Abstract
The current study aims to explore the functional changes of the amygdala in patients with euthymic Bipolar Disorder (BD) using resting state fMRI (rs-fMRI). Twenty-one euthymic patients with bipolar disorder and 28 healthy controls participated in this study. Two of the euthymic patients with BD and three of the healthy controls were excluded due to excessive head motion. We found that patients with euthymia (38.79 ± 12.03) show higher fALFF (fractional Amplitude of low-frequency fluctuation) value of the amygdala (t = 2.076, P = 0.044), and lower functional connectivity between the amygdala and supplementary motor area (p < 0.01, GRF corrected) than healthy controls (33.40 ± 8.21). However, euthymic patients did not show a differential activity in ReHo (Regional Homogeneity) and gray matter of the amygdala region as compared to healthy controls. Thus, despite the absence of clinical symptoms in euthymic patients with BD, the amygdala functional activity and its connectivity to other brain regions remain altered. Further investigation of negative emotions and social functioning in euthymic patients with BD are needed and can help pave the way for a better understanding of BD psychopathology.
Highlights
Bipolar disorder (BD) is a chronic psychiatric disorder that is characterized by recurring manic or hypomanic episodes and additional episodes of depression usually separated by periods of euthymia [1]
We found that fALFF scores were significantly higher in the amygdala region in patients with euthymia as compared to healthy controls (HCs) group (t = 2.076, P = 0.044) during resting state
We found that the functional connectivity between the amygdala, bilateral supplementary motor area (SMA), and left Paracentral lobule is significantly lower in patients than in HCs (Table 3 and Figure 1)
Summary
Bipolar disorder (BD) is a chronic psychiatric disorder that is characterized by recurring manic or hypomanic episodes and additional episodes of depression usually separated by periods of euthymia [1]. A large body of evidence implicates dysfunction in brain networks related to emotion regulation in BD [5]. A common theory is that these patients show a hypoactivation in areas related to topdown control (such as the ventrolateral prefrontal cortex), and a hyperactivation in areas related to affective salience (such as the amygdala) [6]. This imbalance between the two systems can lead to episodes of mania and depression. BD is consistently associated with deficiency in the amygdala activity and in global network communication across several brain regions [7].
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