There is a strong negative correlation between depressive symptoms and amygdala nuclei, suggesting that volumetric reductions may be linked to worsening depression symptomatology, according to study data published in Scientific Report.
Patients with major depressive disorder (MDD) (n=24) and age-matched control individuals (n=20) underwent structural magnetic resonance imaging (MRI) at 7 T field strength. The Montgomery-Asberg Depression Rating Scale was used to capture depressive symptomatology in all participants. For analysis, the whole amygdala was segmented into subnuclei and the whole hippocampus was segmented into subfields. Amygdala nuclei and hippocampal subfield volumes were normalized to intracranial volume. Between-group volumetric analyses were performed using 2-tailed independent t-tests adjusted for age and sex. Linear regression analyses were conducted in the patient group to identify associations between brain volumetrics and depressive symptoms.
The mean ages of patients and control individuals were 39.6 (standard deviation, 10.4) and 39.5 (standard deviation, 12.5) years, respectively. The majority of participants were men, comprising 62.5% of patients and 75.0% of control individuals. After adjusting for age and sex, no significant between-group differences were identified in amygdala nuclei and hippocampal subfield volumes. Among patients, volumes of the amygdala right lateral nucleus (P =.050), left cortical nucleus (P =.032), and the right and left hemispheres of the bilateral corticoamygdaloid transition area (both P =.032) were negatively associated with Montgomery-Asberg Depression Rating Scale score. When grouped, the right basolateral complex (P =.050) and the right and left hemispheres of the centrocortical complex (both P =.032) were also negatively associated with depression severity.
The right accessory basal nucleus and right basal nucleus also correlated with depression severity, although these findings did not remain significant after adjustments for age and sex. After correction for false discovery, negative correlation between MDD severity and the volume of the right CA1 and CA 3/4 subfields was not significant.
“Using high-field strength MRI, we report the novel finding that MDD severity is consistently negatively associated with amygdala nuclei, linking volumetric reductions with worsening depressive symptoms,” the researchers concluded. Further study in a larger cohort is necessary to explore these findings.
Disclosure: Several study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.
Brown SSG, Rutland JW, Verma G, et al. Structural MRI at 7T reveals amygdala nuclei and hippocampal subfield volumetric association with major depressive disorder symptom severity. Sci Rep. 2019;9(1):10166.