Current Topics and Discussions

USDA Pushes Ahead on Research of B Vitamins and Their Impact on Aging Brains | 08/18/2010

Ongoing research takes a closer look at role these nutrients may play in preventing decline in brain function of elderly; depression in women

B vitamins–B-6, B-12 and folate–all nourish the brain. Ongoing research indicates lower levels of these B vitamins may enhance dementia, cognitive decline and even depression in senior citizens.

The research has been encouraged by the Department of Agriculture (USDA), because the agency feels much remains to be discovered about the relation between these essential nutrients and brainpower.

According to Lindsay H. Allen, USDA nutritionist, the research is needed because many studies of B vitamins and brain function have given inconsistent or conflicting results.

Allen is director of the Agricultural Research Service (ARS) Western Human Nutrition Research Center in Davis, Calif. ARS is the chief intramural scientific research agency of USDA. Scientists from the University of California-Davis (UCD) and the UCD Medical Center also are collaborating in the research.

Allen has collaborated in ongoing research that has taken a closer look at the role these nutrients may play in preventing decline in brain function.

The investigations, led by Mary N. Haan of the University of California-San Francisco, are part of the multiyear Sacramento (Calif.) Area Latino Study on Aging, or “SALSA.” Begun in 1996, the study attracted nearly 1,800 Hispanic seniors, ages 60 to 101, as volunteers.

An analysis of volunteers’ blood samples showed that lower levels of one B vitamin, folate, were associated with symptoms of dementia and poor brain function, also called “cognitive decline,” as determined by standard tests of memory and other factors. The impairments were detectable even though less than 1 percent of the volunteers were actually deficient in folate.

Low Levels of Folate and Depression in Women
In women, but not men, low levels of folate were associated with symptoms of depression. In fact, female volunteers whose plasma folate levels were in the lowest third were more than twice as likely to have symptoms of depression as volunteers in the highest third. That finding provided new evidence of an association between lower blood folate and depression. Depression is already known to affect brain function.

In research with vitamin B-12, the SALSA team also determined that a protein known as holoTC, short for holotranscobalamin, might be key to a new approach for detecting cognitive decline earlier and more accurately.

The researchers have published these and other findings, beginning in 2003 and continuing through this year, in the American Journal of Clinical Nutrition, Clinical Chemistry and Laboratory Medicine, The European Journal of Clinical Nutrition, The Journal of Nutrition, and The Journal of Nutrition, Health, and Aging.

Source: USDA, August 17th, 2010

New Test May Encourage More to Be Screened for Colorectal Cancer | 08/12/2010

A new option for non-invasive colorectal cancer testing may encourage some people who avoid screening for the deadly disease to be tested, according to Indiana University researchers.

A study published in the December 23 issue of the New England Journal of Medicine reports that a non-invasive test for DNA mutations present in stool detects colorectal cancer more than half of the time — far better than the standard non-invasive method, fecal occult (hidden) blood stool testing.

The study, conducted at 81 sites, reports that the fecal occult blood test found only 13 percent of colorectal cancer while the new stool DNA test detected 52 percent of the cancers.

Neither test approaches the detection rate of colonoscopy, an invasive procedure which is presumed to find all colon cancer. Many people, however, are unwilling to undergo a colonoscopy, an uncomfortable procedure that requires anesthesia.

“A simple, non-invasive test that detects tumor-specific products with reasonable sensitivity and specificity might overcome barriers to screening among persons who are not willing to have a more invasive test, such as colonoscopy,” said Dr. Thomas Imperiale, professor of medicine at the Indiana University School of Medicine.

“There are many reasons why people don’t get screened for colon cancer,” said Dr. Imperiale. “Some individuals do not want colonoscopy because of discomfort despite conscious sedation, its inconvenience, or its risk for complications; others are unwilling to smear stool samples on a card for the occult blood test every year.”

The stool DNA panel test, which requires a single sample expelled from the body directly into a container, gives people who are not getting screened with any of the currently available methods, another noninvasive option

Source: MedicalWeek Staff, December 23rd, 2004

Ninety Percent of Stroke Risk due to 10 Risk Factors | 06/23/2010

A large international study has found that 10 risk factors account for 90% of all the risk of stroke, with high blood pressure playing the most potent role.

Of that list, five risk factors usually related to lifestyle — high blood pressure, smoking, abdominal obesity, diet and physical activity — are responsible for a full 80% of all stroke risk, according to the researchers.

The findings come the INTERSTROKE study, a standardized case-control study of 3,000 people who had had strokes and an equal number of healthy individuals with no history of stroke from 22 countries. It was published online June 18 in The Lancet.

The study — slated to be presented Friday at the World Congress on Cardiology in Beijing — reports that the 10 factors significantly associated with stroke risk are high blood pressure, smoking, physical activity, waist-to-hip ratio (abdominal obesity), diet, blood lipid (fat) levels, diabetes, alcohol intake, stress and depression, and heart disorders.

Across the board, high blood pressure was the most important factor, accounting for one-third of all stroke risk.

“It’s important that most of the risk factors associated with stroke are modifiable,” said Dr. Martin J. O’Donnell, an associate professor of medicine at McMaster University in Canada, who helped lead the study. “If they are controlled, it could have a considerable impact on the incidence of stroke.”

Controlling blood pressure is important, he said, because it plays a major role in both forms of stroke: ischemic, the most common form (caused by blockage of a brain blood vessel), and hemorrhagic or bleeding stroke, in which a blood vessel in the brain bursts.

In contrast, levels of blood lipids such as cholesterol were important in the risk of ischemic stroke, but not hemorrhagic stroke.

“The most important thing about hypertension is its controllability,” O’Donnell said. “Blood pressure is easily measured, and there are lots of treatments.”

Lifestyle measures to control blood pressure include reduction of salt intake and increasing physical activity, he said.

He added that the other risk factors — smoking, abdominal obesity, diet and physical activity — in the top five contributors to stroke risk were modifiable as well.

High intake of fish and fruits, for example, were associated with a lower risk of stroke, according to the study.

The researchers pointed out several potential limitations of the study, including the sample size, which they said “might be inadequate to provide reliable information” about the importance of each risk factor in different regions and ethnic groups.

Many of the same risk factors have cropped up in other studies, but this is the first stroke risk study to include both low- and middle-income participants in developing countries and to include a brain scan of all participating stroke survivors, according to the researchers.

The countries joining in the study were Argentina, Australia, Brazil, Canada, Chile, China, Colombia, Croatia, Denmark, Ecuador, Germany, India, Iran, Malaysia, Mozambique, Nigeria, Peru, Philippines, Poland, South Africa, Sudan and Uganda.

The INTERSTROKE study confirms that high blood pressure “is the leading cause of stroke in developing countries” as well as developed nations, Dr. Jack V. Tu, of the University of Toronto, wrote in an accompanying editorial. He added that it highlighted the need for health authorities in those countries to develop strategies to reduce high blood pressure, salt intake and other risk factors.

A second phase of the INTERSTROKE study is underway, with researchers looking at the importance of risk factors in different regions, ethnic groups and types of ischemic stroke. They’ll also study the association between genetics and stroke risk. The researchers plan to enroll 20,000 participants.

Dr. Larry B. Goldstein, director of the Duke Stroke Center, noted that the study underscored what’s already known about stroke risk.

“The bottom line is that the risk factors for low- and middle-income countries seem to be pretty similar to those of Western countries,” Goldstein said. “The findings reiterate the importance of attention to lifestyle factors in stroke risk — diet, smoking, physical activity.

Source: HealthDay News, June 18th 2010

Two Types of Hypertension Drugs Appear to Increase Risk of Developing Type 2 Diabetes | 06/10/2010

Two types of drugs used to treat hypertension, diuretics and beta-blockers, appear to increase a person’s chances of developing type 2 diabetes, according to Harvard researchers.

But two other types of hypertension drugs, calcium channel blockers and ACE inhibitors, were not linked to development of type 2 diabetes, the researchers reported in the May issue of the journal Diabetes Care.

The researchers undertook their study, using data from studies that followed three large groups of women and men, in an effort to clarify conflicting findings as to the relation between the use of different classes of antihypertensive medications and the risk of type 2 diabetes.

“Thiazide diuretic and beta-blocker use were independently associated with a higher risk of incident diabetes,” the researchers found. “Increased surveillance for diabetes in patients treated with these medications may be warranted.”

The risk of developing diabetes for people taking thiazide-type diuretics was 20 percent higher for older women, 45 percent higher for younger women, and 36 percent higher for men, the researchers found.

And older women taking beta-blockers for hypertension had a 32 percent higher risk of developing diabetes than those not taking beta-blockers, while for men the risk was 20 percent higher.

“ACE inhibitors and calcium channel blockers were not associated with risk,” the researchers reported.

Source: Medical Week staff, May 19, 2006

New Research Adds to Suspicion That Herpes Is Linked to Alzheimer’s Disease | 05/30/2010

New findings by University of Rochester researchers, published online in the journal Neurobiology of Aging, add scientific support to the longtime suspicion by some scientists that herpes somehow plays a role in bringing about Alzheimer’s disease.

A form of the ApoE gene known as ApoE-4, known to be a major risk factor for Alzheimer’s disease, appears to put out the welcome mat for the virus that causes cold sores, allowing the virus to be more active in the brain compared to other forms of the gene, according to the researchers.

ApoE-4, which after advanced age is the leading known risk factor for getting Alzheimer’s disease, was linked by the researchers to herpes simplex 1 or HSV, which infects more than 80 percent of Americans and causes cold sores around the mouth.

The findings from a group at the University of Rochester Medical Center show that the particular form of the gene that puts people at risk also creates a fertile environment for herpes in the brain, allowing the virus to be more active than other forms of the ApoE gene permit.

“This work raises the question whether herpes in concert with ApoE-4 increases the risk of Alzheimer’s disease. The data suggests that ApoE-4 may support the ability of HSV to be a more virulent pathogen,” said Dr. Howard Federoff, professor of Neurology, Medicine, and Microbiology & Immunology.

The findings, based on measurements of the activity levels of the herpes virus in the brains of mice with different forms of the human ApoE gene, bring together several lines of research that have pointed toward a possible role for herpes in Alzheimer’s disease.

Source: Medical Week staff, week of Jan. 1, 2007