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About 35 million adults in the U.S. may develop high blood pressure because of negative events that happened to them during childhood. Researchers are exploring how an event you experience when you’re a kid can cause high blood pressure as an adult.

About 35 million children in the U.S. experience early-life stress (ELS). ELS is any traumatic event that occurs for an extended period of time to a child younger than 10. These experiences may range from emotional, sexual or physical abuse to parental divorce or growing up in a low-income household. ELS often has negative health effects—including high blood pressure—throughout a person’s adult life.

High blood pressure occurs when the force of the blood passing through the blood vessels remains higher than normal. If the pressure is not controlled, the blood vessels become stiff over time, which reduces blood flow and oxygen to the heart and increases the risk of heart failure or heart attack. High blood pressure can also cause severe damage to blood vessels in the kidneys and may eventually lead to chronic kidney disease, a condition in which the kidneys are no longer able to filter blood to remove toxic waste from the body. People with severe chronic kidney disease require a treatment called dialysis to keep them alive. During dialysis, a machine removes waste and excess water from the blood, effectively acting as an artificial kidney outside the body.

Because of these potential complications, it’s important to understand how ELS puts people at risk for high blood pressure. Numerous studies have shown that activation of immune cells can make high blood pressure worse. A recent study explored how ELS affects the immune system in rat kidneys, the organs responsible for long-term blood pressure control. The study found that rats exposed to ELS had higher numbers of immune cell markers and more immune cell activation in their adult life. Prolonged immune cell activation can prevent the kidneys from working properly, which may cause high blood pressure later on.

Interestingly, the study also found that when the immune cells in the kidneys of ELS rats were stimulated they showed that the immune cells were overactive. This finding is important because it shows researchers are starting to understand more about the link between ELS and high blood pressure. However, more research is needed to fully establish a connection between childhood trauma, the immune response of the kidneys and high blood pressure in adulthood.

Ijeoma Obi, MS, is a PhD candidate in the University of Alabama at Birmingham’s Department of Medicine, Nephrology Division, Section of Cardio-Renal Physiology and Medicine.