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Title: Neurocognitive function in adults depressed during the school age years
Author: Hewson, R. M.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2007
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This study was designed to investigate the theory of glucocorticoids mediated neurotoxicity as an explanation for anatomical changes and the likelihood of depressive recurrence in a group of recovered young adults. The study examines the changes in levels of the hormones cortisol and dehydroepiandrosterone (DHEA) between the first episode of depression and present day. It also investigates cognitive ability in tasks of memory ability and affect bias, and explores the functional processes associated with these tasks using functional Magnetic Resonance Imaging (fMRI). Anatomical correlates of these cognitive processes were examined using MRI, specifically the hippocampus and the amygdala. fMRI, MRI and cognitive task results were correlated with cortisol and DHEA levels and the length of previous illness. Results suggest that cortisol and DHEA return to similar levels as controls in recovery, and that DHEA levels at the first episode of depression may predict the length and severity of the illness. Although there is no significant difference in cognitive ability between the recovered participants and controls, those with a history of depression do show altered patterns of activation when performing tasks of memory encoding and retrieval and implicit affect recognition. In addition, there are significant positive correlations between hippocampal activation whilst encoding memories and cortisol levels at the first episode, and negative correlations of hippocampal grey matter density and the length of illness. Results also suggest that high levels of cortisol during episodes of depression result in damage to the hippocampus. Subsequently, in recovery, the “damaged” hippocampus requires greater activation to successfully encode memories in order to compensate for the loss of grey matter.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available