"The groundwork of all happiness is health." - Leigh Hunt

PET scans peer at the guts of dementia.

What's bad on your heart is usually bad on your mind. High cholesterol, hypertension, diabetes, and unhealthy “hardening” of the arteries increase your risk of mental decline or dementia later in life. A study was published online today. Neurology It opens a window into how heart disease affects the brain and should even result in some necessary insights into Alzheimer's disease.

Researchers from the University of Pittsburgh and the University of Virginia found that elderly individuals with probably the most hardened arteries showed the form of brain tissue damage often seen in individuals with dementia. Although a heart-unhealthy lifestyle has been linked to an increased risk of Alzheimer's disease, probably the most common type of dementia in older adults, the findings of this study suggest there could also be a silver lining: “This is more evidence that cardiovascular health leads to a healthy brain,” says University of Pittsburgh researcher Timothy Hughes, Ph.D., lead writer of the study.

In the past, looking closely at each the brain and the health of the arteries could only be done in individuals who had died, since an autopsy was crucial to acquire brain tissue samples. gave Neurology The study provides a glimpse into living brains—and a chance to check the changes that result in full-blown dementia.

Peeking into minds

Hughes and his fellow researchers studied 91 elderly men and ladies, with a mean age of 87, who were still living independently of their communities. Each underwent a special form of PET brain scan to search for beta-amyloid, the sticky protein that accumulates within the brains of most individuals with Alzheimer's disease. Amyloid deposits, called plaques, cause the devastating changes within the brain and memory which might be hallmarks of Alzheimer's disease.

Although not one of the participants showed signs of dementia, about half of them had significant amounts of amyloid deposits of their brains. “We didn't expect to see so many plaques in so many study participants without dementia,” says Hughes.

Study participants also underwent a series of tests for cardiovascular health. A measured arterial stiffness, an indicator of the health of the body's arterial network. Most people know the hardening of the arteries as “hardening of the arteries,” which is brought on largely by hypertension and other damage to the artery partitions. In general, arteries harden with age. People with the stiffest arteries usually tend to show two varieties of brain changes:

  • PET scans showed more amyloid plaques. Such plaques have been linked to Alzheimer's disease.
  • More damage to the brain's “white matter” seen on MRI scans. White matter consists of nerve fibers that send messages between different centers of the brain. White matter loss is an indication of trouble within the small arteries liable for nourishing brain tissue. “The MRI scans were picking up disease in the small arteries in the brain that is likely being caused by vascular disease in the body,” Hughes explains.

Two “hits” on the brain.

In addition to confirming the ravages of heart problems on the brain, the study provides some clues which will help solve a long-standing mystery concerning the link between amyloid protein and Alzheimer's disease. Many individuals with significant amounts of amyloid of their brains don't show symptoms of dementia. Yet aging can sometimes push them toward dementia. What happens within the brain to do that?

One possible answer is often known as the “two-hit” theory of amyloid and vascular disease. Some research shows that “amyloid accumulates in the brain for years and decades until the brain can't compensate and cognitive impairment begins,” Hughes says. A mix of amyloid deposition and damage to the small arteries that nourish brain tissue could, hypothetically, tip the scales. “Amyloid deposition and vascular disease can be a double hit that can really cause a person to turn into dementia.”

It's still speculation, but with the ability to track each amyloid protein deposits and physical damage to the brain over time in living people may give us a solution—and a robust technique to reverse dementia. “Vascular health leads to brain health,” Hughes says. “That's the big central idea here. If the same is true in young adults, it may give us a way to prevent amyloid accumulation later in life.”

In other words, a healthy weight loss program, each day exercise, not smoking, and healthy lifestyle selections from early maturity can keep the brain and heart in good condition for a long time.