Conventional treatments for depression, such as pharmacological interventions, are often ineffective. Up to half of patients do not respond, resulting in a poor prognosis for depression. Therefore, treatment options can be invaluable for increasing rates of remission. It is generally assumed that aerobic exercise benefits affective state. However, exercise remains a controversial treatment, possibly due to inconsistent evidence and unknown mechanisms. It is hypothesised variable results (literature is conflicting) are due to/because of heterogeneity in exercise interventions and subjective reports of exercise and mood state. If a biomarker for depression can be identified, the effects of exercise on depression could be objectively assessed. Neuroimaging research has elucidated numerous biomarkers, but has had little benefit on the diagnosis, prognosis or treatment of depression. However, if research can identify which biomarkers respond to treatments, can stratify patients and which can predict response outcome, targets for new interventions can be developed. Therefore, this thesis first establishes the effect of ECT treatment on emotionally salient brain regions in MDD, establishing the basis of a treatment responsive biomarker and potential targets for other interventions. The same functional connectivity methods are then used to analyse the effects of a single bout of aerobic exercise in a healthy population. Similar reductions in functional connectivity were observed in brain structures relevant to depression, suggesting exercise might target relevant brain structures. Finally, using the same functional connectivity methods, a long-term aerobic exercise intervention is shown to reduce functional hyperconnectivity in mildly depressed participants compared to healthy controls. This supports two primary hypotheses: that hyperconnectivity may underlie depressive disorders, constituting a biomarker for depression; and that aerobic exercise is an effective treatment for milder forms of depression.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:737951 |
| Date | January 2017 |
| Creators | Parkinson, Joel T. |
| Publisher | University of Aberdeen |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=236195 |
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