Abnormal vestibular asymmetries in patients with major depression

Background and objectives: The precedents about the existence of bilateral modulatory neuronal pathways between vestibular nuclei and higher brain centers involved in mood regulation, plus previous reports of abnormal vestibular function in major depression, support the relevance of further investigation inquiring the role of the vestibular system in depression's physiopathology and vice versa. The aim of this investigation is to study the vestibular activity in major depression patients using the rotatory test technique. Methods: Totally 21 major depression subjects (average age 37.9 years) according to Diagnostic and Statistical Manual of Mental Disorders-V criterion, who scored 12 or more in the 21-item Hamilton Rating Scale for Depression (HRS-D21), and 20 control healthy subjects (average age 41.1 years) who scored less than 7 in the HRS-D21, were tested in the rotatory chair. The nystagmus (vestibular-ocular reflex consisting of ocular movements induced by the vestibular system), was registered by electronystagmography. For the quantification of right or left vestibular activity, we measured the nystagmus's slow phase velocity induced by right and leftward rotation of the chair correspondingly. Results: Depression group showed an asymmetric vestibular pattern of activity (right/left vestibular activity ratio = 0.77 ± 0.2), significantly different (P < 0.01) from healthy who presented symmetric vestibular function (right/left ratio = 1.1 ± 0.3). Conclusion: Major depressive patients show an abnormal pattern of vestibular activity with lower function at the right side compared to left. We discuss the meaning and the possible underlying physiopathologic mechanisms of this finding. Also, we raise the possibility to consider this particular kind of vestibular asymmetry as a potential biomarker of major depression. Trial registration: ClinicalTrials.gov identifier: NCT03421847.