Consequences of working under a horrible boss are undermining of confidence, loss of mental health and serious harm to health, according to an Ohio State University study.

Researchers found that chronic stress results in changes in the gene activity in immune cells. These changes cause the cells to be prepared to fight an infection or trauma that doesn't actually exist. This leads to inflammation in the body, which causes many health problems, including heart disease and diabetes.

Similar primed immune cells were notices in people living in poorer areas and chronically stressed people.

"The cells share many of the same characteristics in terms of their response to stress," said Dr John Sheridan, associate director of Ohio State University's Institute for Behavioural Medicine Research, and co-lead author of the study, in an official statement. "There is a stress-induced alteration in the bone marrow in both our mouse model and in chronically stressed humans that selects for a cell that's going to be pro-inflammatory."

"So what this suggests is that if you're working for a really bad boss over a long period of time, that experience may play out at the level of gene expression in your immune system."

For the study, Sheridan tested the stress levels in a group of male mice. He gave time to the mice to establish a hierarchy. Then he added an aggressive male to the group for two hours at a time. Conflicts arose and elicited  'fight or flight' responses in the resident mice as they were repeatedly defeated by the intruder.

'These mice are chronically in that state, so our research question is, "What happens when you stimulate the sympathetic nervous system over and over and over, or continuously?" We see deleterious consequences to that,' Sheridan said.

The research has been published in the journal Proceedings of the National Academy of Sciences.