The concentration of sugar in the blood is the same at eight or eighty. Though there is no appreciable change in these constants, the ability to maintain equilibrium depreciates with aging. There is great diminution in tolerance for extremes. Older individuals cannot tolerate extremes of temperature. They become ill when they are cold. An annual trip to Florida and the desire to seek warmth in winter is an admission of senility.
Similarly, the elderly do not tolerate hot weather. Each summer in the twenty-five years of practice, I have seen anywhere from one to ten persons over seventy years of age collapse during a spell of hot weather. They seem to go all to pieces. Last week I saw a gentleman of eightyfour who, after several hot days, suddenly became too weak one morning to raise his head from his pillow. He has no recollection of a period of twenty-four hours. His collapse occurred because he did not compensate for the changed external environment by necessary dietary adjustments. All he needed was some salt. Two liters of saline solution were given into his vein, and in a few hours he wanted to get up and go home. You see, as we grow older we live by habit. He had not changed his habits. The hot weather made him sweat (in Washington we not only perspire, we sweat). Sweat is salty, but he drank only pure water and did not adjust to that necessity for an increased salt intake. His collapse was due purely to salt deficiency. Habit was the major cause of his difficulty. A child, whose dietary habits are not fixed by time, will usually demand salty food in hot weather. The older person responds to habit rather than makes adjustment to the environment.
The older person is less tolerant to starvation and to overeating. The ability to maintain a normal blood sugar concentration is lessened. Thus, it is frequently desirable for the aged to eat small quantities often, rather than to attempt to eat large amounts at longer intervals.
In the aged where the reaction to any stress is lessened, symptoms are less conspicuous. The symptoms of illness are not due to injury; they are due to the reactions of the body to the injury and in later life these reactions are less violent. We may see a man of seventy walking around, admitting he does not feel very well, but not complaining very much, despite the fact he is suffering from an extensive lobar pneumonia. . . . The older person's symptoms are much less conspicuous. Perhaps it is a blessing that illness in later years is associated with less subjective distress, but it is also a curse, inasmuch as medical attention is postponed. Too often the institution of therapy is delayed until such time that only a miracle can be expected to accomplish a cure. Pain is our friend, more precious than that dearest chum who warns us about halitosis. There are fewer accidents where there are stoplights.
The rate of aging change is by no means fixed; it is extremely variable. . . .
The asymmetry of aging is extremely significant to you and to me as individuals, as well as to the physician. First of all, there is a variation in the rate of aging at different times in the life span. For example, at puberty and the climacteric there is an acceleration of change in the structures involved in reproduction, whereas other structures do not show such acceleration of change at that particular time. There is a great variation of physical versus mental, and especially emotional maturation. For example, I am sure all of you have had experiences with individuals with old hearts but young ideas. They are likely to get into trouble because of this asymmetry; they play tennis long after they should cease. Perhaps a greater problem than being old too young, is the problem of being too young when old. Biologic age is by no means synonymous with chronologic age. They are not at all the same. They may coincide, but such parallelism is largely coincidental.