Psychiatry - Theses
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ItemAn FMRI investigation of emotion regulation in youth depression( 2018)The ability to regulate emotions plays an important role in social development during adolescence and young adulthood. Further, impaired ability to regulate emotions using cognitive strategies is a hallmark feature of major depressive disorder. Currently, there is a limited understanding of the neural underpinnings of emotion regulation in young people and how cognitive forms of emotion regulation (like cognitive reappraisal) develop. This issue is particularly pertinent to improving our understanding of depression in young people, given that the period from adolescence to young adulthood is associated with substantial brain maturational changes in regions associated with emotion–regulation and it is a time when most first episodes of depression occur. In the present study, a cognitive reappraisal paradigm containing social–stimuli was designed to probe the neural correlates of emotion regulation in depressed youth: in particular, to determine whether there were differences in the way that depressed and control participants regulated social–affective material, as well as developmental effects observed within the two groups. tudy participants—a large group of 15– to 25–year–old depressed participants and a matched control group—underwent fMRI where they used cognitive strategies to reinterpret negative social imagery. As expected, this cognitive reappraisal paradigm robustly activated regions involved in cognitive control and social–affective processing in both groups. Among healthy 15– to 25–year–olds (Study One), younger participants exhibited greater activation of temporal and occipital brain regions during reappraisal—implicated in processing social material—in combination with weaker suppression of amygdala reactivity. Further analyses demonstrated that these age–related influences on amygdala reactivity were specifically mediated by activation of the fusiform face area. Study Two revealed that depressed youth were significantly less able to reduce negative affect during reappraisal (compared to healthy individuals), which corresponded to blunted modulation of amygdala activity. Depressed youth also showed heightened activation of the ventromedial prefrontal cortex (vmPFC) and reduced activation of the dorsal midline cortex. Further, as distinct from the healthy youth, there was no relationship between development and modulation of amygdala activation in the depressed group. As the largest study of reappraisal in a young sample to date, our results in healthy controls highlight the importance of activation changes in social–processing and emotion processing networks, as being crucial to potential differences in the ability for adolescents to regulate their emotions. Enhanced neural sensitivity to social stimuli (e.g., facial stimuli) in younger individuals suggests a sensitivity to emotions of others during reappraisal that may be both adaptive in facilitating learning, but might also suggest difficulty disengaging from aversive social–cues. Findings in depressed youth are consistent with those in adults which suggest depression–related disturbances in both extended medial prefrontal (‘generative’) as well as dorsal (‘regulatory’) systems that contribute to adaptive emotional processing. Excessive engagement of the vmPFC—a region emphasised in contemporary neural systems models of MDD— may, in particular, be central to understanding how the process of assigning a new meaning to negative emotional material may be altered in depressed youth, with implications for treatment.