What are Chances Some of Us will become Centenarians?

[Guest guest]

Hi folks:

I was just looking at the Life Tables for the US for 2002 - the

latest year available. And yes, believe it or not (!), there is some

quite interesting information to be found there. One of the joys of

life, for me, is to come across some apparently nebulous, and

sometimes voluminous, data and spend some time wringing some

interesting implications out of it.

How many centenarians are there in the population today? Not many.

How often have you or I come across one? Ever? I don't remember

ever meeting one. In fact currently, if they got their data right,

0.019% of the US population is over 100 years of age. Put another

way, for every one of them there are 5,309 of us. Makes it sound

like there is little prospect of any of us ever making it. Right?

But wait. I suggest things are a **WHOLE LOT** better than that

number makes it sound.

For a start the present US population is 3.7 times as large as it was

when the present centenarians were born. So certainly the contingent

in which they were born was small compared with the present US

population, but nowhere near as small in comparison with theirs. So

comparing survivors in a cohort born 100 years ago with today's

population is not entirely helpful. In addition, many of them who

might have become centenarians were killed in World War I, or died of

infectious diseases such as tuberculosis which, while they used to be

right at the top of the list of causes of death until antibiotics

were discovered, do not even figure in the top ten today. In

addition, many of the present centenarian cohort died of heart

disease fifty years ago, the death rates for which have been

declining for the past ~fifty years and likely will continue to do

so. So we have many advantages never enjoyed by today's centenarians.

This is where the 2002 Life Table comes in. Life Tables show the

number of people surviving, out of 100,000 born alive, at every age

from the age of one year up to 100. It shows that today, more than

2% remain alive at 100 years of age. So that is a big increase from

the 0.019% number we started with. But even the 2% number

understates things too. Perhaps dramatically so. We have the

advantage that we are still alive. The table arrives at the 2%

number after assuming a lot of us have died on the way to our present

age. So of people still alive today, varying with your actual age

today, the proportion surviving to 100 will be appreciably greater

than 2%. In addition, better still, that table uses only today's

mortality rates in its calculations. Presumably future mortality

rates will be better than those of today. So the percentage chance

we have is again increased.

Then we have the trump card on our side ........... CRON. So how

do we fit this into the calculation? To answer this consider the

following: Suppose in the calculations I have done above, excluding

the effects of CRON, what percentage survival have we gotten up to?

I do not know the answer and am not about the spend time trying to

work it out accurately either. But, for sake of example, let's say

4%. Then the question that needs to be answered is: " Do you think

that CRON places us in the healthiest 4% of the population? " . Bear

in mind that CRON is the ONLY scientifically validated method that

extends maximum lifespan. Note also that there are probably at most

5000 people actually doing CRON in a population of ~290 million.

That is 58,000 of them for each one of us!!! Are you beginning to

feel better yet? If 4% of each annual population cohort fifty years

from now is still gonna be alive at age 100, and if we represent a

mere 0.000017% of the population, might it not be more reasonable to

ask whether perhaps almost all of us will be members of that 4%? So

perhaps instead we should be asking how many of us WILL NOT STILL BE

AROUND AT AGE 100?

What is more the wonderful 2002 Life Tables give us a pretty good

good way to calculate how many of us are likely still to be here.

But first a small digression is necessary. From time to time a

variety on numbers get dropped in CRON circles, such as ......

Jeanne Calment lived to 122; Or ......... (Walford) that the

practical maximum human lifespan under regular conditions is

110 " with very few outliers " ; Or ......... the average lifespan is

77 years; Or ...... 45% expansion of maximum lifespan in CRON mice;

Or ..... humans could live to 160.

It may be important to not muddle apples with oranges here. When Dr.

Walford mentioned 160 years he did not mean everyone on CRON would

live to be 160. I think rather that that number reflected applying

the lifespan extension seen in mice to the 110 year 'practical

maximum under regular conditions' .......... 110 x 1.45 = 160. In

other words, the practical maximum may be shifted by CRON from 110 to

160, and just as very very few regular people survive beyond 110,

under CRON very very few would survive beyond 160. But similarly,

applying the same ratio (160÷110) to people who might today be

expected to live to age 100, then that same proportion might now,

with CRON, be expected to live to 145 (100 x 160 ÷110).

What is more the Life Table allows us to calculate the same numbers

at many different ages. So here are the numbers adapted from the

2002 life table, this time for white males only (since that is the

category I happen to fall into currently), by applying the same ratio:

Percent¹ . Age²

-------- . ----

96% ...... 58.2

92 ....... 72.7

86 ....... 87.3

72 ...... 101.8

45 ...... 116.4

14 ...... 130.9

1 ...... 145.5

In other words if the 160/110 ratio applies to humans then, taking

the (pessimistic ..... today's mortality rates) projections of the

life table, 96% of CRON humans will live to 58.2 years. And 72% of

the CRON population might expect to live to 101.8, etc..

So, will the lifespan extension seen in mice (and very recently

approximately confirmed in rhesus monkeys also) be broadly

translatable to humans? Of course we do not yet know. The data in

the above table assumes the answer is " yes " . Of course, that has yet

to be proved.

¹ Percentage of the CRON population expected to reach age indicated.

² Age to which the number in the left column applies.

Rodney.