Recent research has revealed a strong link between social status loss and depressive-like behaviours in both humans and animals. A study published in Cell explored this phenomenon using a novel, non-violent behavioural paradigm in mice, offering valuable insights into the neural mechanisms that underlie depression triggered by social status decline. This study is particularly relevant given the well-established association between downward social mobility and depression, which is known to increase the risk of mental health disorders three to fourfold in humans.
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The research demonstrated that forced loss of social status induces depressive-like behaviours in mice, behaviours that can be reversed if the individual regains its social status. This contrasts with natural loss, where mice do not exhibit the same depressive tendencies. The study further identified a key neural circuit involving the lateral hypothalamus (LH) and the lateral habenula (LHb), which was activated during forced loss, but not natural loss, of social rank. This circuit generates negative reward prediction errors (RPE), leading to the inhibition of the medial prefrontal cortex (mPFC), which controls social competitiveness. This neural inhibition reinforces behaviours associated with subordination and depressive states.
Figure 1 “Forced loss” paradigm induces a stable loss of social rank
The findings suggest that loss of social status, particularly when unexpected, activates brain circuits that not only generate depressive behaviours but also reinforce the subordinate state. This is particularly significant as it provides a mechanistic foundation for understanding how social dynamics influence mental health. The study’s results highlight the evolutionary conservation of these behaviours, as similar depressive responses have been observed in non-human primates, birds, and even fish, further underscoring the importance of social status in mental health across species.
These insights have potential implications for developing targeted interventions for depression caused by social status loss, suggesting that modulating the LH-LHb circuit could offer new therapeutic avenues. The study is a major step forward in understanding the biological basis of depression linked to social hierarchies, a phenomenon that affects millions worldwide.
Journal Article: Fan, Zhengxiao, et al. “Neural Mechanism Underlying Depressive-like State Associated with Social Status Loss.” Cell, 2023.
Summary by Faith Oluwamakinde
