Increased amygdala reactivity following early life stress: a potential resilience enhancer role

Tetsuya Yamamoto,Tomoya Matsumoto,Yasumasa Okamoto,Tsuneji Murakami,Greg J Siegle,Takashi Nakao,Shigeto Yamawaki,Go Okada,Shinpei Yoshimura,Hiroyuki Muranaka,Shigeru Toki,Yoshiyuki Takaishi,Masahiro Takamura,Yumiko Kaseda

doi:10.1186/s12888-017-1201-x

Abstract

BackgroundAmygdala hyper-reactivity is sometimes assumed to be a vulnerability factor that predates depression; however, in healthy people, who experience early life stress but do not become depressed, it may represent a resilience mechanism. We aimed to test these hypothesis examining whether increased amygdala activity in association with a history of early life stress (ELS) was negatively or positively associated with depressive symptoms and impact of negative life event stress in never-depressed adults.MethodsTwenty-four healthy participants completed an individually tailored negative mood induction task during functional magnetic resonance imaging (fMRI) assessment along with evaluation of ELS.ResultsMood change and amygdala reactivity were increased in never-depressed participants who reported ELS compared to participants who reported no ELS. Yet, increased amygdala reactivity lowered effects of ELS on depressive symptoms and negative life events stress. Amygdala reactivity also had positive functional connectivity with the bilateral DLPFC, motor cortex and striatum in people with ELS during sad memory recall.ConclusionsIncreased amygdala activity in those with ELS was associated with decreased symptoms and increased neural features, consistent with emotion regulation, suggesting that preservation of robust amygdala reactions may reflect a stress buffering or resilience enhancing factor against depression and negative stressful events.

Highlights

Amygdala hyper-reactivity is sometimes assumed to be a vulnerability factor that predates depression; in healthy people, who experience early life stress but do not become depressed, it may represent a resilience mechanism
Hyperreactivity is often associated with vulnerability to depression as it occurs in populations that tend to become depressed such as children with anxiety or depressed parents [5] as well as those at risk for depressive relapse [6], those with early life stress (ELS) [7], cognitively vulnerable individuals [8], and individuals with inhibited
To clarify the role of amygdala reactivity in resilience, we examined, using functional magnetic resonance imaging, whether increased amygdala activity downmodulated depressive symptoms and the impact of life events in individuals with a history of ELS but no history of depression

Summary

Introduction

Amygdala hyper-reactivity is sometimes assumed to be a vulnerability factor that predates depression; in healthy people, who experience early life stress but do not become depressed, it may represent a resilience mechanism. Effects of stress on the amygdala [12] are hypothesized to underlie alterations in cognition, mood, and behavior [13,14,15] These changes have been further hypothesized to shape individual differences in vulnerability for mood and anxiety disorder, Yamamoto et al BMC Psychiatry (2017) 17:27 such as emotional reactivity [16,17,18]. A great deal of data shows that early life stressors are associated with increased amygdala reactivity in the absence of psychiatric diagnoses [15]. This could represent vulnerability for future depression, or could suggest that neural adaptations to stress are protective

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