White matter lesions in the brain that are associated with stroke and dementia are commonly seen in people with unstable blood pressure, European investigators report.

Dr. Monique M. B. Breteler, at Erasmus Medical Center in Rotterdam, the Netherlands, and co-investigators assessed data on 1625 subjects who were participating in nine ongoing European studies and were 65 to 75 years old. Information about their blood pressure had been collected for 5 to 20 years.

The team performed MRI brain scans to look for lesions in the area around the ventricular spaces and in the subcortex, and these were classified as severe or not severe.

Compared with stable blood pressure levels over time, both decreases and increases in diastolic blood pressure - the lower reading - more than doubled risk of severe periventricular white matter lesions, the researchers report in the medical journal Hypertension.

“Increase in systolic (upper reading) blood pressure was associated with a higher prevalence of severe periventricular and subcortical white matter lesions,” they add.

The most severe lesions were associated with treated but uncontrolled high blood pressure. When the condition was either untreated or successfully controlled with treatment, the risk of brain lesions was comparable.

Breteler’s group suggests that long-standing high blood pressure may cause structural changes in the small blood vessels, leading to low perfusion of the brain.

The finding that risk is elevated even in people who are successfully treated suggests that aggressive treatment may lead to precipitous drops in blood pressure, which may in turn cause low perfusion in areas that are already marginal.

“Our results may offer potential therapeutic possibilities in preventing and reducing the attendant cognitive decline and dementia,” the investigators propose, but they caution that potential adverse effects of lowering blood pressure too much should also be considered.

Dementia is becoming one of the major causes of disability and mortality, Drs. Jan A. Staessen and Willem H. Birkenhager point out in an editorial.

The authors discuss the pros and cons of different blood pressure-lowering drugs in terms of preventing dementia, and note that there’s some evidence that calcium channel blockers have a particular benefit.

“In view of the human suffering, clinical trials must be mounted to specifically address the question of whether blood pressure-lowering with or without calcium channel blockade can prevent Alzheimer disease,” they add.

Dr. Staessen is based at the University of Leuven in Belgium, and Dr. Birkenhager is at Erasmus University.

SOURCE: Hypertension, November 2004.