Raji Cyrus/UCLA

A profile MRI of the brain with color shaded areas corresponding to areas of increased gray matter volume in active people. The blue crosshairs point to increased volume in the hippocampus with more calories burned per week. The hippocampus is the key memory and learning center of the brain.

Seniors who fit in the most daily physical activity – from raking leaves to dancing – can have more gray matter in important brain regions, researchers reported on Monday.

The scientists have images that show people who were the most active had 5 percent more gray matter than people who were the least active. Having more little gray brain cells translates into a lower risk of Alzheimer’s disease, other studies have shown.

“People really want to know what they can do to reduce their risk of Alzheimer’s disease,” said Dr. Cyrus Raji of the University of California in Los Angeles, who presented his team’s findings to a meeting of the Radiological Society of North America.

“This shows it is easier than you think.”

Raji’s team looked at the records of 876 adults, who were recruited into a larger study on heart health starting in 1989. They all got magnetic resonance imaging (MRI) brain scans in 1998 and 1999, when they were on average 78 years old, and filled out detailed questionnaires on exercise and other types of activity.

Most of them were a little overweight – with a body mass index or BMI of 27. People with BMIs above 25 are considered overweight and at 30 they are considered clinically obese.

The researchers found a huge difference in the amount of activity people reported. They were asked about everything from cycling to yard work, dancing and bicycle riding.

“The most active burned 3,434 calories per week (an extra 500 calories per day on average) compared to those in the bottom percentile who only burned 348 calories per week [through activities],” Raji said. “The most active had 5 percent more gray matter volume than the least active. That's a big number when you think about the tremendous biological forces that have to be at work for brain volume to change at all.”

And the MRIs showed the differences were in areas of the brain like the hippocampus, which is heavily damaged in Alzheimer’s disease.

“By strengthening this area, an active lifestyle can reduce risk for Alzheimer's,” Raji said. "Virtually all of the physical activities examined in this study are some variation of aerobic physical activity, which we know from other work can improve cerebral blood flow and strengthen neuronal connections.”

Money is limited for new medical research, so the UCLA team went through the records from another study -- that explains why some of the data is old. "This is the largest study of its kind that has ever been done," Raji said.

But even older data can be a gold mine for researchers. To log exercise, the volunteers wrote down all the activities they could remember over a two-week period. Some went back and filled out questionnaires five years later, so Raji's team could make some comparisons.

"We found that individuals who increased calories burned over five years also had more gray matter volume," Raji said.

Raji isn't sure how some people only managed to burn off 348 extra calories a week, but said they may have been ill or even bedridden.

When they looked in more detail at the surveys, the researchers noted that it was the people who managed to work exercise into their daily lives who racked up the most weekly calories. So unless people enjoy standard “exercise” such as running, they should find something they like and are likely to stick to, said Raji.

“No pharmaceutical drug on the market has been shown to have these effects on the brain -- not a single drug,” said Raji. And exercise is available to anyone. “And it doesn’t cost anything,” he said.

In the first 10 years of the study, 97 people developed Alzheimer’s, and just about a quarter of them were in the top 25 percent of exercisers. Raji said the disease was detected very early in this study because the volunteers were being studied so intensely. “Most had not yet been diagnosed by their primary care physicians,” he said.

Now the team is going to go through the surveys to see if the people who had the most gray matter were the least likely to develop Alzheimer’s – or if the brain disease progressed more slowly in those with the most gray matter. And they want to follow up with as many of the volunteers as possible to see how they have fared.

“I really do believe that we have strong evidence that physical activity can be a way to reduce the risk of Alzheimer’s disease,” Raji said.

How many calories can you burn doing various activities? The Centers for Disease Control and Prevention has a calculator here. An hour of dancing can burn 330 calories an hour while walking burns about 280 calories an hour.

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• Why working out makes you live longer
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When it comes to the elderly, almost no one wants to talk about sex. This is especially true when nursing home and residential care are involved.

According to new report by a group in Australia in the Journal of Medical Ethics, the idea that adults should be able to engage in sexual relationships whenever, and with whomever, they choose becomes very complicated for residents in most nursing homes. For residents with dementia, romantic intimacy is especially discouraged.

Many older people, including those with early stage dementia, enjoy sex while living at home with their spouses. But this ends once they move into a nursing home, even for long-term couples, note the researchers from the Australian Centre for Evidence-Based Aged Care. Married or not, sex ends at the nursing home door.

Nursing homes are simply not set up to permit romance. Privacy is at a premium and few room doors lock. Most rooms are double-occupancy with single beds. And nursing home staff don’t typically encourage romance and sex. It's one less thing for nursing home owners and administrators to worry about.

We're so prudish about the elderly and intimate relationships that we don’t even broach the topic when a loved one is heading to a home. We consider freedom and autonomy when debating who will have the right to pull the feeding tube or turn off the dialysis machine if Mom or Dad can't communicate, but we do nothing to ensure their right to enjoy themselves in an area of life that matters a great deal to them.

Sex may not be for every nursing home resident, but it is surely for some. That's autonomy worth talking about.

A nursing home ought be at least as tolerant as a prison. Some prisons permit conjugal visits. Shouldn’t we expect the same of nursing homes? If you care about your parents' and grandparents' dignity, sex ought to be a topic of conversation regarding the nursing home if that's where they're headed or where they now live.

Bioethicist Art Caplan is the head of the Division of Medical Ethics, NYU Langone Medical Center.

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Even people in their 80s may be able to lower the risk of Alzheimer’s simply by increasing how much they move around each day, a new study suggests.

In a four-year study of 716 elderly Americans, researchers found that the least active seniors were more than twice as likely to develop Alzheimer’s disease compared to the most active.

Seniors’ activity levels were measured with an actigraph, a watch-sized device worn on the wrist that detects movements all through the day and night.

Intriguingly, much of the movement measured by the actigraphs came from regular daily activities, such as cooking, washing dishes, or cleaning, rather than formal exercise, said the study’s lead author, Dr. Aron Buchman, a professor of neurological sciences at the Rush Alzheimer’s Disease Center at the Rush University Medical Center.

The take home message, Buchman said, is that even people who have disabilities that prevent them from exercising can benefit just by making sure they move around a lot. “So even if you’re housebound, you may benefit from increasing whatever you do in the house,” he added.

An Alzheimer’s expert who is unaffiliated with the new study called the results “a fabulous finding.”

“I think this study is very simple and it has a very simple and very clear message: move more,” said Dr. Steven Arnold, a professor of psychiatry and neurology at the University of Pennsylvania and director of the Penn Memory Center. “The bottom line is that people who tend to be more active than others have a lower risk.”

For the new study, Buchman and his colleagues asked 716 volunteers without dementia to wear an actigraph on their non-dominant wrist continuously for 10 days. The volunteers had an average age of 82.

The volunteers were given annual cognitive tests to measure memory and thinking abilities. They were also asked to fill out surveys that asked about physical and social activities.

Because the new research is part of a larger, ongoing long-term study, Buchman and his colleagues also had information on volunteers’ health before the activity measurements.  “There was no association between activity level and prior rate of cognitive decline,” Buchman said. “So it’s not like people with low activity were already on a trajectory toward dementia or more rapid cognitive decline.”

Four years after the volunteers had done the actigraph experiment, 71 had developed dementia. When the researchers compared physical activity of the volunteers, they determined that those in the bottom 10 percent of intensity of physical activity were 2.8 times as likely to develop Alzheimer’s disease compared to those in the top 10 percent. And those results held up even when the researchers accounted for factors such as age, gender, chronic illness and depression.

Arnold isn’t surprised to see that risk went down with the intensity of physical activity. Animal studies have shown that the brain actually makes new cells when animals exercise. But that’s only when the animals choose to exercise, Arnold said.

“It’s interesting that if the mouse is forced to run on a wheel, it doesn’t have as good an effect as when the exercise is voluntary,” Arnold said. “Usually if you put them on a wheel they’ll just run for fun.”