Eating Fish Weekly Is Found

To Slow Aging of the Brain

Eating fish at least once a week is good for the brain, slowing age-related mental decline by the equivalent of three to four years, a study suggests.

The research adds to the growing evidence that a fish-rich diet helps keep the mind sharp. Previous studies found that people who ate fish lowered their risk of Alzheimer's disease and stroke. Fish such as salmon and tuna that are rich in omega-3 fatty acids also have been shown to prevent heart disease.

For the new study, researchers measured how well 3,718 people did on simple tests, such as recalling details of a story. The participants, -- all were Chicago residents age 65 and older -- took the tests three times over six years. They also filled out a questionnaire about what they ate that included 139 foods.

"We found that people who ate one fish meal a week had a 10 percent slower annual decline in thinking," said co-author Martha Clare Morris, an epidemiologist at Rush University Medical Center. "Those who ate two fish meals a week showed a 13 percent slower annual decline."

The study of fish and mental sharpness was posted yesterday on the Web site of the Archives of Neurology and will appear in the journal's December issue.

Japan Successful in Test

Of Supersonic Jet Prototype

Japan's space agency yesterday completed the first successful test of a prototype jet that can fly at twice the speed of sound, three years after an earlier test ended in a fiery wreck in the Australian outback. Kenichi Saito, a spokesman for the Japan Aerospace Exploration Agency, said yesterday's unmanned flight went "as planned."

A breakthrough in supersonic flight could help Japan leap ahead in the aerospace field. The country manufactures components for Boeing but has only a limited domestic airplane industry. Saito said the prototype, a 38-foot-long, arrow-shaped craft developed by Mitsubishi Heavy Industries Ltd., was launched on a rocket and reached a flying altitude of 11 miles before floating back to Earth by parachute.

Yesterday's $10 million experiment marked a crucial step in Japan's plans to develop a supersonic aircraft that could carry 300 passengers between Tokyo and Los Angeles in about four hours.

Walking as Good for Heart as

Moderate Jogging, Study Says

Walking 12 miles a week is enough to improve cardiovascular health, according to a study in the October issue of the journal Chest.

Researchers at Duke University Medical Center found that overweight people who walked 12 miles a week, consumed oxygen more efficiently and gained physical endurance -- both of which reduce the risk of cardiovascular disease, author Brian Duscha said.

Many people find exercise difficult and think that only intense physical activity will improve their health, but that is not the case, said Duscha, an exercise physiologist at Duke.

The Duke researchers studied 133 overweight or slightly obese men and women aged 40 to 65 who did not exercise and had high cholesterol. The participants were told not to change their diet.

Participants were randomly assigned to one of four groups. One group did not exercise at all, while a second did the equivalent of walking 12 miles a week on a treadmill. A third group jogged 12 miles a week and the fourth group jogged 20 miles a week.

The group that jogged 20 miles a week showed more benefits than the groups that jogged or walked 12 miles a week, Duscha said, but there was no statistically significant difference between the group that walked 12 miles a week and the group that jogged 12 miles, the study said.

Researchers Rate Chances of

Major Quake in San Francisco

The San Francisco area has a 25 percent chance of being struck by a magnitude 7 or greater earthquake in the next 20 years, finds a study in the journal Proceedings of the National Academy of Sciences.

Researchers at the University of California at Davis led by John Rundle used statistical forecasting methods to analyze information about the San Andreas Fault, the area's main fault line, and the other faults in the San Francisco area.

Other forecasts, which have predicted a major earthquake along the fault every 40 to 100 years, do not account for interaction of the San Andreas with other faults, said Rundle, a geologist and professor.

The San Francisco area has a 50 percent chance of a large earthquake in the next 45 years, and a 75 percent chance in the next 80 years, the study found.

-- From News Services

Japan's supersonic jet prototype landed in the Australian outback after a test flight.