent period, temporarily dominating the more slowly developing prefrontal executive systems (). The relative over-activity of the subcortical systems is thought to lead to increased sensation-seeking, impulsivity and emotional reactivity (). One of the ways in which mindfulness is theorized to aid self-regulation is via interactions that involve both frontal executive and subcortical brain systems. , for example, examined the link between mindfulness, executive function and subcortical brain region activity. Using a cross-sectional design, dispositional mindfulness was measured along with individual differences in neural response to affect-labelling during functional magnetic resonance imaging (fMRI). When other measures of psychological distress were controlled for, higher levels of dispositional mindfulness were associated with widespread PFC activation and left insula activation in synchrony with attenuated amygdala responses during affect-labelling. This apparent synergy between frontal cortical and subcortical regions was interpreted to reflect a potential neurobiological pathway through which higher levels of mindfulness could promote adaptation and improve frontal regulation of subcortical activity. However, without a longitudinal examination, such adaptive changes over time could not be confirmed. Further, this study was performed using a young adult, rather than an adolescent, sample, and analysis was restricted to fMRI.