Nonverbal behaviors are associated with increased vagal activity in major depressive disorder: Implications for the polyvagal theory.

BACKGROUND: Major depressive disorder (MDD) is associated with impairments in nonverbal behaviors (NVBs) and vagal activity. The polyvagal theory proposes that vagal activity regulates heart rate and NVBs by modulating a common anatomically and neurophysiologically discrete social engagement system. However, the association between these putative endophenotypes has not yet been explored. We hypothesize that in MDD, NVBs indicating positive affects and social interest and those indicating negative feelings and social disinterest could be associated with different patterns of vagal activity. METHODS: For this cross-sectional study we recruited 50 antidepressant-free participants with moderate-to-severe MDD. Vagal activity was indexed by heart rate variability (HRV) measures, and positive and negative nonverbal behaviors (NVBs) by a validated ethogram. Associations between NVBs and HRV were explored by bivariate analyses and multivariable models were adjusted by age, gender, depression severity, and self-reported positive and negative affects. RESULTS: HRV measures indicative of higher vagal activity were positively correlated with positive NVBs exhibited during the clinical interview. Conversely, NVBs related to negative affects, low energy and social disinterest were not associated with HRV. LIMITATIONS: Absence of a control group. CONCLUSIONS: The findings highlight that the examined depression endophenotypes (nonverbal behaviors and vagal activity) are related, shedding light on MDD pathophysiology in the context of the polyvagal theory.

Investigation of associations between recurrence of major depressive disorder and spinal posture alignment: A quantitative cross-sectional study.

The aim of this study was to investigate associations between poor spinal posture and the recurrence of major depressive episodes and severity of symptoms in patients with major depressive disorder (MDD). This was a cross-sectional quantitative study of MDD patients. Outpatients were recruited from consecutive admissions at a mood disorders unit of a tertiary psychiatric hospital. Of 136 MDD patients, 72 (53 women, 19 men; mean age, 42.4±9.1years) met all the criteria and completed the study. Forty-one patients were classified with a recurrent episode (RE) of MDD and 31 with a single episode (SE). Quantitative assessments of postural deviations were made using photogrammetry, including kyphosis, shoulder protraction, and head inclination. The severity of depressive episodes was assessed using the Hamilton Depression Rating Scale. The diagnosis and classification of patients were performed according to DSM-IV-TR and SCID criteria. Multivariate analysis of variance indicated that the RE group had greater anterior head inclination (35.39; SD: 1.57), greater scapular abduction (1.69; SD: 0.93), and worse thoracic kyphosis (139.38; SD: 1.19) than the SE group (p<0.001 for all). Multivariate analysis of covariance showed an interaction between the severity of depressive symptoms and the degree of thoracic kyphosis (p=0.002). Recurrence of depressive episodes is associated with measures of postural misalignment.