(Editor's Note: This article originally appeared in Nutrition Health Review, Issue #25.)

PLEASANT MEMORIES are always more available to us than unpleasant ones. Perhaps that is why older people often dwell upon the happier past.

Memory thrives on emotions and stimulation. Every memory is encased in its own emotional cocoon. That is why we can often recapture memories by feelings that accompanied them. Music, for example, usually triggers immediate recall.

THE MEMORY MACHINE sometimes needs fine tuning. Unless you are born with a phenomenal brain that actively remembers everything it encounters, diligence and attention are needed to keep -memory efficient.

We cannot remember what we do not think about. It must register aurally and visually. Distraction is the enemy of remembrance. Memory responds to input best when one is mentally relaxed and listening carefully, making visual "notes" for further reference.

Some researchers say that people with hearing loss in the right ear have more difficulty remembering. What is heard through the right ear, it has been said, is better remembered than what is heard through the left ear.

IS THE AGING PROCESS the "trigger" of diseases, or do diseases hasten the aging process? The answer to life extension lies in limiting the number of illnesses we endure, declare researchers. Every time we suffer a cold or other infectious disease, to some extent the immunological system loses its potency, despite the fact that some diseases stimulate the development of antibodies.

Degenerative diseases, although they are not directly involved with fighting off invasive infections, damage the vital organs of the body. The diabetic pancreas, the arthritic joints, the pressured kidney are all depositories of defensive armies. There is therefore a link between degenerative diseases, infectious diseases and the aging process.

THE BRAIN DOES DECREASE in weight as we grow older. It doesn't necessarily follow that there is a decrease in brain cells. The primary reason for such changes could be a significant decrease in extracellular space, says Dr. Kenneth R Brizzee of the Delta Regional Research Center in Covington, Louisiana. Rich, nutritious flow of blood to the brain may preserve the integrity of the brain cells despite the loss of volume.

Experimentally it has been proven that cells transplanted from old brains to young have survived for long periods of time, often living longer than their original donors.

THE FREE -RADICAL THEORY of aging implicates chemical fragments that enter into reactions with other chemical compounds in the cell structure. They are frequently generated from unhealthful foods, tobacco smoke, polluted air, impure water. Lipid peroxidation (the combination of fats, hydrogen and oxygen) occurs when free radicals react with unsaturated fatty acids (such as those found in hydrogenated vegetable fats). Margarine and fried foods are in that category.

To counteract the effect of free-radical molecules the most effective antioxidants are Vitamins E and C. The trace element selenium has also proven to be effective.

Researchers discount the theory that free radicals are the only cause of premature aging. The critical factor that leads to deterioration, most authorities agree, is the loss of capacity for cell division in tissues such as brain, heart, and muscles. These inevitable changes can be slowed down by dietary manipulation.

OVEREATING IS A FACTOR in reduced longevity. Experiments have revealed that the heavier the animal, in relation to its natural sizeweight, the shorter the life span.

Interviews with centenarians have revealed that they were predominantly modest eaters. Their choice of foods, either by circumstance or economics, were limited in the amount of protein they ingested.

The low-calorie diet produced less chronic diseases. Mary J. Tucker, a British researcher, reports that eating less may prevent cancer, if the food selections are well-balanced and high in vital nutrients.

THAT STRESS CAN HASTEN DEATH is generally an accepted theorem. Statistics show that the death rate from heart attacks is exceptionally high on the three national holidays: Independence Day, Christmas Day, and New Year's Day. Monday also heads the list.

Why should they also be statistically low on Memorial Day, Labor Day, and Washington's Birthday? (Reported by the National Heart and Lung Institute, Department of Epidemiology, Bethesdá-, Maryland).

BE WARY OF THYROID FUNCTION TESTS, says Dr. Broda O. Barnes, a Colorado physician. He has been treating thyroid disorders for almost fifty years and agrees that stressprone individuals suffer from thyroid deficiency. However, he cautions that thyroid functions tests are inadequate because they measure the amount of thyroid hormones in the bloodstream rather than in the cells.

Dr. Barnes prefers to use the measurement of body temperature as an indication of thyroid deficiency, because hypothyroid patients seem to have below-normal temperatures. Any person with a chronically low temperature is suspected of being thyroid deficient, he declares.

PERPETUAL STRESS produces lesions in the arterial walls. It is into these lesions that plaque, fats, connective tissue proteins, clotted blood, and calcium settle.

Improper diet, cigarette smoking, physical inactivity together with other stressful elements combine to cause atherosclerosis, and hastened aging. (Hardly anything is said about tobaccoleaf protein induced allergy, an area that should be "wide-open" for aging related stress).

REJUVENATION THERAPIES have their advocates. Many are absolute frauds; others have attained a level of respectability. Gerovital-H3, the drug compounded by Ana Asian, the Romanian physician, has attained no accepted scientific validity. Whether this geriatric "cure" will be proven effective to the satisfaction of scientific researchers is a matter for the future. Its principal ingrethents, the vitamin PABA (paraaminobenzoic acid) and the metabolite DEAE (diethylaminoethanol), are eliminated from the body when not needed. PABA is especially useful in preserving the integrity s? the nervous system.

LIVING TO 100 may seem a far-fetched dream. But if you were able to go back in time and speak to the average Roman, who only had a life expectancy of 20 to 30, he would be incredulous to be told that 20th century humans were able to stretch their parameters to a life expectancy of 76 for American women. He would also blink at the suggestion that improved sanitation, nutritious foods, vitamin supplements and knowledgeable emergency medical aid could take the human range beyond 100. Our infant survival rate would be beyond belief.

IS THERE YOUTHFULNESS AMONG THE AGED? Consider Charles Chaplin, who lived in comparatively good health into his late 80's; George Bernard Shaw who lived into his 90's; Cervantes completed Don Quixote at age 70; Goethe finished Fause at 83, Sophocles was in his late 80 's when he finished his plays of the Oedipus cycle. Bertrand Russell, Adolph Zukor, and Oliver Wendell Holmes remained active into their 90 's, performing their usual business and artistic functions capably. Pablo Picasso painted into his late 80 's and the Renaissance Titian was busy painting up to his death at 99.

NOISE IS AN UNDERESTIMATED POLLUTANT. It is a nuisance and a health menace. Gastric juices react to high levels of noise, adrenal hormones are discharged, skin changes have been known to take place and high blood pressure can be induced.

Loud noises contribute to the deterioration of the ear's ability to hear. The contemporary fad for highly amplified music is creating hearing difficulties in numbers that are compounded with each generation.

Not only do high decibels of sound hasten deafness, but the long-term wear and tear acts as a stressor. Rapid aging is definitely associated with the damage inflicted upon the nervous system, and the aural organs by excessive, persistent noise.

TO LIVE LONGER, youthfully, we must develop a science of health that preserves a wellbalanced neuroendocrine system, a vigilant and strong immunological system, and efficient cellular repair system. Altogether an enhanced ability to regenerate dying cells, weary tissues and tired organs. Drugs will not accomplish that goal. Nutrition and mental attitude may.

THE HEART DOES NOT WEAR OUT WITH AGE. In a report presented to the American Heart Association, Dr. Gary Gerstenblith of the Johns Hopkins University School of Medicine, Baltimore, said that he and his colleagues compared the cardiac output of 61 men and women, ranging in age from 21 to 79.

They found that older people who exercise can increase cardiac output just as younger people do. There is a difference in how the older cardiac systems work, he said, but not in their ability to function.

"In younger people," he explained, "the heart increases its output by beating faster. In older people, output is increased by pumping more blood with each beat rather than by greatly increasing the rate of heartbeat."

The subjects were all healthy, active people who were aware of the need for proper diet and adequate exercise. One implication of the study is that keeping active and taking care of oneself is beneficial in later life. Aging does not automatically diminish cardiac fitness.