Brain-Derived Neurotrophic Factor Val66Met Polymorphism Is Associated With a Reduced ERP Component Indexing Emotional Recollection.

Rhiannon Jones,Joydeep Bhattacharya,Gavin Craig

doi:10.3389/fpsyg.2019.01922

Abstract

The Met allele of the brain-derived neurotrophic factor (BDNF) Val66Met polymorphism is associated with reduced functioning of the amygdala and hippocampus. It has been linked to major psychiatric conditions, including depression and post-traumatic stress disorder, and is associated with deficits in episodic memory. The precise mechanisms of the BDNF gene’s influence on emotional memory are not well characterized, especially its impact on recognition. Two electrophysiological experiments of emotional memory were run on two independent samples genotyped for BDNF Val66Met. Event-related potentials (ERPs) corresponding to the recognition of negative and neutral words (Experiment 1, N = 37) and negative and positive words (Experiment 2, N = 23) were recorded, and the late parietal component (LPC), typically associated with conscious recollection, was analyzed. In Experiment 1, a reduced LPC was observed in Met carriers (N = 12) compared to Val homozygotes (N = 25) in the negative condition, but the group difference was not present in the neutral condition. In Experiment 2, the reduced LPC was seen in Met carriers (N = 12) compared to Val homozygotes (N = 11) across both conditions. This study provides the first evidence of an association between the BDNF Val66Met genotype and the late parietal electrophysiological component, suggesting that the conscious experience of emotional recollection may differ according to BDNF Val66Met genotype. Further, these results suggest that this effect is likely due to emotional arousal rather than valence polarity. Results were discussed with reference to the possible mechanisms by which emotional recollection deficits may contribute to psychopathology.

Highlights

A commonly found single nucleotide polymorphism (SNP) of the brain-derived neurotrophic factor (BDNF) gene has been strongly linked to both episodic memory and psychopathology
While the neural evidence doesn’t present a clear picture of whether we would expect emotional memory performance would be increased or decreased in Met carriers compared to Val homozygotes, the results of two studies which found performance differences suggests that it would be lowered
Based on the literature reviewed above, we predicted a significant difference between the event-related potentials (ERPs) response to correctly rejected new words compared to successfully remembered words occurring at 500–800 ms and maximal in posterior compared to frontal regions, consistent with the topography of the late parietal component (LPC). We hypothesized that this LPC difference would be significantly reduced in Met carriers compared to Val homozygotes, and we tentatively hypothesized that this reduction would be largest in response to emotional stimuli

Summary

Introduction

A commonly found single nucleotide polymorphism (SNP) of the brain-derived neurotrophic factor (BDNF) gene has been strongly linked to both episodic memory and psychopathology. This valine (Val) to methionine (Met) amino acid substitution at codon 66 (Val66Met) is associated with reduced hippocampal volume (e.g., Egan et al, 2003; Schofield et al, 2009), and behavioral. The Met allele is often linked to cognitive or neural differences within patient samples (Cao et al, 2016), or diminished therapeutic response (Felmingham et al, 2013; Notaras et al, 2015), suggesting that its role in psychopathology may be an indirect consequence of its role in cognitive functions such as memory and emotional processing. As evidence from combined ERP/fMRI (Hoppstädter et al, 2015) and patients with hippocampal lesions (Düzel et al, 2001; Addante et al, 2012) support the role of hippocampal networks in generation of the LPC but not the FN400, we strategically focused our analysis on the LPC amplitude

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