Healthnotes Newswire (June 21, 2001)—People with high blood pressure or high cholesterol levels in midlife are twice as likely to develop Alzheimer’s disease in later life than are people with normal blood pressure and cholesterol levels, according to a study published this week in the British medical journal BMJ.¹

The 1,449 participants in the study were residents of Eastern Finland. They were studied for an average of 21 years, and were aged 65 to 79 years of age at the time of re-examination for Alzheimer’s disease in 1998. Those with raised systolic blood pressure (greater than or equal to 160 millimeters of mercury on a blood pressure gauge) or high blood levels of cholesterol (greater than or equal to 6.5 millimoles per liter [about 250 milligrams per deciliter]) in midlife had a significantly higher risk of Alzheimer’s disease in later life. Participants with both risk factors in midlife had 3.5 times the risk of Alzheimer’s disease than those with neither risk factor. Surprisingly, diastolic blood pressure had no apparent effect on Alzheimer’s risk in this study.

Most people know that blood pressure is expressed as two numbers: the upper number (called systolic blood pressure) refers to the amount of pressure generated in the cardiovascular system when the heart contracts and fills the body’s arteries with blood; the lower number (called the diastolic blood pressure) is the system’s resting blood pressure between heart contractions. A normal blood pressure for a healthy adult is about 120/80 millimeters of mercury (mmHg) on a blood pressure gauge.

Previous studies have linked raised diastolic blood pressure^{2 3} and high cholesterol⁴ with Alzheimer’s disease. Together with the new study, they highlight the importance of identifying early risk factors for Alzheimer’s disease, because the degenerative process of Alzheimer’s disease may begin in midlife⁵ and prevention is the best defense.

High blood pressure and high cholesterol are thought to increase the risk of Alzheimer’s disease by inducing atherosclerosis (hardening of the arteries) and thus impairing blood flow to the brain. People with atherosclerosis have previously been found to have an increased risk of Alzheimer’s disease.⁶ But these cardiovascular risk factors may also induce degeneration in the brain directly.⁷ Indeed, the new study’s findings linking high blood pressure and high cholesterol with Alzheimer’s disease remained even after the authors excluded participants who had had "vascular events," such as heart attack and stroke, caused by atherosclerosis. This suggests that high blood pressure and high cholesterol may directly contribute to Alzheimer’s disease.

As the proportion of elderly people in the population continues to rise, Alzheimer’s disease will become an even greater major public health problem. Any preventive strategy that can delay the onset of the disease, even slightly, is likely to have a major impact on the health of the elderly in this country. High blood pressure and high cholesterol can be effectively prevented and treated with lifestyle and dietary modifications (such as exercise and a diet high in fiber and low in saturated fats). These same simple interventions may also prevent the development of Alzheimer’s disease.^{8 9}