Social stress harms the brains of low-status fish

Ever wondered how social stress affects our brains? Well, scientists are now diving deep, using the aquatic social dynamics of cichlid fish to peer into the murky waters of mental health.

The latest findings suggest that social dynamics can significantly influence oxidative stress in the brain. But what exactly is oxidative stress, and what’s the interplay with social stress?

Social stress and the brain

Social stress isn’t good for the grey matter in the brain. It’s believed to contribute to a build-up of oxidative stress in the brain.

This, in turn, has been linked to mental health and neurodegenerative disorders. However, the specific mechanisms that transform social stress into oxidative stress, and how social status factors in, remain hazy.

Dr. Peter Dijkstra and his team at Central Michigan University chose to investigate these questions in an unexpected setting – a fish tank filled with cichlids, a type of highly social fish with a hierarchical group structure.

The findings? Social stress can magnify oxidative stress in the brains of low-status fish.

Low rank, high stress

“We found that low rank was generally linked to higher levels of oxidative stress in the brain,” said Dijkstra.

“The patterns of oxidative stress in the brain are likely influenced by social experience modulating cellular processes in the brain.”

Male cichlids live within a rigid, eye-catching social hierarchy. Dominant males are larger, more aggressive, and flashier than their subordinate counterparts, thanks to higher levels of androgen hormones.

Stress in social fish

Dominant males have territories to protect and females to woo. What’s more, hormones like androgens are known to increase due to social stress and correlate with changes in levels of oxidative stress across various organs.

The researchers then wondered how social stress impacts oxidative stress levels, given that the cichlids’ stressful social life was closely tied to their androgen levels.

Monitoring social stress levels in fish

The researchers set the stage for cichlids to interact freely in large tanks. They then recorded the cichlids’ behavior and soon found a stable hierarchy emerging between the fish.

They collected blood samples and examined the brains of the male fish, measuring markers of oxidative stress and antioxidant capacity in each brain division.

The researchers found that low-status fish evidenced higher levels of oxidative stress and lower antioxidant capacity than their high-ranking counterparts. Even though the alpha males showed higher oxidative stress levels in their blood, their brains seemed somehow better shielded.

Surprisingly, signs of reproductive activity associated with high status in these fish were linked to higher antioxidant levels and lower oxidative stress in the brain. This could be connected to their higher androgen levels, which can be neuroprotective in certain situations.

However, the researchers warn that the effects of status on oxidative stress are far from simple. When they looked at markers of oxidative DNA damage and antioxidant capacity in various brain divisions, they found that different markers reacted differently to the fish’s social status.

Social stress and modern society

Dr. Dijkstra highlights the relevance of their study for understanding how stress in our modern human societies can influence essential physiological functions.

“We compare ourselves to others continuously, and these problems are especially compounded by social media. But I would be hesitant to directly relate our findings to human societies,” he states.

He suggests that far more research is needed before making any connections between the findings of the cichlid study and the effect of stress on human societies.

Future research directions

The scientists caution that further targeted studies are necessary to comprehend the impact of the interplay between social stress and oxidative stress on specific brain regions.

“I think we just uncovered some interesting patterns across different divisions of the brain,” said Dijkstra. “The next step is to understand the regulation of oxidative stress better and how social stress influences this. This requires more rigorous experimental studies.“

Our understanding of how social stress influences our brains is currently woefully inadequate, so every study like this helps us navigate the unknown a bit better.

So, whether you’re a dominant alpha or feeling a tad subordinate, remember that we’re all swimming in the same stressful societal waters. The point is to keep swimming and discover how we can navigate these currents better.

The study is published in the journal Frontiers in Behavioral Neuroscience.

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