Abstract
BACKGROUND: The amygdala, as a crucial brain region, plays a key role in processing emotions and cognitive information. Given that patients with major depressive disorder (MDD) and bipolar disorder II (BD II) experience cognitive impairments, accurate diagnosis becomes a vital research focus. Consequently, we conducted an in-depth investigation into the relationship between the static volume of the amygdala and cognitive functions, aiming to provide valuable insights for future research in this field. METHODS: We collected a total of 42 treatment-naive MDD patients, 38 BD II patients, and 46 healthy controls (HC) from the Third People's Hospital of Foshan. Using magnetic resonance imaging (MRI) and an automated segmentation tool, we extracted the structural volumes of the amygdala. Pearson correlation analyses were performed with scores from the 17-item Hamilton Depression Rating Scale (HAMD), the Hamilton Anxiety Rating Scale (HAMA), and the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). Finally, we compared clinical data, as well as volume changes in the amygdala, among MDD patients, BD patients, and HC. RESULTS: In terms of depression scores, MDD individuals experience more severe emotional distress than those with BD. Both MDD and BD II patients show significantly higher anxiety levels compared to the HC. BD II is linked to widespread cognitive deficits, indicating poorer cognitive performance compared to both MDD and HC. In MDD, there is an observed amygdala volume increase compared to the HC. Additionally, correlation analysis revealed that the left amygdala volume is significantly correlated with Delayed Memory (List Recall) (r = 0.234, p = 0.010) and Delayed Memory (Story Recall) (r = 0.215, p = 0.018) (after multiple Bonferroni correction). CONCLUSION: For medication-naïve individuals with MDD and BD II, we observed a correlation between amygdala volume and cognitive function. From this, changes in amygdala volume may help reflect cognitive impairment in patients during the acute phase.