Social defeat and the brain: new study reveals additional effects of stress.

We’ve long known that stress has negative consequences in regard to our health and is especially deleterious for our brains. Findings from a recently published study now point to the impact of additional effects as it relates to chronic stress or “social defeat,” which is a concept used in the study of the physiological and behavioral effects of hostile interactions among subjects (that can be animal or human models).

In this particular referenced study using laboratory mice that also drew upon the results of previous research, scientists examined the biological links between chronic social defeat (CSD) and affective disorders including the impact on areas of the brain associated with aging, depression, anxiety and other neurological conditions.

Research findings indicated that “CSD stress produces anxiety-like and depressive-like behavioral declines in susceptible mice; recovery after CSD cessation was marked by recruitment of leukocytes perhaps participating in vascular repair. The data suggest that co-morbidity of affective disorders and vascular diseases may be attributed in part to a common link in altered endothelial cell function.”

This points to several significant study highlights:

1.  Chronic social defeat caused behavioral deficits and blood-brain barrier breaks.
2.  Breaks showed tiny bleeds, fibrinogen deposition, and angiogenesis markers.
3.  Brain endothelial cells were isolated for analysis at gene transcriptional level.
4.  Stressed endothelial cells engaged vascular injury, growth, and repair programs.
5.  These repair programs are also seen in hypertension, cardiovascular disease, and aging.

Additionally, the study results identified the relationship between fibrinogen deposition in brain vasculature and declines in mood that suggest this fibrinogen entry provides an inflammatory signal that could transmit effects of CSD across the BBB. Fibrinogen in other disease states causes neuroinflammation, apparent as microglial activation; you can read more about the involvement of microglia in our blog, “What Causes our Body to Attack the Mind.”

We know too from the Global Burden of Disease Study (2017 data) that “major depressive disorder and related psychopathologies are a leading cause of disability in the world.” This longtime study has since 1990 provided comprehensive worldwide observational epidemiological data including mortality and morbidity from major diseases, injuries and risk factors to health at global, national and regional levels. By examining trends and making comparisons across populations, as well as looking at historical data, researchers are afforded the most in-depth understanding of the changing health challenges facing people across the world today.

It is imperative that we focus on employing science in identifying the root causes of multiple conditions, both chronic and acute, to fully understand the path to appropriate interventions –we must understand the cause of any condition and not just treat the symptoms. Integrative medicine affords us with this opportunity as well as the perspective to consider the best means and the methods to continue to offer the most hope for more patients.

In health,
Dr. Suzanne Gazda

Additional references:

Global Burden of Disease Study
https://www.thelancet.com/gbd

Golden, S., Covington, H., Berton, O. et al. “A standardized protocol for repeated social defeat stress in mice.” Nature Protocols 6, 1183–1191 (2011). https://doi.org/10.1038/nprot.2011.361
https://www.nature.com/articles/nprot.2011.361