We watched my wife’s uncle age to 102. Only in the last year did he have any significant medical problems. He was very hard of hearing and was less able to move mountains in his last years, but he did ask for his 98th birthday to have a bowling party. We watched, amazed, as he walked up to the line, swung the ball back and forth, and let it go. It moved so slowly that we assumed it would end up in the gutter. But no, he got a spare!
Perhaps we should not have been surprised. He was always on the go, ate healthy meals, never smoked, and enjoyed being with friends.
He always seemed calm and collected, so on his 101st birthday, I asked how he had managed his stresses — his ship, the Canberra, was torpedoed during WWII with the loss of many of his buddies, and he was nearly killed. He had lost his daughter to cancer when she was forty, and his wife to cancer when she was 67. Yes, he had grieved greatly, but somehow, he was resilient and came back strong each time. He had been very sad but lived through his grief and always appeared unperturbed. “Well,” he said, “I guess I just let stress roll off my back.”
Organs decline about 1% per year.
One of the most important things that happens with aging, sort of like a car, “old parts wear out.” Most organ functions decline by about one percent per year. Of course, there is great variation from person to person, year to year, organ to organ, but 1% is a pretty good average to consider. We usually think of a person being in their prime through at least age 60. In many ways, that is correct, but you may be surprised to learn that the 1% decline starts in early adulthood and continues throughout life, speeding up as we age. Fortunately, most of our organs have significant redundancy so that we can tolerate these declines without any appreciable impact. But eventually, the decline may get to the point where we have a functional impairment that can be serious or at least impair our day-to-day activities.
I recently turned 84. I don’t feel “old,” but I do know I can’t do everything I used to do, or at least not as quickly. My hearing is less; my vision is reduced. My muscle mass and strength are definitely much less than they were in the recent past. My balance is OK, but not as good as it used to be, and so on. It has been a set of changes that came slowly at first but are now progressing faster. I always enjoyed splitting wood for the fireplace. I kept a woodshed filled with wood split and logs drying for a year before splitting. As time went on, I realized that I couldn’t keep at it for as long before wanting to take a break. As one friend in his early 80s told me, “I was fine until about age 78, and then it seemed that the aging process was suddenly there and moving fast.” Those declines, developing “under the radar” for decades, had accelerated and become overt.
The 1% Per Year Decline, Author’s image
Hearing decline begins at about age 25 but is not noticed until much later. Many of you will need reading glasses by age 40, even though you have had excellent vision for years; cataracts may occur later. Balance starts its inevitable decline early, although it, too, will not be noticed until much later. Meanwhile, internal organs, including the heart, lungs, and kidneys, are slowly declining, and so too is brain function, especially cognition.
This normal aging process of old parts wearing out is universal and is progressive, but you can slow it and sometimes reverse it, at least partially. Let’s use bone mineral density (BMD) as an example. BMD is easily measured to demonstrate the sturdiness of our bones — how strong they are. We start life with cartilage rather than bones. As we grow from toddlers to children to teenagers, calcium and other minerals, along with a protein-collagen matrix, are laid down in our bones, and they become increasingly strong, reaching a peak around the age of twenty. Once that age and that peak are reached, it can’t go up any further — that’s it. Then there is a plateau, and at about age thirty to forty it starts to decline at a rate of about 1% per year. At age twenty, men’s bone mineral density is, on average, higher than women’s.
Nevertheless, for women as for men, the decline is about one percent per year. Menopause changes this; the rate of loss increases to perhaps three percent per year for a few years and then returns to the one percent average decline until reaching osteopenia and then osteoporosis. There are three important points to consider. If you live long enough, your bone mineral density will decline to a level where, if you fall, a bone fracture becomes more likely. Since women start at a lower level and because they have this increased loss of BMD during menopause, they’ll reach that fracture threshold in life earlier than men. Since women tend to live longer than men, in total, more women than men will have a fracture at some point in their lives. We might just say this is one of the risks of living longer.
But why will you fall? Because your balance mechanism is likewise declining, and your muscle mass and strength are not as capable of “catching” your fall. The three combine together in a very negative manner!
Muscle mass and strength decline in a similar fashion, resulting in what doctors call sarcopenia. Most people lose perhaps 30% of their muscle mass between ages 50 and 70, and the loss continues at an even faster rate thereafter. Older individuals who exercise find it takes more effort to maintain their muscle mass and strength, but regular exercise and good nutrition have a significant beneficial impact and slow the process considerably.
Cognitive function is another example; your brain loses some of its abilities as you age. Cognitive abilities and brain volume do not decline in lockstep but do have a clear relationship. A fascinating study published in the journal Nature in April 2022, pulled together 123,984 MRI scans taken at over 100 institutions from 101,457 individuals ranging from 115 days post-conception to 100 years of age — from fetuses to centenarians. At the age of three years, the brain had reached 80% of its maximum size. The gray matter, which consists of the actual brain cells, reaches its maximum by about age 6, whereas the white matter, the inner connections between brain cells, does not reach its peak until the late 20s. The decline in brain volume thereafter is slow but accelerates after about age 50. These changes can be seen in the figure, which shows the growth trajectories of gray and white matter. The charts show volume (in mm3) across age, beginning before birth and ending at about 100 years.
If you are over 65, you have probably noted that you can’t memorize as well, recall names as quickly, etc. When I was in medical school, memorization was relatively easy; not so today! This is normal. This loss of cognitive function over time should not be confused with the disease Alzheimer’s. Nearly everyone who lives long enough will suffer from some cognitive decline, but only some will develop Alzheimer’s. As with BMD, you reach your peak cognitive function around age twenty; it plateaus for about 10 years, then starts that slow decline. Given the great redundancy in your brain, it is not noticeable for some time. Eventually, you reach a functional threshold where your cognitive function begins to impair your ability. This becomes more apparent when an older person is engaged in highly technical activities, very fast-paced activities, or stressful situations (emotional, physical, or health-related). Those cognitive challenges are less apparent in highly familiar situations.
This 1% annual loss is normal. No, it is not an exact number, nor is it the same for every person or every organ, nor is it exactly 1% in the same person at all times. But 1% is a good proxy for what is happening throughout your body throughout adulthood and into your elder years.
Slowing the aging losses
Here are some suggestions to slow that steady decline in functions. If you start at age twenty with very strong bones (i.e., a high BMD), then you have a longer way to go down before reaching that level of potential bone fracture from a fall. Perhaps too late for you if you are older, but encourage your children and grandchildren to eat a good diet, play/exercise daily, preferably outdoors, manage their stress, and get a good night’s sleep. And for their brains, do just the same (quality food, plenty of exercise, sound sleep, and managed stress) as for their other organs. Then, continually challenge their brains with new learning. Those with more years of schooling will start out with greater reserves, so the 1% decline will take much longer to cause difficulties. Muscle mass and strength are similar. Encourage them to build it up now as a teen. No need to be a muscled bodybuilder, but regular exercise and a good diet will mean more strength at the start of that long decline.
Most people seem to accept that, with age, comes a decline in function. “That is just what happens when we get older.” They may not like it, but they do not realize that they can substantially modify the downhill course. You can slow this continuing loss of body functions, including cognitive decline, and you can start at any age. It is never too late. It is not hard to do, and it does not cost money, but it does take time and persistence. It is all about how you move, what you eat, how you manage chronic stress, get adequate sleep, avoid tobacco, not too much alcohol, plus challenge your brain and keep socially engaged.
Stephen C Schimpff, MD, MACP, is a quasi-retired internist, professor of medicine, former CEO of the University of Maryland Medical Center, and author of Longevity Decoded — The 7 Keys to Healthy Aging, and is co-author with Dr. Harry Oken of BOOM — Boost Our Own Metabolism
