Lookup NU author(s): Professor John O'Brien,
Dr David Cousins,
Dr Jonathan Richardson,
Professor Alan Thomas,
Professor Andrew Blamire
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Background: Late life depression is known to be associated with neuroimaging changes including frontal and temporal lobe atrophy, an increased prevalence of white matter lesions and functional changes in key areas subserving frontostriatal circuits. However, the precise nature of the neurobiological dysfunction and its relationship to key features of depression is unclear. Using resting state blood oxygen level dependent (BOLD) MR imaging, spontaneous low frequency fluctuations (SLFs) in signal occur at frequencies of less than 0.1 Hz. These SLFs are linked with anatomically and functionally plausible networks, thus showing functional connectivity between brain regions. These networks have been termed resting state networks and using this method a default load network has been described. Methods: We have investigated functional connectivity using resting BOLD in 34 older people (aged over 65), 17 with major depression and 17 similarly aged controls. Subjects were scanned on a 3T MR system and resting state fMRI scans collected using an EPI sequence with 128 volumes collected over 6.4 minutes. A seed region of interest (2x2 voxels) was placed in the head of left and right caudate nucleus and connectivity between this region and the rest of the brain analysed using tools within the FMRIB software library. Results: In depressed subjects connectivity with the caudate nucleus on both sides was present over a much wider area than the more limited and predominantly frontal connectivity seen in controls. Greater connectivity in depressed patients was found in parietal, frontal, subcortical (thalamus and basal ganglia) and limbic (cingulate) regions. Conclusions: This study supports the view that connectivity in mood regulating circuits is disrupted in late life depression. Resting BOLD is a non invasive method which requires no task dependent activation. It provides a novel way of undertaking repeated measurements to determine how functional neural circuit disruption is related to the onset and course of symptoms (both depressive and cognitive) in late life depression and has potential to provide valuable new insights into the neurobiology of illness and response to treatment.
Author(s): O'Brien JT, Kenny ER, Cousins D, Richardson J, Thomas A, Blamire A
Publication type: Conference Proceedings (inc. Abstract)
Publication status: Unknown
Conference Name: ICGP 8th Annual Scientific Meeting
Year of Conference: 2008