Faculty Bibliography

Distress intolerance (DI), the inability to tolerate stressful experiences, has been linked to multiple psychiatric conditions and maladaptive coping patterns. Although DI is often considered a trait-like variable, evidence indicates that self-report and behavioral indices of DI can be manipulated by contextual factors. Understanding such contextual influences is important given evidence of unexpected variability in these presumed trait-like measures over brief intervals. The current study examined the influence of context (manipulated by priming concepts of "Interminability" and "Brevity") in predicting behavioral persistence, in relation to self-reported DI. Results indicated that priming Brevity was associated with terminating a cold-pressor task more quickly. Self-reported DI was linked to earlier termination, but there was no interaction between self-reported DI and priming condition. Results indicate that contextual cues modulate performance on behavioral measures of DI. Hence, models of DI should consider both trait-like and contextual factors in understanding variability in DI measures.

Consistent evidence indicates that exercise improves cognition and mood, with preliminary evidence suggesting that brain-derived neurotrophic factor (BDNF) may mediate these effects. The aim of the current meta-analysis was to provide an estimate of the strength of the association between exercise and increased BDNF levels in humans across multiple exercise paradigms. We conducted a meta-analysis of 29 studies (N = 1111 participants) examining the effect of exercise on BDNF levels in three exercise paradigms: (1) a single session of exercise, (2) a session of exercise following a program of regular exercise, and (3) resting BDNF levels following a program of regular exercise. Moderators of this effect were also examined. Results demonstrated a moderate effect size for increases in BDNF following a single session of exercise (Hedges' g = 0.46, p < 0.001). Further, regular exercise intensified the effect of a session of exercise on BDNF levels (Hedges' g = 0.59, p = 0.02). Finally, results indicated a small effect of regular exercise on resting BDNF levels (Hedges' g = 0.27, p = 0.005). When analyzing results across paradigms, sex significantly moderated the effect of exercise on BDNF levels, such that studies with more women showed less BDNF change resulting from exercise. Effect size analysis supports the role of exercise as a strategy for enhancing BDNF activity in humans, but indicates that the magnitude of these effects may be lower in females relative to males.

OBJECTIVE:Poor threat-safety discrimination reflects prefrontal cortex dysfunction in adult anxiety disorders. While adolescent anxiety disorders are impairing and predict high risk for adult anxiety disorders, the neural correlates of threat-safety discrimination have not been investigated in this population. The authors compared prefrontal cortex function in anxious and healthy adolescents and adults following conditioning and extinction, processes requiring threat-safety learning. METHOD/METHODS:Anxious and healthy adolescents and adults (N=114) completed fear conditioning and extinction in the clinic. The conditioned stimuli (CS+) were neutral faces, paired with an aversive scream. Physiological and subjective data were acquired. Three weeks later, 82 participants viewed the CS+ and morphed images resembling the CS+ in an MRI scanner. During scanning, participants made difficult threat-safety discriminations while appraising threat and explicit memory of the CS+. RESULTS:During conditioning and extinction, the anxious groups reported more fear than the healthy groups, but the anxious adolescent and adult groups did not differ on physiological measures. During imaging, both anxious adolescents and adults exhibited lower activation in the subgenual anterior cingulate cortex than their healthy counterparts, specifically when appraising threat. Compared with their age-matched counterpart groups, anxious adults exhibited reduced activation in the ventromedial prefrontal cortex when appraising threat, whereas anxious adolescents exhibited a U-shaped pattern of activation, with greater activation in response to the most extreme CS+ and CS-. CONCLUSIONS:Two regions of the prefrontal cortex are involved in anxiety disorders. Reduced subgenual anterior cingulate cortex engagement is a shared feature in adult and adolescent anxiety disorders, but ventromedial prefrontal cortex dysfunction is age-specific. The unique U-shaped pattern of activation in the ventromedial prefrontal cortex in many anxious adolescents may reflect heightened sensitivity to threat and safety conditions. How variations in the pattern relate to later risk for adult illness remains to be determined.