It is often said that death defines life, or said another way, it is death that gives meaning to life. We all face death, but unfortunately, not all humans have to deal with ageing (or aging if you prefer). Too many young people have their lives cut short by wars, disease, drugs, violence, etc., before they have a chance to age. Another common saying is that youth is wasted on the young, but that’s a topic for another day.
Most humans will grow old and experience ageing, which is usually not fun, as many older individuals know and will tell you. But exactly why our bodies change as we age is not fully understood yet, but we are learning more about ageing every day. For example, last November the New York Post had an article about a study done in Tel Aviv. Researchers there placed middle aged volunteers into a hyperbaric oxygen chamber for 90 minutes a day, five days a week, for three months. They found that on the biological level, the volunteers had their cellular age reversed by 25 years.
Ageing occurs on a cellular level because of both programmed, genetic changes in cells and damage to DNA. Both processes cause DNA mutations to occur as cells divide. Cellular division occurs constantly from conception to death because cells themselves die and must be replaced. However, research has shown that some human cells, for example some cancer cells, stem cells, and germ cells, when grown in culture medium do not die. Leonard Hayflick, a researcher at UCSF who wrote How and Why We Die, found that human cells in culture will divide up to 50 times and then stop dividing, becoming what are called senescent cells.
Research has found that ageing occurs on a cellular level for primarily two reasons – the shortening of telomeres, also called the “Holy Grail” of ageing, and the formation of senescent cells. Telomeres are extensions on the ends of chromosomes that protect against DNA replication errors, or mutations. The shorter the telomere, the more likely are DNA mutations.
There are examples of “immortal” organisms in nature. Some bacteria fission to make daughter cells, strawberries grow runners to make clones of themselves, and hydra, small, fresh-water organisms, regenerate themselves. In 1987, Rowe and Kahn defined “successful ageing” as 1) freedom from disease and disability; 2) high cognitive and physical functioning; 3) social and productive engagement. As birthrates drop, the developed world is getting older. Currently 11% of the population is 60 and older, and it is estimated that number will be 22% by 2050.
Ageing in humans causes many changes to the body. Blood vessels stiffen, bones shrink and lose density, muscles lose strength, endurance, and flexibility, the bladder becomes stiffer, skin becomes thinner, less elastic, and bruises more easily, and metabolism slows, to name a few of the changes. Recommendations to” successfully” age include getting daily exercise, eating a healthy diet with plenty of fruits and vegetables, getting seven to nine hours of sleep a night, managing stress, managing your weight, avoiding smoking, and keeping your mind active by reading, doing puzzles (crosswords are my favorite), getting a hobby, or playing an instrument.
By Peter Galvin, MDBLOG COMMENTS POWERED BY DISQUS