WEDNESDAY April 16 (HealthDay News) -- Regular physical exercise may help protect against mild cognitive impairment, according to a Mayo Clinic study.

People with mild cognitive impairment can handle everyday activities but often have trouble remembering details of conversations, events and upcoming appointments. Most, but not all, people with mild cognitive impairment experience a progressive decline in their cognitive abilities, and the underlying cause is usually Alzheimer's disease, according to background information in the study.

The physical benefits of exercise are well-known, but this is one of the first studies to examine whether exercise can help protect the brain.

The Mayo researchers randomly selected 868 people, aged 70 to 89, taking part in the ongoing Mayo Clinic Study of Aging. Of these people, 128 had mild cognitive impairment, and 740 were cognitively normal. The researchers conducted surveys to gather data on the participants' levels of exercise between the ages of 50 and 65 and during the year prior to the survey.

Moderate physical exercise between the ages of 50 and 65 was associated with a reduced risk of cognitive impairment, but the same was not true of exercise during the year prior to the survey.

The study was expected to be presented Wednesday at the American Academy of Neurology annual meeting, in Chicago. Lead investigator and neuropsychiatrist Dr. Yonas Endale Geda said the findings need to be replicated in a prospective cohort study, and also noted that this study did not address how physical exercise may protect against mild cognitive impairment.

"Regarding the mechanism of action of physical exercise and mild cognitive impairment, we speculate that either exercise induces chemicals that protect brain cells, or exercise is simply a marker for an overall healthy lifestyle, or there is some positive interaction among exercise, healthy lifestyle and intellectually stimulating activity," Geda said in a prepared statement.

More information

The Alzheimer's Association has more about mild cognitive impairment  .

THURSDAY, April 10 (HealthDay News) -- After declining for several years, reports of foodborne illnesses have remained constant in the United States since 2004, federal health officials said Thursday.

And that leveling off of the rate of food poisonings casts into doubt the U.S. Centers for Disease Control and Prevention's goal of reducing the overall number of foodborne infections by 2010.

"Food safety is a continuing problem that starts at the farm and continues through the food chain all the way to the kitchen," Dr. Robert Tauxe, deputy director of CDC's Division of Foodborne, Bacterial and Mycotic Diseases, said during a teleconference.

Given that rates of foodborne infection haven't changed significantly in the past three years, more needs to be done to improve food safety, Tauxe said "We have to be vigilant about hygiene practices and prevention all along the way to reduce the risk of foodborne infection," he said.

Tauxe said there have been significant declines in foodborne pathogens since 1996, but all the declines happened before 2004. "If we compare 2007 with the previous three years, we are not seeing significant changes in the incidence of these pathogens," he said.

For instance, the number of salmonella infections has changed very little since a federal monitoring system was established in 1996, Tauxe said. "We need more effort at all stages of food production, from farm to table, to effectively prevent the contamination of food from salmonella," he said.

In 2007, there were large outbreaks of salmonella poisonings linked to peanut butter and frozen pot pies, Tauxe noted.

E. coli infections reached a low point in 2003 and 2004, but increased again in 2005 and 2006, Tauxe said. The rate for 2007 was 14.92 diagnosed infections for every 100,000 Americans. Although that number was lower than the 2006 number of infections, it wasn't significantly different from the number of E. coli infections seen in 2004 in 2005, he said.

Tauxe said, "2006, of course, was the year of large outbreaks related to spinach and shredded lettuce, and 2007 was marked by a number of ground beef recalls."

Comparing statistics from 2007 to 2004 to 2006, the incidence of infections from campylobacter, listeria, shigella, vibrio, and yersinia did not drop significantly, he said.

The number of cryptosporidium infections increased, but that was probably due to better reporting rather than an actual increase in the number of infections, Tauxe said.

The findings came from the CDC's Foodborne Diseases Active Surveillance Network -- FoodNet -- which monitors foodborne disease in 10 states. The report findings were published in the April 11 issue of the CDC's Morbidity and Mortality Weekly Report.

In 2007, they were total of 17,883 confirmed cases of foodborne infections, according to the report. The greatest number of cases was seen for salmonella, with an incidence rate of 14.92 per 100,000 people. Campylobacter infections were the next most common infection, with an incidence rate of 12.79, per 100,000 people. Next were shigella infections, with an incidence rate of 6.26 per 100,000 people.

The rates of infections were particularly high among children under 5 years of age, according to the report. Risk factors for these bacterial illnesses in young children include riding in a shopping cart next to raw meat or poultry, going to a day-care center, visiting or living on a farm, and having a pet turtle or other reptile, according to the report.

More information

For more on foodborne illness, visit the US Centers for Disease Control and Prevention.

WEDNESDAY, April 9 (HealthDay News) -- A little caffeine every day could offer some protection from Alzheimer's disease for people with high cholesterol.

Rabbits given the daily caffeine equivalent of one cup of coffee and fed a cholesterol-rich diet for 12 weeks suffered relatively little damage in their blood-brain barrier (BBB), which protects the central nervous system from the rest of the body's circulation, new research found.

The findings were published in the open-access publication Journal of Neuroinflammation.

Previous studies have shown that high levels of cholesterol break down the BBB, exposing the central nervous system to damage from blood-borne contamination. BBB leakage occurs in a variety of neurological disorders such as Alzheimer's disease.

"High levels of cholesterol are a risk factor for Alzheimer's disease, perhaps by compromising the protective nature of the blood-brain barrier. For the first time, we have shown that chronic ingestion of caffeine protects the BBB from cholesterol-induced leakage," Jonathan Geiger, of the University of North Dakota School of Medicine and Health Sciences, said in a prepared statement.

Caffeine appears to offer protection by helping proteins maintain the tight binding of the cells in the BBB, so they stop unwanted molecules from entering the central nervous system.

The findings also confirm previous studies showing that caffeine protects against memory loss in aging and in Alzheimer's disease.

"Caffeine is a safe and readily available drug, and its ability to stabilize the blood-brain barrier means it could have an important part to play in therapies against neurological disorders," Geiger said.

More information

The U.S. National Institute on Aging has more about Alzheimer's medications.

THURSDAY, April 3 (HealthDay News) -- You may no longer need to remember whether it's "starve a cold, feed a fever" or vice versa. New research suggests you should just eat.

A study of deer mice has found that reducing the amount of food the mice ate impaired their immune system. The findings are published in the May/June issue of Physiological and Biochemical Zoology.

The researchers found that decreasing the amount of food the mice ate by 30 percent significantly decreased the number of B cells in their systems. B cells produce antibodies and maintain immune memory, so an immune system lacking B cells must relearn how to fight infection and disease.

"A 30 percent restriction in food intake doesn't affect body mass and only minimally reduces activity in deer mice, but it eliminates the long-term immune protection provided by antibodies," study co-author Lynn Martin said in a prepared statement. "One wonders whether similar moderate food restriction has comparable immune effects in humans."

Martin and fellow researchers cited previous studies that had found that infections were "more frequent and tend to be chronic in malnourished children." Previous studies have also found that vaccines that provoke B cells to protect the body long-term, such as the vaccine for measles, are less effective among the malnourished.

The authors proposed that future research should be done to learn what specific features of diet (calories, protein, micronutrients) affect immune system function.

More information

The U.S. National Institute of Allergy and Infectious Diseases has more on how vaccines work.