Abstract
Overgeneral autobiographical memory (AM) manifests in individuals with major depressive disorder (MDD) tested during depressed (dMDD) or remitted phases (rMDD), and healthy individuals at high-risk (HR) for developing MDD. The current study aimed to elucidate differences in hemodynamic correlates of AM recall between rMDDs, HRs, and controls (HCs) to identify neural changes following previous depressive episodes without the confound of current depressed mood. HCs, HRs, and unmedicated rMDDs (n = 20/group) underwent fMRI while recalling AMs in response to emotionally valenced cue words. HRs and rMDDs recalled fewer specific and more categorical AMs relative to HCs. During specific AM recall, HRs had increased activity relative to rMDDs and HCs in left ventrolateral prefrontal cortex (VLPFC) and lateral orbitofrontal cortex. During positive specific AM recall, HRs and HCs had increased activity relative to rMDDs in bilateral dorsomedial prefrontal cortex (DMPFC) and left precuneus. During negative specific AM recall HRs and HCs had increased activity in left VLPFC and right DMPFC, while rMDDs had increased activity relative to HRs and HCs in right DLPFC and precuneus. Differential recruitment of medial prefrontal regions implicated in emotional control suggests experiencing a depressive episode may consequently reduce one’s ability to regulate emotional responses during AM recall.
Highlights
It is a well established and replicated finding in the literature that patients with major depressive disorder (MDD), when compared to healthy controls, recall fewer specific autobiographical memories (AMs), and instead recall more overgeneral categorical autobiographical memory (AM) [1]
Recent functional magnetic resonance imaging studies in our laboratory demonstrated that currently depressed subjects [6], otherwise healthy individuals at high hereditary risk for MDD [5], and individuals remitted from MDD [7] all manifest differences relative to healthy controls (HCs) in the regional hemodynamic activity observed during specific AM
When comparing Example Generation to Riser Baseline, in the entire sample BOLD activity increased in left dorsolateral prefrontal cortex (DLPFC), posterior cingulate cortex (PCC), superior temporal and middle temporal gyrus, and bilateral dorsomedial prefrontal cortex (DMPFC) and parahippocampus/hippocampus
Summary
It is a well established and replicated finding in the literature that patients with major depressive disorder (MDD), when compared to healthy controls, recall fewer specific autobiographical memories (AMs), and instead recall more overgeneral categorical AMs [1]. This abnormality persists despite remission of depressive symptoms [2,3,4] and is present in individuals at high-risk (HR) for developing MDD based on having a first degree relative diagnosed with the disorder [5]. These findings suggest that AM recall constitutes a trait-like marker of MDD. A recent study by Hach et al (2014) found decreased hippocampal, as well as precuneus and posterior cingulate activation, and increased inferior frontal gyrus and frontal polar regions in dMDD participants relative to controls during specific AM recall [9]. Other studies examining AM recognition (as opposed to AM recall) in dMDD have found increased dorsolateral prefrontal cortex (DLPFC) activity during negative AM recognition [10,11], and increased activity in ventrolateral prefrontal cortex (VLPFC) during positive AM recognition [10] in dMDD relative to HC participants
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