Hypertension may damage brain before rise in BP: Study

Hypertension may start damaging the brain long before doctors can detect any rise in blood pressure, a new study has found.

Researchers at Weill Cornell Medical College in New York reported that key brain cells linked to thinking and memory show early signs of stress within just three days of exposure to angiotensin II, a hormone involved in human hypertension.

The study, published in the journal Neuron on November 14, helps explain why hypertension is a major cause of cognitive decline and why many blood pressure medicines do not prevent brain problems.

In the study, scientists induced hypertension in mice and examined their brains at two stages - day three, when blood pressure was still normal, and day 42, when hypertension and memory issues became visible. On day three, they found major changes inside brain cells. Endothelial cells, which line blood vessels, showed early aging. Interneurons, which help balance brain activity, showed signs of dysfunction. Oligodendrocytes, which make the protective coating around nerves, could not switch on important maintenance genes. These changes appeared even before blood pressure went up, suggesting that hypertension affects the brain through pathways beyond blood flow.

Researchers also observed that the blood-brain barrier, which protects the brain from harmful substances, started weakening at this early stage. By day 42, the damage had worsened. The mice showed reduced myelin, slower signal transmission in brain circuits and signs of energy loss in neurons. These changes matched the cognitive decline seen in long-term hypertension.

The study tested the drug losartan, a common blood pressure medicine that blocks the angiotensin receptor. Losartan was able to reverse some of the early brain-cell damage in the mouse model.

Earlier, human studies have also shown that this class of drugs may offer better protection for the brain compared to other blood pressure medicines. However, the researchers emphasised that controlling blood pressure is important. Hypertension can damage the heart, kidneys and other organs.

The research team is now studying how early aging in small blood vessels may lead to further problems in brain cells.

Their goal is to develop treatments that can prevent or reverse cognitive decline linked to hypertension. The findings offer new insight into how brain damage begins at a very early stage and suggest that future therapies may need to target more than just blood pressure.