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Dementia Rates Are on the Decline in U.S.

Posted on: Thursday, 21 February 2008, 00:00 CST

SEATTLE -- Older adults today appear to have significantly less risk of memory loss and dementia than a decade ago, likely because they're better-educated, wealthier and receive better health care for cardiovascular disease, according to a nationwide study co-authored by a Group Health researcher.

The downward trend, reported online Wednesday in the journal Alzheimer's & Dementia, found 8.7 percent of participants age 70 and older had cognitive impairment _ from significant memory loss to full-blown Alzheimer's disease _ compared to 12.2 percent in 1993.

The new study, which is unusually large and comprehensive, offers the best data ever on whether the rate of dementia is declining over time as Americans have become healthier, said co-author Dr. Eric Larson, executive director of the Group Health Center for Health Studies.

It also offers some hope in an era when dementia is considered a looming public-health crisis as more baby boomers enter old age.

"This says to me that we shouldn't just be focused on finding a cure for persons who already have dementia," Larson said. "Rather this suggests that prevention and delay of onset actually can occur."

More than 5 million Americans are estimated to be living with Alzheimer's, the most common form of dementia, a progressive and ultimately fatal disease that damages and kills areas of the brain. More than 65,000 Americans died of Alzheimer's in 2004, according to the Centers for Disease Control and Prevention.

The new study data comes from the Health and Retirement Study, a national survey of 11,000 older adults funded by the U.S. National Institute on Aging and based at the University of Michigan Institute for Social Research.

Their cognitive function was tested on a 35-point scale and included counting backward, object naming, recalling the day's date, and naming the president and vice president.

The research team was comprised of social and medical scientists from the University of Michigan, the University of Pennsylvania and Harvard University, in addition to Group Health.

The study found that more years of education may have influenced the prevalence and outcomes of dementia. The proportion of adults 65 and older with a high-school diploma increased from 53 percent in 1990 to 72 percent in 2003. The proportion of those with a college degree increased from 11 percent to 17 percent during the same time period.

The added years of education, according to the study, likely led to higher brain development and function, better health behaviors and the "general advantages of having more wealth and social opportunities."

However, older adults with more education were at higher risk of dying within two years of dementia's onset, the study found. That might indicate they built up a "cognitive reserve" over their life, so their brain was protected longer against the assault of dementia. When a crisis hits, such as a stroke, their last mental reserve is depleted and death comes sooner.

"You've got this natural tendency for brains to deteriorate as they age," Larson said. "But something about the way we live has caused the cognitive decline to delay."

That means "when you get truly impaired, you're closer to when you're naturally going to die, which many people would prefer," Larson said.

At the same time, the use of cholesterol-lowering drugs, blood-pressure medications and other tools to prevent heart and blood-vessel disease also increased in the 1990s, which might have decreased the risk of stroke leading to cognitive problems and dementia.

While the use of a new generation of drugs to treat Alzheimer's also has increased dramatically, they primarily are used after a diagnosis of the disease and the impact is modest, the authors said. So it's very unlikely this explains the decreased prevalence of cognitive impairment, the study found.

Overall, the findings "engender optimism," the authors conclude. However, the gains may be offset by the current epidemic of type 2 diabetes, obesity and high blood pressure. And, no matter what, the number of Americans who will get dementia likely will increase as the number of older Americans climbs.

At age 87, Adrian Lawler of West Seattle could be a poster-elder for how to keep the brain and body fit. Although he's participating in a healthy-aging study at Group Health, he says he's not trying to ward off dementia intentionally. But his sharp thinking could be a side benefit to his active lifestyle, he said.

The retired Boeing engineer and teacher snow skis and hikes with his dog, volunteers at the blood bank and runs a small business on the side. He "keeps a good diet" and takes preventive medication for heart disease. And other than misplacing hearing aids occasionally, he has no serious memory lapses.

In other words, he suggested, if a person has a pet to walk, a hobby that requires intellectual inquiry and a volunteer activity that helps others "you have a better feeling and you live longer."

Source: The Seattle Times

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