CONARD
AVERAGE AGE SCORES
100 +-
1959
= EXPOSED
» = UNEXPOSED
- # MEAN BOTH GROUPS
DISCUSSION
The various changes generally associated
with physiological senescence are known to
show wide variability among individuals of the
same age, and this was borne out by these data.
However, some of the criteria seemed to be
40 -
2c
30
40
30
60
AGE -YRS
70
80
Figure 20.
bv eye line. It can be seen that thecriteria
generally show either increasing or decreasing
values with increasing age. Many of the
changes, such as graying of the hair, balding,
arteriosclerosis — peripheral and retinal, skin
looseness, and skin retraction, do not manifest
themselves appreciably until after ages 35 to
40 years in the Marshallese. There is a tendency in manyof the curves for criteria, such
as blood pressure, graying of the hair, and loss
of visual acuity and accommodationto level off,
plateau. or even showslightly reduced values
in the older age group. The number of people
in the older age group is too small to make this
observation certain. However, American statistics on blood pressure (systolic and diastolic)
do showa plateau effect beyond about 60 years
of age and even a slight tendency to lowering
of blood pressures beyond this age (8). By
65-70 vears of age, arcus senilis in all Marshallese showed a 4+ change and so, of course,
plateaucd at a maximum. Some curves showed
lower maximums than others. For example,
baldness in women showed only 35° maximum. and arteriosclerosis of the retina showed
only 45° maximum. Ie is likely that the dif-
ference in the maximums among the various
criteria presented was due largelyto differences
in the degree of changes associated with the
various criteria, but also probably due to the
arbitrary nature of the scoring. The sex differences in hand strength and baldness were expected.
In the neuromuscular function test
) slight muscle fatigue may have been a factor
in causing the females to score lower, necessitating separate treatment.
50:2 144
better indices of aging than others, based on the
degree of change andthe variability of the data
observed.* Some of the better criteria seemed
to be accommodation of the eyes, visual acuity,
skin retraction, arcus senilis, graying of the
hair, and hand strength. One would expect
that the measured criteria would be more reliable than the estimated ones in view of the
subjective element and less precise scoring of
the latter. This seemed generally to be the
case, although the estimated values for graying
of the hair and arcus senilis were surprisingly
well correlated with age. The amount of subcutaneous fat probably influenced the skin
looseness measurements, but since loss of sub-
cutancous fat is somewhat age dependent, it
probably influenced it in the right direction. In
the future it is hoped that by statistical treatment of the data a weighting factor may be
assigned to each criterion based on the degree
of age-associated change and the degree of variability of the data. Since it is not always possible to run the complete battery of tests on
each individual, use of such weighting factors
on those tests run would tend to minimize disparity that might be related to the omission of
tests that were not run.
The data presented must be considered as
preliminary in nature and represent only a
small fraction of the many varied changes that
have been incriminated in the aging process.
However, under the conditions of examinations
of the Marshallese the battery of tests employed
is necessarily limited. As more experience is
gained, some of the tests may be eliminated and
newones added. It is believed the tests of vigor
are extremely important in assessing aging and
it is hoped that more tests of this nature may
be added. At this time the data are presented
to introduce a type of approach which might
offer a feasible means of assaying biological
age. Studies of the possible effects of radiation
on the aging phenomenon in human beings
may be aided by this method. In thecase of
the exposed Marshallese, results of further aging surveys will be carefully evaluated, comparing results in the exposed population with those
* Statement is not based on statistical analysis.