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Examines vestibular activity changes in bipolar disorder mood states, suggesting implications for understanding mood regulation.
*Corresponding author; e-mail; amsozaried@gmail.com Introduction: Bipolar disorder show cyclic changes of mood with characteristic sleep-wake, motor and hormonal circadian abnormalities, suggesting that suprachiasmatic nuclei dysfunctions should play a role on it physiopathology. Previous research on major depression showing right side vestibular hypo-activity suggests a functional relationship between mood and vestibular activity. In order to elucidate if this vestibular pattern is related or not with mood states, we studied vestibular activity in bipolar disorder patients during successive different mood states between mania and depression. Methods: We studied two bipolar disorder patients during successive depressive and manic states using electronystagmographic records after rotatory stimulation. Right and left Slow Phase Velocity (SPV) of nystagmus was calculated in order to quantify vestibular activity and right/left SPV ratio to appreciate differences in vestibular lateralization during depression and mania. Results: We recorded 4 episodes of depression and 4 of mania. Compared with healthy people, in depression we found a 41.6% decrease in right SPV, 16.7% increase in left SPV and during mania we found a 30.4% decrease in right SPV and a 37.6% decrease in left SPV. The mean right/left SPV ratio in depression was 0.7±0.1 (mean +SD, 4 records). This was significantly lower than the 1.40.1 found in manic phases (4 records) ( p < 0.05, Mann-Whitney test). Conclusion: Different patterns of vestibular dysfunctions were found in mania and in depression in bipolar disorder patients. Right side hypo-activity and left side hyper-activity were observed in depression, while asymmetric hypo-activity (less activity at left side than right) was observed during the manic states. During the depressive phase in bipolar disorder patients we found that the vestibular abnormal activity was similar to those of major depression patients previously studied by our group. There is a need to study the pathophysiologic meaning of these findings in order to understand the relationship between lateralized vestibular brain stem nuclei and mood states, and the mechanism underlying rapid changes in vestibular lateralization. Circadian rhythms of hormonal secretion and sleep-wake cycles also should be further studied during both mood states in order to ascertain the relation between lateralized vestibular abnormalities and suprachiasmatic nuclei function. Publication History Article published online: 16 June 2026 © 2009. Brazilian Sleep Academy. This is an open access article published by Thieme under the terms of the Creative Commons Attribution-NonDerivative-NonCommercial License, permitting copying and reproduction so long as the original work is given appropriate credit. Contents may not be used for commercial purposes, or adapted, remixed, transformed or built upon. (https://creativecommons.org/licenses/by-nc-nd/4.0/) Thieme Revinter Publicações Ltda. Rua Rego Freitas, 175, loja 1, República, São Paulo, SP, CEP 01220-010, Brazil
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Ried et al. (2009) studied this question.
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