Depression in transitional aged youth (TAY; aged ~16-24yr) has become a major issue of concern, with 14-25% of those aged 12-21yr experiencing at least one episode of depression. As such, the burden of disease of depression in this population is substantial. Depression in TAY is characterized as a chronic, relapsing disorder, with 50-70% of remitted patients developing a subsequent depressive episode within five years. Further, in younger adulthood (~21-38yr) individuals who experience depression do not always show complete functional recovery between episodes and report residual cognitive impairments. However, research examining the neural correlates of putative cognitive impairments in depressed individuals has traditionally focused on adult populations, with more limited research in depressed TAY. One means of characterizing neural profiles during cognitive processing is via electroencephalography (EEG), and event-related potentials (ERPs) extracted from EEG. To date, it is unclear if ERP profiles during tasks tapping into certain cognitive processes known to be altered in depressed adults are comparable in depressed TAY. Greater insight into the neural features of cognitive processes in the context of depression can, ultimately, help in refining intervention and perhaps prevention strategies in depressed youth.
The primary aim of this work was to assess ERP-indexed neural profiles of attention, including novelty orienting, and inhibition via the auditory oddball and visual flanker tasks in depressed, unmedicated TAY (DEP) vs. non-depressed TAY (HC). Specifically, the N2 and P3 ERPs elicited by incongruent and congruent stimuli in a visual flanker task were assessed, as were the P3a and P3b ERPs extracted from an auditory novelty oddball task. Further, behavioural scores on three tasks, measured by the National Institutes of Health (NIH) Toolbox, that tap into similar cognitive processes as the ERP tasks (i.e., executive function, stimulus evaluation, inhibition, and working memory) were compared between groups using well-validated cognitive tests. Finally, correlations were carried out on the entire sample’s cognition scores and ERP measures, as well as the DEP group’s clinical scores and ERP measures to explore the relation between behavioural and neural features.
A significant difference was found between groups for the early P3a (eP3a) latency elicited by unexpected novel sounds in the oddball task; the DEP group had a significantly shorter latency than the HC group. For the flanker task, group differences were found for N2 amplitude to incongruent flanker stimuli, wherein the DEP group showed significantly higher amplitudes than the HC group. No group differences were found between composite scores of three NIH Toolbox tasks assessed. Correlations revealed a positive relation between the Dimensional Change Card Sort test (NIH Card Sort task), generally regarded as a test of executive function, and P3 amplitude to both congruent and incongruent stimuli on the ERP Flanker task. Second, a positive relation existed between the Flanker Inhibitory Control and Attention task (NIH Flanker) and P3 latency on the ERP Flanker task.
This study failed to replicate previous reports of reduced ERP amplitudes and increased latencies of the oddball and flanker tasks in a depressed adult populations population. However, they contribute to our limited knowledge on the effects of depression in youth on cognitive processes and associated neuronal profiles. Indeed, the data suggest that non-severely depressed and unmedicated young people exhibited more efficient cortical processing to novelty orienting than matched controls, perhaps reflecting a hyper-vigilant state. Further, depressed TAY appeared to exhibit more pronounced cortical resource allocation to processes implicated in inhibition. Across all participants, we were also able to demonstrate a relation between better executive function and increased cortical resource allocation to attentive processes, and greater behavioural inhibition being associated with longer cortical processes of attention. Collectively, these data inform our understanding of the neural processes in young people with depression; such insight may aid in more refined intervention and prevention strategies in the future.
| Identifer | oai:union.ndltd.org:uottawa.ca/oai:ruor.uottawa.ca:10393/43302 |
| Date | 16 February 2022 |
| Creators | Staff, Corrine |
| Contributors | Jaworska, Natalia, Knott, Verner |
| Publisher | Université d'Ottawa / University of Ottawa |
| Source Sets | Université d’Ottawa |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | application/pdf |
| Rights | Attribution-NonCommercial-NoDerivatives 4.0 International, http://creativecommons.org/licenses/by-nc-nd/4.0/ |
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