ROCHESTER, Minn., June 24 Here are highlights from the June issue of Mayo Clinic Health Letter. You may cite this publication as often as you wish. Reprinting is allowed for a fee. Mayo Clinic Health Letter attribution is required. Include the following subscription information as your editorial policies permit: Visit http://www.HealthLetter.MayoClinic.com or call toll-free for subscription information, 800-333-9037, extension 9PR1.
New Scanning Technology Offers Better Picture of Critical Brain Functions
Researchers are taking MRI to a new level that offers a better picture of vital brain functions, according to the June issue of Mayo Clinic Health Letter.
MRI is a standard imaging tool that uses magnetic fields and radio waves to generate images of the body. It's particularly helpful in diagnosing brain tumors, but MRI doesn't clearly convey the risks of removing the tumor.
A new tool, functional magnetic resonance imaging (fMRI), gives a clearer picture of the brain in action and what brain tissue is relevant to accomplishing a given task, such as raising a hand or reading a sentence. Basically, fMRI detects changes in the brain's blood flow that occur when performing specific tasks. The result is a color-coded image that shows surgeons areas of the brain where permanent injury should be avoided. Although there's general understanding of where these important brain centers are, they vary by individual.
So far, fMRI scans mainly have been used at major medical centers as a research tool. Some early studies indicate that its use prior to surgery is associated with a significant reduction in complication rates, particularly when tumors are close to the brain's language centers or parts of the brain responsible for movement.
Researchers also are using fMRI to better understand psychiatric disorders, though it remains difficult to use this technology to identify disorders such as schizophrenia, attention-deficit/hyperactivity disorder and autism. In another research area, fMRI is being used to determine how mild cognitive impairment might evolve in the brain. People with mild cognitive impairment are considered at increased risk for dementia.
Obesity-Related Cancer on the Rise
As Americans' collective waistline has continued to expand, so has the prevalence of obesity-related cancer.
According to the June issue of Mayo Clinic Health Letter, an estimated 14 percent of cancer deaths in older men and 20 percent in older women can be attributed to excess body fat. It's not fully understood why excess body fat increases the risk of cancer.
Insulin -- Obesity and inactivity generally lead to higher levels of insulin circulating in the blood. Excess insulin is believed to fuel the growth of cancer cells. In addition, it increases circulating levels of other hormones that likely play a role in cancer development and growth, such as estrogen.
Estrogen -- Adding to insulin's influence on estrogen levels, fat tissue also produces this hormone. Estrogen levels are 50 percent to 100 percent higher in postmenopausal women who are overweight versus those who are lean. It's believed that this alteration increases the risk of estrogen-sensitive cancers such as certain types of breast cancers.
Immune system -- Excess fat is thought to release proteins that may suppress the immune system and increase inflammation. Both may play a role in cancer development and progression.
Other risks of obesity -- Obesity-related problems such as acid reflux, high blood pressure, gallstones and fatty liver may damage tissues of the esophagus, kidney, gallbladder and liver, respectively. This may set the stage for cancer development.