Mid-life stress linked to dementia risk

A large, long-term study reveals that dealing with stress during middle age may trigger lasting physiological brain changes, increasing the risk of developing dementia later in life.
This finding comes from the Prospective Population Study of Women in Gothenburg, Sweden, which started in 1968 and followed over 800 Swedish women for around 40 years. Results of the study were published online in the journal BMJ Open.
Researchers from the study looked at previous studies showing how stress can cause both structural and functional brain damage, as well as promote inflammation.
They say stress hormones can remain at high levels, long after a traumatic event has passed.
Previous studies looked at the effect of severe psychological stressors in adulthood, such as combat, natural disasters and the Holocaust, and they revealed that mental and physical health were affected decades later.
However, the researchers say that although mild psychosocial stressors are a regular part of life, the "long-term consequences of these more common stressors" have remained unclear.

Data over 40 years shows increased risks

Women who experienced certain stressors during middle age had a 21% increased risk for Alzheimer's and a 15% increased risk for dementia, according to the study.

The women who were part of this recent study were all born in 1914, 1918, 1922 and 1930. They underwent neuropsychiatric tests and exams in 1968, and then again in 1974, 1980, 1992, 2000 and 2005.
In 1968, at the start of the study, the women were asked about the psychological impact of 18 common stressors, including divorce, widowhood, illness or death of a child, mental illness or alcoholism in a family member, unemployment and poor social support.
At each follow-up visit, researchers documented how many symptoms of distress - irritability, fear or sleep disturbances - each woman had experienced in the preceding 5 years.
One in four of the women had experienced a minimum of one stressful event at the start of the study. The most common stressor was mental illness in a close family member (sibling 32%, mother 27%, father 19%).
Between the monitoring period of 1968 and 2006, about one in five - 153 in total - of the women developed dementia, and 104 of them developed Alzheimer's disease.
Dementia was diagnosed at an average age of 79, and it took 29 years for it to develop, the researchers say.
The number of stressors the women reported in 1968 was associated with a 21% increased risk of developing Alzheimer's disease and a 15% increased risk of developing any kind of dementia, according to the study.
The researchers note that these findings remained the same, even after factoring in elements that could influence the results, such as a family history of mental health problems.

'More research needed'

Though the study concludes the research does indeed show that common psychosocial stressors have long-term consequences, the authors say that more studies are needed to confirm the results.
They also recommend further study of interventions, such as stress management and behavioral therapy, to see whether these could be useful for people who have experienced the contributing stressors.
Dr. Lena Johansson, co-author of the study, told Medical News Today that she and her colleagues are planning to continue the research project and extend it to a sample of men in a study taking place in Gothenburg, in order to further analyze the relationship between stressors and dementia.

Fluctose may affect hunger cues

Fluctose may affect hunger cues

Jan. 2, 2013 -- All sugars are not created equal, at least when it comes to the brain, a new study shows.

For the study, which is published in the Journal of the American Medical Association, researchers asked 20 healthy men and women to sip a cherry-flavored drink sweetened with either pure glucose or pure fructose.  

Both glucose and fructose are simple sugars. People rarely take in either one by itself. Instead, they’re usually added to foods and drinks as mixtures. Table sugar is about half glucose, half fructose, for example, while high-fructose corn syrup is about 55% fructose and 45% glucose.

Fructose is sweeter than glucose. It’s also less expensive. So over the years, the balance of calories from added sugars in the American diet has shifted to favor fructose.

“People consume a lot more fructose now than they used to, because it’s cheaper to put high-fructose corn syrup in the foods we eat,” says researcher Robert S. Sherwin, MD, an endocrinologist at the Yale University School of Medicine, in New Haven, Conn. 

Whether that shift may be contributing to our nation's growing obesity problem has been an open question.

Animal studies have shown that glucose and fructose can have different effects on appetite and metabolism. Sherwin and his team set out to see if that might also be true for humans.

Sugars in the Brain

Each person in the study completed the experiment twice with a gap of a few weeks to a few months between lab visits. They weren’t told which sugar they were given to drink.

Each time, they were given a scan that allowed researchers to watch what was happening to their brains in real time.

Study scientists were particularly interested in changes to a region called the hypothalamus, which helps to control appetite. They also took blood samples to check levels of hormones that control feelings of hunger and fullness, and asked the study participants how satisfied they felt after drinking the different sugar solutions.

As quickly as 15 minutes after people in the study finished the drinks, researchers began to see changes in brain blood flow and activity.

After the glucose drink, the body seemed to recognize and respond to the extra calories with an increase in glucose and insulin levels. That response, which blunts hunger, was significantly greater than fructose's. Brain activity also slowed in the hypothalamus, the region that stimulates appetite.

After the fructose drink, on the other hand, the hypothalamus continued to stay active. There was little increase in insulin, and study volunteers said they felt hungrier, even though they weren’t told which sugar they’d had.

Other hormones that are known to regulate hunger, such as ghrelin and leptin, were unchanged after ingestion of either type of sugar.

Sugars in the Brain continued...

“When we eat, the body recognizes that food is coming in, and ultimately the brain is trying its best to regulate how many calories we need and how much fat we have in our bodies, and trying to maintain a balance so that we’re not overeating or under-eating,” Sherwin says. 

Fructose seems to upset that balancing act, though researchers aren’t sure why.

One theory is that when humans evolved, the problem wasn’t overeating, but not getting enough calories. In that case, it wouldn’t have been a good idea for fructose, which is the primary sugar in fruit and fruit juices, to make us feel full since fruits may have been a primary food source.

That may have worked fine for cavemen, but it may not be so great for our sugar-saturated modern diets.

Advice to Dieters

So what does the study mean for health-conscious eaters?

That’s harder to say, says Jonathan Purnell, MD, an endocrinologist at Oregon Health & Science University in Portland.  Purnell wrote an editorial on the study but was not involved in the research.

“This study didn’t prove that fructose causes weight gain,” Purnell says. “It doesn’t reflect real-world conditions.”

Industry representatives agree.

“When consumed together, as they almost always are, fructose and glucose balance each other out and would likely have no effect on normal hypothalamic blood flow,” says James Rippe, MD, professor of biomedical sciences at the University of Central Florida and a paid consultant for the Corn Refiners Association, the group that represents manufacturers of high-fructose corn syrup.

“Any suggestion that this artificial experiment has implications for human nutrition or obesity is unwarranted speculation,” says Rippe, in a statement prepared in response to the study.

Ideally, Purnell says, the next phase of studies would test the kinds of sugar mixtures found in foods, like table sugars and high-fructose corn syrup, against a comparison condition like water or an artificial sweetener.

“This study shouldn’t, all by itself, lead people to cut back on this food or that food,” Purnell says.

It would be a mistake, he says, to give up fruit, which has naturally occurring fructose.

“We don’t recommend limiting fruit intake. Although there’s fructose there, it’s also present with water and fiber that alter the characteristics of straight fructose alone. We think that doesn’t make fruit as much of a bad actor,” Purnell says.

What’s probably more practical, says Rachel Begun, RD, a spokeswoman for the American Academy of Nutrition and Dietetics, is to try to limit added sugars.

Americans take in nearly 150 pounds of added sugars per year, according to the U.S. Department of Agriculture, an amount that breaks down to nearly 28 teaspoons or 440 calories every day.

“It's safe to say that Americans are consuming too much sugar in all forms and we need to significantly reduce our intake," says Begun, who wasn’t involved in the research.