Living at the bottom of society, but also as a subordinate party in an unhealthy, intimate relationship, means living with chronic stress. And that stress, we now know from studies and statistics, shortens the lifespan. How exactly? That is not yet well known. Biologists from the University of Minnesota published an animal study in Aging Cell that provides some clarity.
The researchers put male lab mice together and observed their interaction. As with humans, some lab mice are ‘losers’ who typically draw the shortest straw in interactions, and some are ‘winners’ who know how to work themselves up in the hierarchy.
When the researchers had identified the real losers and winners, they put together pairs. Each pair consisted of a ‘loser’ [subordinate] and a ‘winner’ [dominant] mouse. The mice could see, smell and hear each other, but were separated from each other by a barrier.
The mere presence of a dominant mouse induces stress in a non-dominant mouse. This allowed the researchers to imitate the effect of life-long stress.
Then the researchers looked at how old the mice could become.
The subordinate mice lived shorter than the dominant mice.
When the researchers studied important blood vessels at the heart of the mice under the microscope, they saw more signs of arteriosclerosis in subordinate mice than in the dominant animals.
At the same time, the researchers found scar tissue in the heart muscle of the subordinate mice, and hardly in the dominant animals. This means that the heart of subordinate mice ages faster.
The researchers found inflammation markers at numerous sites in the body of the subordinate mice. In addition, the subordinate mice made more stress hormones.
Is has been known for years that, even in rich countries, people at the bottom of the social ladder live shorter lives and become ill more often than people in the higher social echelons. “Paradoxically this phenomenon has been known and established in many landmark studies about the negative impact of chronic stress and low socioeconomic status on human health”, research leader Alessandro Bartolomucci says in a press release. [sciencedaily.com May 29, 2018]
“But because this has never been replicated in any animal model, the mechanism of the association between stress, aging, and survival remains unclear. That’s where our study comes in.”