Risk Seen in Even Slightly High Blood Pressure
Even slightly elevated blood pressure--in the range physicians call high normal--significantly increases the risk of heart disease, a new study has found.
Researchers have long known that greater elevations are a significant risk factor for heart disease, but the new study indicates that anything above normal represents some risk. No studies have shown that reducing high-normal blood pressure decreases risk, however, and scientists are not yet prepared to suggest that people in this range take drugs to lower it. But they do urge drug-free efforts, such as exercise, restriction of salt intake and weight loss.
Blood pressure readings consist of two numbers: the higher systolic pressure and the lower diastolic pressure, both measured in millimeters of mercury. Any reading below 130/85 is considered normal; any reading over 140/90 is considered high.
But the high normal readings between those two limits--which affect about 13% of the U.S. population--have generally been considered a gray area, and physicians do not usually recommend treatment.
Dr. Ramachandran Vasan of the Boston University School of Medicine studied 6,859 people in the Framingham Heart Study--a study started in 1948 to look at potential causes of heart disease--to look for links between blood pressure and heart disease.
He and his colleagues reported in the Nov. 1 New England Journal of Medicine that, over the 12 years of the study, the risk of heart disease was about 2.5 times higher for those with high-normal blood pressure. The risk increased with age.
The researchers cautioned, however, that people with high-normal blood pressure also tended to have other risk factors for cardiovascular disease and that the influence of those factors could not be completely eliminated.
Vitamin Deficiency Tied to Diabetes
A new Finnish study suggests that giving infants supplements of vitamin D sharply decreases the risk of Type 1 diabetes, also known as juvenile-onset or insulin-dependent diabetes.
Some smaller previous studies had suggested such a link, and the new findings hint strongly that vitamin D deficiencies may play a crucial role in development of the disease.
But experts cautioned that the study was conducted in northern latitudes where the subjects had minimal exposure to sunlight--which is crucial for triggering normal vitamin D activity. It is not clear whether the supplements would be useful in a population that is more exposed to sunlight, such as that of the United States.
Dr. Elina Hypponen of the Institute of Child Health in London and her colleagues studied all 12,058 live births that occurred in Oulu and Lapland, in northern Finland, during 1966, monitoring them until the end of December 1997. The team reported in the Nov. 3 Lancet that infants who received regular daily supplements of about 2,000 international units of vitamin D during the first year of life were 80% less likely to develop diabetes than those receiving smaller doses or none.
Vitamin D has a mild immuno-suppressive effect, and researchers speculate that it suppresses the autoimmune attack on insulin-secreting pancreas cells that cause diabetes.
End of ‘Gate-Keeping’ Produces Little Change
Ending gate-keeping by health maintenance organizations does not necessarily lead to an increase in visits to specialists, according to Boston researchers.
Most HMOs require that clients first visit a general practitioner if they want to see a specialist and that only the physician can refer them, a process called gate-keeping that is thought to be necessary to hold costs down. Neither patients nor physicians like the process, however.
In 1998, Harvard Vanguard Medical Associates responded to patient and physician concerns by eliminating gate-keeping. Dr. Steven Pearson of Harvard Medical School and his colleagues studied the effects of the change. They examined doctor visits made by 60,000 patients before the change and 30,000 afterward.
The team reported in the Nov. 1 New England Journal of Medicine that, on average, patients visited their primary-care physician 1.21 times per six-month period before the change and 1.19 times after it. But the average number of visits to specialists both before and after the change was 0.78 per six months. “The bottom line is that in this kind of system, you can open access to specialists without breaking the bank and without creating havoc,” Pearson said.
Vitamin C Supplements Said to Cut Cancer Risk
Vitamin C supplements reduce the risk of some types of stomach cancer, perhaps by inhibiting formation of cancer-causing chemicals in the stomach, according to researchers from Yale University.
Dietary nitrites, found in smoked and cured foods, can trigger cancers when they are oxidized by normal processes in the stomach, and vitamin C is thought to prevent that oxidation.
Dr. Susan Mayne and her colleagues at Yale and the National Cancer Institute studied 1,095 Americans diagnosed with cancer of the esophagus or stomach plus 687 Americans without cancer. They reported in the October issue of Cancer Epidemiology Biomarkers and Prevention that people taking the supplements had a 40% lower risk of cancer in the middle and lower parts of the stomach.
Link Between Sleep and Learning Disputed
Your mother was wrong: Sleep is not essential to learning, according to Dr. Jerome Siegel of UCLA.
Many researchers have argued that rapid eye movement (REM) sleep, or dreaming, plays a crucial role in memory formation, but a growing body of evidence contradicts that belief, Siegel reported in the Nov. 2 Science.
Humans taking drugs called MAO inhibitors, for example, lose REM sleep for months or even years with no effect on memory. Humans with brain damage that prevents REM sleep also have normal memory, he said. Animals like the duck-billed platypus that have large amounts of REM sleep are not particularly bright; animals considered intelligent, such as whales and dolphins, have little or none.
“Sleep loss interferes with concentration,” Siegel said. For this reason, cramming for exams during periods of sleep loss is not a good academic strategy. Similarly, taking exams while sleepy will interfere with performance. However, it does not appear that sleep is necessary for memory formation.
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Medical writer Thomas H. Maugh II can be reached at thomas.maugh@latimes.com.
