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Differential Prefrontal and Subcortical Circuitry Engagement During Encoding of Semantically Related Words in Patients with Late Life Depression

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posted on 29.07.2015, 00:00 authored by S. Weisenbach, M. T. Kassel, J. Rao, A. Weldon, E. T. Avery
Objective: Verbal memory difficulties are common among individuals with late-life depression (LLD), though there is limited knowledge about disruptions to underlying cerebral circuitry. The purpose of this study is to examine aberrations to cerebral networks implicated in encoding novel verbal semantic material among older adults with LLD. Methods: Twenty-four older adults with early-onset LLD and 23 non-depressed comparisons (NDC) participated in the study. Participants completed a word list-learning task while undergoing fMRI. Results: In the context of equivalent recall and recognition of words following scanning and similar hippocampal volumes, patients with LLD exhibited less activation in structures known to be relevant for new learning and memory, including hippocampus, parahippocampal gyrus, insula, and cingulate, relative to non-ill comparisons. An important region in which the LLD group displayed greater activation than the NDC group was in inferior frontal gyrus (IFG), an area involved in cognitive control and controlled semantic/phonological retrieval and analysis; this region may be critical for LLD patients to consolidate encoded words into memory. Conclusions: Functional irregularities found in LLD patients may reflect different modes of processing to-be-remembered information and/or early changes predictive of incipient cognitive decline. Future studies might consider mechanisms that could contribute to these functional differences, including HPA-axis functioning and vascular integrity, and utilize longitudinal designs in order to understand whether functional changes are predictive of incipient cognitive decline.


Conflicts of Interests and Source of Funding: This research was supported by funding from the University of Michigan Depression Center (SLW, SAL), University of Michigan fMRI Laboratory (SLW, SAL), the Michigan Alzheimer’s Disease Research Center Pilot Grant Fund (SLW, SAL), and the National Alliance for Research on Schizophrenia and Depression (SAL).


Publisher Statement

This is the pre-peer reviewed version of the following article: Weisenbach, Sara L., et al. "Differential prefrontal and subcortical circuitry engagement during encoding of semantically related words in patients with late‐life depression." International journal of geriatric psychiatry 29.11 (2014): 1104-1115, which has been published in final form at DOI: 10.1002/gps.4165.


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