Normal Aging – A Steady Loss of Organ and Process Function

The percentage of the population that will be “elderly” is rising fairly dramatically. In 1900 only four percent of the population was over 65 and only one percent over 75. By 1950 it was eight and three percent, respectively. By 2000 it was thirteen and five percent and now it’s about fourteen and six percent. By 2030 it will be substantially more again.

There are many different concepts about aging but for our purposes we’ll consider aging gracefully or perhaps aging wisely. Most people would prefer to have a long life with the proviso that it is with good health while having some element of fun along the way. That will be the theme of these articles.

Older individuals have multiple age related impairments and they tend to have multiple chronic illnesses. The care of these illnesses is all too often far from ideal. America has the resources but healthcare delivery is dysfunctional at best. And of course we know that health care costs are very high. One of the keys is really good comprehensive primary care which all too many Americans just do not have. The other key is lifestyle modifications; I’ll deal with the latter in some detail in the articles to follow. 

As we age, 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 in this but that is a pretty good average. The decline starts at about age forty and probably much earlier and continues throughout life. Fortunately most of our organs have a huge redundancy and so we can afford these declines without any level of illness. But at some point the decline may get to the point where we have a functional impairment that can be serious.

Hearing decline begins at about age 25 but is not noticed until much later.  Many will need reading glasses by age 40 even though having excellent vision for years; cataracts will occur later.  Balance, often not noticed until later, starts its inevitable decline early as well. Meanwhile internal organs including 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, is progressive, and is irreversible, at least as we know of it today. 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 out in life with cartilage rather than bones but as we grow as toddlers, then as children, then as 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 at 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 forty it starts to decline at the one percent per year rate.   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 that is one of the risks of living longer.

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 again to the one percent average decline until reaching osteopenia and then osteoporosis. There are three important points to be made here. If we live long enough, our bone mineral density will decline to a level where if we 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.

Cognitive function is another example; our brain loses some of its abilities as we age.   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 the disease known as Alzheimer’s. As with BMD, we reach our peak cognitive function around age twenty; it plateaus for about ten years and then starts the slow decline. Given the great redundancy in our brains, it is not noticeable for some time. [Figure modified from Science Magazine] Eventually we reach a functional threshold where our cognitive function begins to impair our ability. This becomes more apparent when an older person is engaged in highly technical activity, in very fast paced activities, or in stressful situations (emotional, physical or health related). Those challenges to cognition are less apparent when in highly familiar situations. 

 

Muscle mass and strength decline in a similar fashion resulting in sarcopenia. Most people lose perhaps 30% of their muscle mass between ages 50 and 70. [Figure modified from the Buck Institute] Individuals that exercise find it takes more effort to maintain their muscle mass and strength but regular exercise and good nutrition have a significant beneficial impact.

This loss of about 1% per year is normal. In the following post, I will look at some of the proposed mechanisms for the aging process and then turn to how to overcome them.

Aging Gracefully – Part 2 Slowing The Aging Process

Can we slow the aging process?  The answer is a definite yes and it all has to do with our lifestyles and behaviors.  Here is a quiz.  What percent of Americans can answer yes to all five of the following statements?

 

Here’s a clue.  We know that about 20% of Americans smoke so the highest answer you can give to this question is that 80% could answer yes to all five.  The actual answer may surprise you.  It did me.  Only 3% of Americans can answer yes to all five! 

Let’s return to bone mineral density.  The way to slow BMD decline is to exercise and to eat a nutritious diet.  (Vitamin D supplements may also be necessary for those in temperate climates who get little sunshine on their skin.) So instead of a 1% decline per year it can be more of a ½% decline per year.  On the other hand for couch potatoe that decline won’t be 1% but it may be more like 1½ to 2% per year.  The same goes for cognition.  There are certain adverse factors such as vascular conditions and the metabolic syndrome (a precursor to diabetes) and also the chemicals released through chronic stress that speed up cognitive decline.  But there are also protective factors which we can control ourselves.  These include being physically active, intellectually challenged, and socially engaged.  It may be a surprise that physical activity is important for cognition but it has been clearly demonstrated to be critical.  Intellectual challenge is different than reading a book, even a complex book.  That’s not a challenge.  But if you belong to a book club and have to actively defend your perspective and point of view that then becomes a challenge.  Socially engaged means being involved as a human being with other human beings.  This is something that is frequently lost during older years if isolation develops due to limited mobility, inability to drive, etc. 

So the essential steps of slowing the aging process are: Avoid tobacco and remember it’s never too late to quit.  Reduce chronic stress because the chemicals released from stress have a very adverse effect on many physiologic systems such as immune function.  Eat a nutritious diet.  Do cognitive exercises which challenge your intellect.  Remain socially well connected. Physical exercise should include aerobic activity of about thirty minutes five days per week (just simple walking is adequate); resistance or weight training 2-3 times per week and balance exercises 2-3 times per week. 

 

To summarize, there is a steady slow loss of physiologic function in most of our organs over time. It is possible to slow this 1% decline and with it the ultimate functional impairments. It is also possible to avoid or certainly delay age-prevalent diseases.  But in both cases it’s up to us.  It’s up to us to adjust our lifestyles and we preferably need to do so beginning at a young age. That said, it is never too late to begin a preventive program.  We can slow physical decline with exercise, diet and reducing stress.  We can avoid many diseases by not smoking. We can slow cognitive decline with physical activity, intellectual challenges and social engagement.  It’s worth it.

Next post – The importance of comprehensive primary care in managing the aging process.

Aging Gracefully – Part 1 The Normal Aging Process

It is possible to slow the aging process.  No there is no Fountain of Youth and no, there is no pill that’s been discovered.  It’s all about lifestyle and this means starting at an early age and sticking with it through the years. 

I was recently invited to give a talk to a group of about 100 individuals contemplating moving to a continuing care retirement community.  The topic - is it possible to slow the aging process?  I titled it “Aging Gracefully.”  Here are my thoughts divided into three major categories:  the normal aging process, slowing the aging process, and (in a post to follow) obtaining the very best comprehensive health care.  The talk was picked up by the Howard Times of the Baltimore Sun; the reporter’s article is available at this link:  http://bsun.md/1AtQW7E

 “Old parts wear out.”  That’s normal aging.  It’s universal, it’s progressive and, at least as we know it today, it is irreversible.  Most organ functions decline by about 1% per year.  Fortunately our organs have a huge redundancy and so we can afford the declines without illness.  But eventually if we live long enough and the process continues at the usual rate a point is reached at which functional impairment or actual disease presents. 

Let’s use bone mineral density and cognitive function as examples.  During our childhood and teenage years our bone mineral density increases and with it our bone strength.  It reaches a peak at about age 20 and plateaus and then by age 35 starts a slow but inexorable decline of about 1% per year.  Should we live long enough we will reach a point which we can call the “fracture threshold” meaning that if we fall it’s possible to break a leg or a bone in our back.  Of course that 1% decline per year is an average.  Some people decline faster and some people decline more slowly.  We’ll come back to that point.  The same goes for cognitive function.  We’re at a peak at about age 20 and then there is a long plateau with a slow decline such that by the time we’re in our 80’s or 90’s most people have some noticeable decline in cognition. 

There are certain impairments that come with aging such as reduced vision, reduced hearing and reduced mobility.  We might not consider these as true diseases.  However there is also an increased prevalence of chronic illnesses such as heart failure, cancer, chronic lung and kidney disease and diabetes.  They often manifest in older ages but they actually originated many years ago.  For example coronary artery plaque buildup begins in childhood but may not manifest itself as a heart attack until the late 60’s.  Similarly lung cancer is on average diagnosed at age 72 but the cause began way back as a teenager when the person first went back behind the garage for a smoke. (BTW, not all lung cancers are due to smoking but for those that are, it was a long slow process over time.) 

These chronic illnesses are largely due to our adverse behaviors, our lifestyles.  The four big behaviors that need to be addressed are nutrition, exercise, chronic stress and tobacco.  We could add other factors but especially inadequate dental hygiene and excessive alcohol. All too many of us have poor nutrition (e.g. packaged and processed foods, lack of fresh fruits and vegetables, etc.) and at the same time we eat too much of it.  Most Americans don’t get an adequate amount of exercise.  It seems that everyone has some level of chronic stress and 20% of Americans smoke. 

To summarize, there is a normal aging process wherein organs reduce their function by about 1% per year. This rate of decline is related, in part, to our lifestyles beginning when we are quite young. There are also age-prevalent chronic diseases that are also life style driven. Our personal agendas need to include attention to healthy living so that we can preserve wellness.

Next time – Slowing the Aging Process