November 2, 2012
Elevated Blood Pressure In Your 40s Could Affect Brain Function
Lee Rannals for redOrbit.com - Your Universe Online
This suggests that vascular brain injury "develops insidiously over the lifetime with discernible effects," the researchers wrote in the medical journal The Lancet Neurology.
The study is the first to demonstrate that there is structural damage to the brains of adults in young middle age as a result of high blood pressure.
Structural damage to the brain's white matter caused by high blood pressure has been associated with cognitive decline in older individuals.
Study senior author Charles DeCarli, professor of neurology and director of the UC Davis Alzheimer's Disease Center, said the research emphasizes the need for lifelong attention to vascular risk factors for brain aging.
"The message here is really clear: People can influence their late-life brain health by knowing and treating their blood pressure at a young age, when you wouldn't necessarily be thinking about it," DeCarli said. "The people in our study were cognitively normal, so a lack of symptoms doesn't mean anything."
Normal blood pressure has a systolic blood pressure below 120, and a diastolic pressure below 80. Prehypertension blood pressure range is a top number between 120 and 139, and a bottom number between 80 and 89.
Elevated blood pressure affects about 50 million Americans and is associated with a 62 percent risk of cerebrovascular disease, and a 49 percent risk of cardiovascular disease.
Earlier studies identified associations between elevated blood pressure and a heightened risk of brain injury and atrophy leading to reduced cognitive performance and a greater likelihood of dementia.
The study says there is evidence that lowering blood pressure among people in middle age and in the young elderly can help prevent late-life cognitive decline and dementia.
The research sought to decipher the age of onset, extent and nature of the effects of elevated systolic blood pressure on cognitive decline among participants.
The study included 579 Framingham participants who were an average of 39 years old when recruited for participants in the study. Their blood pressure was measured as the average of two physician-recorded blood pressures.
The study subjects were then organized into groups with normal blood pressure, those who were prehypertensive, and those with high blood pressure. Whether they were receiving treatment for blood pressure and whether they smoke was also considered.
The team used magnetic resonance imaging (MRI) to determine the participants' brain health using a variety of measurements of white matter injury and gray matter volume. The MRI exams included diffusion tensor imaging, which is a kind of image that reveals microscopic details of tissue architecture within the white matter of the brain.
In the hypertensive participant, fractional anisotropy in the frontal lobes was dredged by an average of 6.5 percent. These patients also had 9 percent less gray matter in their brains' frontal and temporal lobes.
The authors concluded that hypertensive individuals' brains were significantly less healthy than those of subjects with normal blood pressure. A typical 33-year-old hypertensive's brain health was similar to that of the typical 40-year-old normotensive subject.
The authors noted that high blood pressure causes arteries to stiffen, making the blood flowing to the brain pulse more strongly.
"This work suggests that recently described white matter microstructural damage associated with high blood pressure in the elderly may be detectable earlier in the life span, further reinforcing the view that vascular brain injury may develop insidiously over several decades," said Pauline Maillard, the study's lead author and a postdoctoral fellow in the UC Davis Department of Neurology. "These results emphasize the need for early and optimum control of blood pressure, which is neither routinely achieved nor subject to testing in randomized controlled clinical trials."