Dementia rate fell 44% since late 1970s in U.S. town - Action News
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Health

Dementia rate fell 44% since late 1970s in U.S. town

Dementia is on the decline, according to a new analysis of health records from thousands of people in one Massachusetts town.

Improvements only seen among people who had graduated from high school

Dementia is on the decline, according toa new analysis of health records from thousands of people in oneMassachusetts town.

The new report, using data from the long-running FraminghamHeart Study, shows that dementia rates have decreased by 44per cent since the late 1970s and early 1980s, with nearly all ofthat drop among high school graduates.

It was a collective reduction in all causes of senility thatproduced the significant fall, researchers said. Dementia causedby vascular diseases, such as stroke, accounted for the much ofthe drop. Alzheimer's disease showed a reduction, but it wasn'tdramatic, and could be a statistical fluke, they said.

"There was a trend there" for Alzheimer's, said DeanHartley, director of science initiatives with the Alzheimer'sAssociation. It shows "there may be modifiable lifestyles thatmay lower your risk for Alzheimer's."

So many people are entering the age when dementia becomes athreat and life expectancy is increasing so rapidly, the declinein rates of dementia will not translate to an overall drop inthe number of dementia cases, cautioned senior author Dr. SudhaSeshadri, a professor of neurology at the Boston UniversitySchool of Medicine.

"We don't know completely what's bringing down the rates,"she told Reuters Health. "The good news is, we are doing
something right. The bad news is we need to understand this muchbetter if we want to effectively continue the trend."

The Framingham study is based in a predominately-whiteMassachusetts town west of Boston where thousands of residentshave been closely followed by doctors since 1948. The newanalysis, reported in the New England Journal of Medicine,looked at dementia rates in four 5-year blocks and used datafrom 5,205 individuals.

Dementia rates were 3.6 per cent among people aged 60 yearsand older beginning in 1977, falling to 2.8 percent for theblock of people who were over 60 beginning in 1986, then 2.2per cent for the block starting in 1992 and 2.0 per cent for themost recent block, from 2004 to 2008.

Those declines translate to reductions of 22 per cent, 38per cent and 44 per cent in the second, third and fourth period,respectively, compared to the rate in the early years.

More education and brain power?

The researchers said some of the drop may be due to declinesin rates of stroke, heart failure and atrial fibrillation, aswell as better treatments for those conditions, "but none ofthese trends completely explain the decrease in the incidence ofdementia."

Residents without a high school diploma showed no decline indementia, perhaps because improvements in heart health were onlyseen among people who had graduated from high school, the studyteam notes.

Dr. Paul Schulz, a dementia neurologist at the University ofTexas Health Science Center in Houston, who was not connected tothe research, pointed out that "there's a lot of healthcareaccess issues related to education (and graduates) may havebetter insurance to see their doctor more often," which mighthave affected the results.

In addition, he said, "People who have more education may beblessed with more brain power. They may have more ability tolose function before they develop symptoms. In this studythey're speculating that getting more education might bevaluable, but it might be a chicken and egg question here."

Dementia also tended to show up later in life as time wenton, the study found. The average age of diagnosis was 80 duringthe late 1970s and 85 in the most recent group.

"Rising educational levels might have contributed to the5-year delay we observed in the mean age at onset of clinicaldementia," the researchers said.

"One of the limitations of the Framingham Heart Study isthat the participants are overwhelmingly of European ancestry;therefore, our findings would need to be replicated in groupsthat include a larger number of participants of other races andethnic backgrounds," they cautioned.

Hartley said it's important to fund more research to seewhat lifestyle changes might lower the risk further. "A numberof things people to do to stay healthy" such as exercise, abetter diet and social stimulation "could protect their brain,"he said