Doctors have long known that high blood pressure -- which makes the heart work too hard -- can lead to heart disease, kidney disease and blindness. Now new research has found that high blood pressure in middle age may also impact memory and thinking in old age.
For the study, researchers examined the blood pressure of more than 4,000 older dementia-free participants during middle age (average age of 50) and then again at the average age of 76. Participants underwent MRIs that looked at structure and damage to the small vessels in the brain. They also took tests that measured their memory and thinking ability.
The findings showed that blood pressure in old age and brain measures were directly linked to the history of blood pressure in middle age. Higher systolic (the top number on the measure of blood pressure) and diastolic (the bottom number on the measure of blood pressure) blood pressures were to blame for an increased risk of brain lesions and tiny brain bleeds. This was most noticeable in people without a history of high blood pressure in middle age. For example, people with no history of high blood pressure in middle age who had high diastolic blood pressure in old age were 50 percent more likely to have severe brain lesions than people with low diastolic blood pressure in old age.
However, in people with a history of high blood pressure in middle age, lower diastolic blood pressure in older age was associated with smaller total brain and gray matter volumes. This finding was reflected in memory and thinking performance tests as well. In people with high blood pressure in middle age, lower diastolic blood pressure was linked with 10 percent lower memory scores.
Study author Dr. Lenore J. Launer, of the National Institute on Aging in Bethesda, Md., said the findings shed new light on the relationship between a history of high blood pressure, blood pressure in old age, and memory and thinking ability.
"Older people without a history of high blood pressure but who currently have high blood pressure are at an increased risk for brain lesions, suggesting that lowering of blood pressure in these participants might be beneficial. On the other hand, older people with a history of high blood pressure but who currently have lower blood pressure might have more extensive organ damage and are at risk of brain shrinkage and memory and thinking problems," said Launer in a press release.
About one in three U.S. adults -- or 67 million people -- have high blood pressure. High blood pressure is often referred to as "the silent killer" because of its lack of symptoms.
Another study released earlier this year also found that high blood pressure in middle age -- as well as type 2 diabetes -- can contribute to dementia as a person grows older.