In September 2017, Hurricane Maria – a powerful, category four storm – hit Puerto Rico, killing over 3,000 people in its immediate aftermath, knocking out power to almost all of the island’s 3.4 million inhabitants, and causing more than $100 billion in damages. New research led by Arizona State University suggests that the hurricane’s impact on people’s long-term health may have been more severe and insidious than previously thought.
By studying a population of rhesus macaque monkeys living since 1938 on the isolated Cayo Santiago Island near Puerto Rico – which has also been severely hit by the hurricane – the scientists found that exposure to such intense levels of stress and adversity has accelerated some of the primates’ aging processes, leading to lowered immunity and earlier onset of a variety of health issues. While studies on humans are yet to be performed, these results suggest that extreme events such as natural disasters may also have similar negative, long-term effects on people’s health.
“While everyone ages, we don’t all age at the same rate, and our lived experiences, both negative and positive, can alter this pace of aging. One negative life experience, surviving an extreme event, can lead to chronic inflammation and the early onset of some age-related diseases, like heart disease,” explained corresponding author Noah Snyder-Mackler, an assistant professor of Animal Behavior at Arizona State University’s School of Life Sciences. “But we still don’t know exactly how these events get embedded in our bodies leading to negative health effects that may not show up until decades after the event itself.”
Although only 2.75 percent of the macaque population died in the immediate aftermath of the storm, and no difference in survival rates was noticed in the first year after the event, the scientists found that monkeys who lived through the hurricane had immune gene expression profiles that had aged two extra years, which is the equivalent of seven to eight years of human lifespan.
“Overall, cell-specific markers of canonical pro-inflammatory immune cells, such as CD14+ monocytes, had higher expression in older individuals and those that experienced the hurricane. Further, expression of helper T-cell genes, an anti-inflammatory cell type, decreased in older animals and those after the hurricane. Together, this possibly implicates more inflammatory activity in animals after storm, similar to what we see in older individuals,” explained Professor Snyder-Mackler.
Interestingly, not all monkeys responded in the same way to the hurricane. For instance, some monkeys’ biological ages increased much more than those of others. Scientists hypothesize that animals which had better support from their peers may have fared better in overcoming the storm’s detrimental effects. Further research is needed to investigate whether this hypothesis holds. Moreover, studies on humans are also necessary to clarify the relation between biological aging, adversity, and social structures in the face of natural disasters.
The study is published in the journal Proceedings of the Natural Academy of Sciences.