Even a slight rise in blood pressure might shrink young brains

Hypertension may cause brain shrinkage.
Hypertension may cause brain shrinkage.

Young adults with blood pressure that's higher than normal, but not yet high blood pressure, are still more likely to have brain shrinkage than those with normal blood pressure, a new German study finds.

It's long been thought that high blood pressure takes decades to affect the brain.

A wide range of functions

However, the new findings show "that subtle changes in the brain's grey matter can be seen in young adults who have never been diagnosed with high blood pressure," said lead researcher Dr Arno Villringer. His team reported the finding in the journal Neurology.

Grey matter contains most of the brain's neurons, essential for a wide range of functions.

"More research should be done to investigate whether [early loss of grey matter] could increase the risk for stroke, dementia and other cerebrovascular diseases later in life," Villringer said in a journal news release. He's at the Max Planck Institute for Human Cognitive and Brain Sciences in Leipzig.

The new study involved 423 people in their 20s and 30s, average age 28. All underwent MRI brain scans and had at least one blood pressure reading.

While 41% were found to have normal blood pressure (less than 120/80 mmHg), 29% had blood pressure from 120/80 to 129/84; 19% had blood pressure from 130/85 to 139/89; and 11% had high blood pressure above 140/90 (high blood pressure).

Everyone with blood pressure above normal was more likely to have lower grey matter volume in a number of areas of the brain, including the brain's frontal and parietal lobes, the hippocampus (important to memory), amygdala (a centre for emotions) and thalamus, which functions in motor skills, sleep and sensory signalling.

Overall, grey matter volume decreased as blood pressure increased, the researchers said.

Stroke and dementia

Villringer stressed that the study couldn't prove that above-normal blood pressure was the direct cause of the lowering of grey matter levels. But the findings do suggest that "treating high blood pressure or maintaining lower blood pressure in early adulthood might be essential for preventing the cascade from silent brain changes with no symptoms to organ-damaging conditions such as stroke and dementia," he said.

Two US experts said the findings raise new questions.

"When do you treat blood pressure, and at what measurement?" said Dr Gayatri Devi, a neurologist who specialises in memory disorders at Lenox Hill Hospital in New York City.

Based on the German findings, "the answer appears to be as early as possible and at blood pressures over 120/80 mmHg, if you want to keep your brain as healthy as possible," he said.

Dr Guy Mintz directs cardiovascular health at Northwell Health's Sandra Atlas Bass Heart Hospital in Manhasset, New York. He called the findings "thought-provoking and a wake-up call" for any doctor who treats high blood pressure.

Lifestyle changes

"While elevated blood pressure is easy to diagnose, data from the National Health and Nutrition database continually demonstrate our shortcomings, with only about 40% of patients with high blood pressure controlled," Mintz noted.

He stressed that loss of the brain's grey matter is typically seen in older adults. That the new study observed this loss in young adults suggests that maintaining normal blood pressure "in early adulthood may be important for preventing subsequent brain disease as patients get older," Mintz said.

Just how that's accomplished is another issue.

Ideally, "control and effective treatment of high blood pressure begins with lifestyle changes including diet and exercise, rather than medications," Mintz said. "However, some patients will also require medication."

Villringer agreed, saying that further research could also help determine whether, when and how blood pressure above normal in young adults should be monitored and managed.

Image credit: iStock

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