Faculty Bibliography

OBJECTIVE: We sought to characterize relationships between sluggish cognitive tempo (SCT) and both internalizing symptoms and executive functioning in adults with ADHD. METHOD: A total of 102 adults with ADHD completed clinical interviews and clinical rating scales. Hierarchical regression analyses were conducted to ascertain the independent predictive power of SCT symptoms for deficits in executive function (EF) after considering severity of ADHD inattentive and hyperactive-impulsive symptoms and internalizing symptoms. RESULTS: SCT correlated with ADHD inattentive symptoms and dimensional measures of depression and anxiety but not with clinical diagnosis of depression or anxiety. SCT predicted EF deficits over and above the effects of internalizing and ADHD symptoms. This relationship between SCT and EF was limited to the subset of participants ( n = 48) receiving stimulant treatment. CONCLUSION: SCT in adults with ADHD is associated with internalizing symptoms, ADHD inattentive symptoms, and, independently, with EF deficits. Further research is needed to ascertain why this relationship occurred primarily in adults concurrently receiving stimulants.

Patients with anxiety disorders often experience a relapse in symptoms after exposure therapy. Similarly, threat responses acquired during Pavlovian threat conditioning often return after extinction learning. Accordingly, there is a need for alternative methods to persistently reduce threat responding. Studies in rodents have suggested that exercising behavioral control over an aversive stimulus can persistently diminish threat responses, and that these effects are mediated by the amygdala, ventromedial prefrontal cortex, and striatum. In this fMRI study, we attempted to translate these findings to humans. Subjects first underwent threat conditioning. We then contrasted two forms of safety learning: active avoidance, in which participants could prevent the shock through an action, and yoked extinction, with shock presentation matched to the active condition, but without instrumental control. The following day, we assessed subjects' threat responses (measured by skin conductance) to the conditioned stimuli without shock. Subjects next underwent threat conditioning with novel stimuli. Yoked extinction subjects showed an increase in conditioned response to stimuli from the previous day, but the active avoidance group did not. Additionally, active avoidance subjects showed reduced conditioned responding during novel threat conditioning, but the extinction group did not. We observed between-group differences in striatal BOLD responses to shock omission in Avoidance/Extinction. These findings suggest a differential role for the striatum in human active avoidance versus extinction learning, and indicate that active avoidance may be more effective than extinction in persistently diminishing threat responses.SIGNIFICANCE STATEMENT Extinguished threat responses often reemerge with time, highlighting the importance of identifying more enduring means of attenuation. We compared the effects of active avoidance learning and yoked extinction on threat responses in humans and contrasted the neural circuitry engaged by these two processes. Subjects who learned to prevent a shock through an action maintained low threat responses after safety learning and showed attenuated threat conditioning with novel stimuli, in contrast to those who underwent yoked extinction. The results suggest that experiences of active control over threat engage the striatum and promote a shift from expression of innate defensive responses toward more adaptive behavioral responses to threatening stimuli.